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595 Cards in this Set
- Front
- Back
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What is acanthosis?
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Thickening of the prickle cell layer (stratum spinosum) of the epidermis
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What is parakeratosis?
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Retention of nuclei in the stratum corneum of the epidermis - may indicate premalignant lesion such as actinic keratosis
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Most common malignant tumour affecting the periocular skin
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BCC
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Two main variants of BCC
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Noduloulcerative
Sclerosing / morpheaform |
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What is the relative frequency of BCC in different regions of the periocular skin
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Most frequently in lower lid
Then medial canthus, then upper lid, then lateral canthus |
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Typical features of BCC on LM
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"blue" and "below"
Basophilic Peripheral palisading on nuclei Retraction artefact --> clefts |
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Features of actinic keratosis on LM
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Thickened epidermis replaced by atypical squamous cells
Parakeratosis Solar elastosis in underlying dermis - elastotic degeneration |
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Features of SCC of eyelid on LM
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Nests, cords, islands of "pink" (eosinophilic) malignant squamous cells
Tumour cells deep to epidermis |
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What is keratoacanthoma?
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A crater-shaped squamous cells lesion that classically arises in elderly patients and then undergoes spontaneous involution
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Why should keratoacanthoma be excised completely? (versus small incisional bx)
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Overall configuration important to allow differentiation from SCC
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Which glands can sebaceous carcinoma arise from?
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Meibomian glands
Glands of Zeis Rarely, the sebaceous glands in the caruncle |
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Two-thirds of sebaceous carcinomas arise in the...
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Upper eyelid (more MG tissue)
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Key features of sebaceous carcinoma
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Large lobules are often necrotic centrally - "comedocarcinoma" pattern
Can invade and replace eyelid skin and conj ep in "pagetoid" fashion |
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How does sebaceous carcinoma spread?
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Direct extension
Metastasis to regional lymph nodes --> lung, liver, brain and skull |
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Mortality of sebaceous carcinoma
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About 15%
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Poor prognostic factors in sebaceous carcinoma
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Upper eyelid
Diameter > 10 mm Origin from MGs Duration symptoms > 6 months Infiltrative growth pattern Poor sebaceous differentiation Extensive pagetoid invasion Invasion of lymphatics, vessels and orbit |
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Multiple sebaceous gland neoplasms, especially sebaceous adenomas, are associated with which visceral cancer syndrome?
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Muir-Torre (especially colon carcinoma)
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Most lacrimal sac tumours are...
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...papillomatous neoplasms arising from the epithelial lining of the sac
Include exophytic and inverted papillomas composed of squamous cells, transitional cells, or a mixture |
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Most common intraocular tumour of childhood
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Retinoblastoma
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Mean age at diagnosis of RB
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18 months
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Features of RB under LM
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Viable tumour appears blue - poorly differentiated neuroblastic cells
Necrotic tumour cells lose basophilic nuclear DNA and become pink Dystrophic calcification appears reddish purple on H&E Rosettes and fleurettes |
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Four routes of spread of RB
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1. Direct infiltration along ON, or through bones or foramina
2. By CSF to SAS of brain and SC 3. Distant blood-borne metastasis to lung, bones and brain 4. Lymphatic spread via conj |
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Key prognostic factors in RB
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Presence and extent of:
ON invasion Extraocular extension into orbit Uveal invasion Size does not appear to be important |
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Wright rosettes
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Indicate neuroblastic differentiation
Lack a central lumen Relatively nonspecific for RB: also occur in neuroblastoma and medulloblastoma |
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Flexner-Wintersteiner rosettes
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Represent early retinal differentiation
Characteristic feature of RB Central lumen (subretinal space) Cilia with CNS doublet pattern project into lumen |
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Fleurettes
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Represent photoreceptor differentiation
Typically found in areas of viable tumour More commonly found in irradiated tumours Prominent eosinophilic cellular processes |
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The three most common conditions confused with RB
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Toxocariasis
PHPV Coats' disease |
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Why is NF1 one of the most common hereditary diseases?
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The NF-1 gene is quite large and subject to mutation
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Name the primary phakomatoses
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NF
Tuberous sclerosis von Hippel-Lindau (all AD) Sturge-Weber (sporadic) |
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NF-1 gene is coded on what chromosome?
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Chromosome 17
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Number of cafe au lait spots and of what size, is one the diagnostic criteria for NF-1?
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More than six, larger than 1.5 cm in diameter
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Ocular findings in NF-1
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Plexiform neuromas of lid and orbit
S-shaped lid fissure Congential glaucoma Lisch nodules Hamartomatous infiltation of the uvea with tactile corpuscle-like ovoid bodies Retinal and optic nerve gliomas Dysplasia of the sphenoid (Orphan Annie sign) Pulsating exophthalmos Slightly increased risk for uveal melanoma |
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What are plexiform neuromas composed of?
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A plexus of markedly enlarged nerves, which are swollen by a disorderly proliferation of Schwann cells and endoneural fibroblasts in a mucinous matrix
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Classic manifestation of NF-2
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Bilateral schwannomas of the eighth cranial nerve
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Ocular findings in NF-2
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Presenile PSCC
ERM Combined hamartoma of RPE and retina Optic nerve sheath meningiomas |
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Classic triad of tuberous sclerosis
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Epilepsy
Mental retardation Adenoma sebaceum - facial angiofibromas |
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Ocular findings in tuberous sclerosis
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Astrocytic hamartomas and astrocytomas in the retina (50% of patients)
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What is the location of the von Hippel-Lindau tumour suppressor gene?
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Chromosome 3p25
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Characteristic ocular manifestation of von Hippel-Lindau
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Cherry-like retinal angiomas with large feeding and draining vessels
(Histologically identical to the haemangioblastomas that may occur in the cerebellum) |
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Another name for von Hippel-Lindau disease
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Angiomatosis retinae
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Another name for Sturge-Weber syndrome
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Encephalotrigeminal angiomatosis
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Clinical features of Sturge-Weber syndrome
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Facial port wine stain (naevus flammeus)
Ipsilateral haemangioma of the meninges and brain "Train track" intracranial calcification |
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Ocular findings in Sturge-Weber
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Ipsilateral glaucoma and diffuse cavernous haemangioma of the ipsilateral choroid
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Presence of numerous eosinophils in a tissue section is highly suggestive of...
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An allergic reaction, or
Parasitic infestation |
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What does the term 'hof' refer to?
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The lighter-staining crescent next to the nucleus of a plasma cell - the Golgi apparatus
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Mast cells are found in the conjunctival __________ in conjunction with _________ disorders such as ____________ and _____. They are also seen in _________
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Mast cells are found in the conjunctival SUBSTANTIA PROPRIA in conjunction with ALLERGIC disorders such as VERNAL CONJUNCTIVITIS and GPC. They are also seen in NEUROFIBROMAS
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Macrophages are also known as...
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histiocytes
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If epithelioid histiocytes are observed histopathologically in a chronic inflammatory infiltrate, the inflammation is termed...
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Granulomatous
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Inflammatory giant cells are a....
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multinucleated syncytium formed by the fusion of epithelioid histiocytes
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Name three types of inflammatory giant cells
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1. Langhan's - TB
2. Foreign body giant cell 3. Touton giant cell - with chronic lipogranulomatous inflammation |
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To classified as chronic granulomatous an inflammatory infiltrate must contain...
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epithelioid histiocytes, inflammatory giant cells, or both
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Three main patterns of granulomatous inflammation
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1. Diffuse - "salt and pepper": sympathetic, lepromatous leprosy
2. Discrete - aggregates: sarcoidosis, TB 3. Zonal - rheumatoid scleritis, phacoanaphylactic endophthalmitis |
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A "pyogenic granuloma" is...
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an inappropriate, exuberant proliferation of granulation tissue that typically arises after minor trauma
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Tissue destruction, a hallmark of suppurative inflammation, is caused by the release of...
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digestive enzymes by degenerating polys
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Multiple vitreous microabscesses are a characteristic finding in...
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fungal endophthalmitis
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The term CMV is derived from...
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the cellular enlargement that is a characteristic cytopathic effect of the virus
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Intranuclear inclusions found in cells infected with CMV are often called...
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"owl's eye" inclusions - typically large and surrounded by a clear halo
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The vitreous in CMV retinitis is often relatively _____ in contrast to the ______ vitritis seen in ocular toxoplasmosis
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The vitreous in CMV retinitis is often relatively CLEAR in contrast to the INTENSE vitritis seen in ocular toxoplasmosis
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Classic ARN syndrome occurs in patients who are...
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not immunosuppressed
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The multiplicative activity of toxoplasma gondii in parasitized retinal cells causes...
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coagulative necrosis of retinal tissue
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Toxoplasma retinochoroiditis is an example of...
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a zonal granulomatous inflammatory reaction
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Why is the macula primarily affected in ocular toxoplasmosis?
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It is profusely vascularised, and the parasite is disseminated haematogenously
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"Headlight in the fog" refers to...
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obscuration of the white retinal focus of infection in toxoplasmosis, by an intense vitritis
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Russell bodies and morula cells refer to variations in the appearance of...
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plasma cells
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The most common cause of chronic granulomatous uveitis
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Sarcoidosis
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Behcet's disease is a systemic immune complex disease that causes...
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occlusive vasculitis
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What are the characteristic manifestations and diagnostic criteria of Behcet's disease?
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Genital and oral aphthous ulcers
Recurrent nongranulomatous iridocyclitis wih hypopyon |
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The pathologic diagnosis 'phthsis bulbi' is reserved for eyes that are...
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markedly atrophic and disorganized and have thickened folded sclera
interior of such eyes is usually filled with scar tissue, and intraocular structures are unrecognizable may see osseous metaplasia of RPE with chronic retinal detachment |
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Four layers of the eyelid
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1. Skin - epidermis and dermis
2. Striated muscle 3. Tarsal plate - MGs 4. Conj mucosa |
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What structures are normally found in the superficial dermis and often referred to as adnexal glands?
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Pilosebaceous follicles
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Features of eyelid
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Epidermis
Melanocytes Dermis Muscle Tarsal plate Adnexal structures (Zeis, Moll, Wolfring, Krause) Tarsal conj |
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What is the histological appearance of necrotising fasciitis?
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Purulent exudate between necrotic tissue planes: clumps of bacteria (strep pyogenes and staph aureus)
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Macro examination of a wart
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Hyperkeratotic nodule with surrounding skin
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Histo examination of a wart
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Hyperkeratosis
Vacuolated infected cells with inclusion bodies |
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Molluscum contagiosum is caused by what virus?
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Pox
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Histo exam of molluscum nodule/s
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Well circumscribed
Umbilicated - central mass filled with necrotic cells Infected cells in squamous layer are hyperplastic |
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Important differential of chalazion
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Sebaceous gland carcinoma
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Micro features of chalazion
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Dilated MG ducts
Lipogranulatomatous reaction - prominent fat spaces and multinucleate giant cells Abundant lymphocytes and plasma cells |
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Sudoriferous cysts are derived from which glands?
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Sweat glands of Moll
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Characteristic histo feature of sudoriferous cysts
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Double layer of cells on inner surface - inner cells cuboidal, outer of myoepithelial origin
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What is the essential difference between epidermoid and dermoid cysts?
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Presence of pilosebaceous follicles in wall of a dermoid cyst
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Features of epidermoid (sebaceous/retention) cysts
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Lined by stratified squamous ep
Lumen contains keratin |
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Where and in whom do dermoid cysts most commonly occur?
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In the upper lids of children
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Pathogenesis of dermoid cysts
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Incarceration of ectoderm between frontal and maxillary processes, during development
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Histo features of dermoid cysts
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Lumen contains keratin and hair
Walls contain hair follicles and pilosebaceous follicles |
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Why must care be taken when excising a dermoid cyst?
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Rupture releases highly irritant lipid and keratin causing a chronic granulomatous reaction
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What proportion of patients with xanthelasmas have normal lipid levels?
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More than 50%
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Histo exam of xanthelasmas
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Large clusters of ovoid cells with eccentric nuclei in the dermis
"Foamy cytoplasm" is almost translucent with pale granular material which stains with Oil red O |
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Three main types of naevus, based on anatomical classification
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1. Junctional
2. Intradermal (arrested migration from neural crest) 3. Compound (two types co-exist) |
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Positive immunohistochemical reactions in all naevi
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Melan-A
HMB45 S100 |
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Histo of junctional naevus
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Melanocytic proliferation confined to lower layers of epidermis in clusters
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What is the location of melanin in an active junctional naevus?
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Melanocytes transfer melanin into the squamous cells these are carried to the surface
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What is the malignant potential of an intradermal naevus?
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Far less than for junctional naevi
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Characteristic histo of a compound naevus
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Melanocytes in clusters within epidermis and dermis
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What is the correct term for a "seborrhoeic keratosis"?
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Basal cell papilloma
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What is the key histological feature of basal cell papilloma?
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Lack of maturation from basal to squamous cell type
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What tumour has the appearance of cauliflower at low magnification?
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Basal cell papilloma
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Key histo features of a squamous cell papilloma
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Surface heavily keratinised (may be filiform)
Marked differentiation from basal to squamous Intercellular spaces are prominent and contain cytoplasmic bridges |
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Histo features of keratoacanthoma
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Well demarcated
Squamous type cells Flat base Hyperkeratosis in central part Normal epidermis at edge of tumour |
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How does solar keratosis appear clinically?
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Flat, scaly plaque of variable size (15-20mm) and irregular periphery
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Key to pathogenesis of solar keratosis
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UV light to epidermis damages the DNA control of cell proliferation
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Usual treatment of solar keratosis
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Cryotherapy
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Immunohistochemical markers for cells of epidermal origin
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CAM 5.2
AE1 AE3 |
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Why is sclerosing BCC difficult to treat?
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Imprecise boundaries - requires wide excision
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How do BCC's spread?
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BCCs do not metastasize but sclerosing BCCs are known to locally invade the medial part of the orbit
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Characteristic histo feature of sclerosing BCC subtype
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Presence of small tumour cell nests within dense fibrous tissue, which contains a mixed inflammatory cell infiltrate
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Histo features of rare adenoid variant BCC
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Cells arranged in cords and acini resembling glandular tissue, with matrix containing MPS
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Clinical appearance of SCC
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Heavily keratinised nodular tumour
May be ulcerated Margins less distinct than a nodular BCC |
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How and when do SCCs metastasize?
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1. Lymphoid to preauricular or submandibular LNs
2. Perineural invasion Late |
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Aetiological factors in SCC
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UV exposure
Ionising radiation Chronic irritation HPV |
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Possible modes of treatment for SCC
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Surgical excision (preferred)
Cryotherapy Irradiation |
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What causes ulceration in SCC and what does it lead to?
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Malignant cells are unable to maintain normal surface protection
Leads to secondary infection and leucocytic infiltration, with underlying lymphocytic infiltration Malignant cells may induce fibrosis (desmoplastic reaction) |
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Grading of SCC
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Stages I-IV according to level of dedifferentiation
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Clinical presentation of sebaceous gland carcinoma
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Yellow nodule
May or may not be ulcerated Plaque-like lesion Chronic blepharoconjunctivitis with loss of lashes Recurrent eyelid inflammation like a chalazion Metastasis to LN and viscera |
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Basic element of a sebaceous gland
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Lobule, outlined by a single cuboidal basal layer of cells, which mature into large cells with a lipid-laden foamy cytoplasm with a small nucleus
Cells in neck of follicle fragment to release lipid into ducts (holocrine secretion) |
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Histo of sebaceous gland carcinoma
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Well differentiated - morphology is lobular
Less well - basal cells predominate Completely dedifferentiated - lipid spaces are rare, seen only at high mag |
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Rare malignant tumours to consider in differential of rapidly growing tumours of the eyelid
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1. Metastasis
2. Cutaneous melanoma 3. Kaposi's sarcoma - malignant spindle cells surrounding vessels with thin walls 4. Merkel cell tumour 5. Lymphoma |
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Most commonly identified pathogen in canaliculitis
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Actinomyces israelii - "sulphur granules"
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How are "dacryoliths" formed?
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By inspissated mucous and clumps of bacteria, and occasionally a FB
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Tumours of lacrimal sac
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Carcinomas are extremely rare
Tumours may be papillary or solid SCCs are identical to those in lid TCCs have an epithelial component of columnar cells Lymphomas have also been described |
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Three layers of conj epithelium
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Basal
Wing Cuboidal - microvilli |
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How to tell altered conj epithelium from skin
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Conjunctival ep will not possess rete pegs or be associated with pilosebaceous follicles
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Components of the chronic mixed inflammatory cell infiltrate of conjunctival papillae
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Lymphocytes, plasma cells, macrophages, and eosinophils
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Which stain is used to enhance the appearance of eosinophils after a scrape for the diagnosis of papillary conjunctivitis?
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Giemsa - bilobed and contain bright red granules
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Microscopic appearance of conj follicles
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Stroma contains small discrete lymphoid follicles which possess a germinal centre surrounded by mature lymphocytes
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Two main pathologically important causes of "dry eye"
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1. Age-related lacrimal gland atrophy (chronic infection may cause fibrosis and atrophy)
2. Chronic autoimmune inflammation (Sjogrens syndrome) |
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MIcroscopic features of KCS
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Age-related atrophy: lobules decrease in size due to fibrous replacement and fatty infiltration
Sjogren's syndrome: fibrous tissue replacement and dense lymphocytic infiltration Fibrous metaplasia of conj ep Loss of goblet cells |
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OCP is characterised by
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Recurrent conjunctival surface bullae and blistering with eventual scarring
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What is the pathogenesis of OCP?
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OCP is a type II autoimmune disorder (humoral) characterised by complement binding IgG and IgA deposits within the epithelial BM
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What should be done with conj biopsy specimen for query OCP?
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It should be partitioned for IF and immunohistochemistry before fixation for routine histology
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Histopath in OCP
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Non-specific
Bullae Dense mixed inflammatory cell infiltrate |
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OCP affects ________ whilst SJS affects _______
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OCP affects ELDERLY WOMEN whilst SJS affects YOUNG MEN
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Pathogenesis of SJS
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Drug-related (anticonvulsants)
Postinfectious (HSV or mycoplasma) HLA associations (B12) Immune complex vasculitis (Th) - type III immune reaction |
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Histopath in SJS
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Non-specific
Vasculitis Epithelial oedema Separation Oedematous stroma infiltrated by lymphocytes and plasma cells |
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Immunohistochemistry in SJS
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Immune complex deposition (IgA, IgG, and complement) in walls of blood vessels
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Main pathological feature of sarcoid granulomatous conjunctivitis
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Non-caseating giant cell granulomatous reactions in superficial stroma (central pale cells are epithelioid histiocytes)
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In conj infection by chlamydia trachomatis what do the organisms appear as on Giemsa stain?
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Early: elementary bodies
After proliferation and condensation: inclusion bodies |
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How is the diagnosis of trachoma made now?
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Using IF, but ELISA and PCR can also be used
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How does trachoma evolve pathologically?
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Through an early stage to a follicular and then papillary conjunctivitis, followed by stromal fibrosis and contractual scarring
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Histological features of pinguecula/pterygium
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Epithelium varies between atrophy, hyperplasia, metaplasia and dysplasia
Stroma contains hypocellular areas of degenerate hyalinised collagen, intermingled with areas of large clumps of red staining strands which stain positively for elastin (elastotic degeneration) Use Weigert's elastica and elastica van Gieson |
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Histology of pseudopterygium
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Consists of fibrovascular tissue which does not contain foci of elastotic degeneration
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Microscopy of conj epithelial inclusion cysts
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Lined by cells resembling conj ep on inner surface
Milky content due t secretion of mucin by goblet cells and desquamation of ep cells (which may undergo metaplasia to squamous type) |
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Features of a conj dermoid
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Commonly a solid white lump at limbus
May be fat and fibrous in the fornix (dermatolipoma) Histologically, contains adnexal structures within fibrofatty tissue |
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What is a conjunctival lymphatic cyst or lymphangiectasia?
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A hamartomatous malformation of lymphatics, characterised by large dilated lymphatics within the stroma of the conj
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How are conjunctival naevi classified?
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1. Junctional naevus - flat proliferation of melanocytes within the ep
2. Intrastromal naevus - nodular with small cysts 3. Compound - nodular and present in both ep and stroma |
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What proportion of conjunctival melanomas arise from pre-existing naevi?
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At least 20%
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With which special stain does melanin appear as black granules in a naevus?
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Masson-Fontana stain
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In what conditions may a conjunctival amyloid nodule appear?
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As part of a systemic amyloidosis or secondary to chronic inflammatory disorders such as trachoma and chronic keratitis
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What are the two types of conjunctival papillomas?
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1. Papillary/pedunculated
2. Placoid/sessile Both can have fibrovascular cores |
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How common is malignant transformation to an SCC in conjunctival papillomas?
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Rare, but has been reported
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What is the essential feature of CIN?
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The neoplastic cells have not penetrated the underlying BM
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Describe the usual clinical presentation of CIN
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Usually unilateral
In the interpalpebral fissure Close to limbus Usually flat with a gelatinous texture May have a pale white surface (leukoplakia) due to an oedematous keratin layer |
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Factors in pathogenesis of CIN
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More common in elderly
Long history of UV exposure HPV implicated Smoking Carcinogen exposure |
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Possible treatment of CIN
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Complete or partial excision biopsy for classification
Adjuvant cryotherapy Topical MMC controversial |
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What process represents the benign end of the CIN spectrum?
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Conjunctival dysplasia
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What process represents the more malignant variant of CIN?
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Carcinoma-in-situ (CIS): severe dysplasia
Stain positiviely for cytokeratin markers |
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What form does an excised conj SCC often take?
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Conj excision biopsy including a scleral flap
May be an enucleation specimen when tumour proliferation is extensive |
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What does the term PAM refer to?
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An expanding diffuse flat pigmentation in the conj, usually unilateral and occuring middle age or later life, at a site where pigmentation was not present
Describes a spectrum of: PAM without atypia, through mild, moderate and severe atypia |
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Microscopic features of BAM (benign acquired melanosis without atypia)
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Melanocytic proliferation is confined to basal layer
Melanasomes are transferred into normal superficial ep cells |
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Microscopic features of PAM with atypia
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Classification into mild, moderare or severe based on extent of infiltrating malignant melanocytes to superficial layers of ep
Mild - confined to basal and wing cell layers Moderate - basal and wing cells more affected Severe - full thickness infiltrated Like in CIN, the BM remains intact |
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What percentage of conj melanomas arise from pre-existing PAM?
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75%
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Where does metastatic conj melanoma spread to?
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Regional lymph nodes - examination is mandatory
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Microscopic features of conj melanoma
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May be spindle, epithelioid, or mixed
Mitotic figures Prominent lymphocytic infiltrate Tumour will react with melan-A, S-100, and HMB45 markers |
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What technique may be used to identify malignant melanocytes in the surface layer of the conjunctiva, in cases of suspected PAM with severe atypia?
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Impression cytology
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What is the prognostic significance of MALT tumours?
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These lymphoproliferative disorders occurring beneath mucosal surfaces have a better prognosis with treatment
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What is the spectrum of conjunctival lymphoproliferative tumours of MALT type?
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Benign reactionary lymphoid hyperplasia (BRLH) to frank malignant lymphoma
There is often a transformation from the more benign to the malignant variant during recurrences (multistep neoplasia) |
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What is the classic colour of conjunctival lymphoid proliferations and what are the common sites?
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Salmon pink
Bulbar conj and fornix |
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It is extremely important that any patient presenting with lymphoid neoplasia in the conj be what?
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Referred for general and oncological assessment for systemic involvement
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What is the treatment for primary conjunctival lymphomas?
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Excision biopsy followed by low dose radiotherapy (10 Gy)
Systemic disease treated as per oncologist |
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Describe the common macroscopic appearance of excision biopsy for conj lymphoma
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Smooth external surface
Homogeneous white cut surface Salmon-pink clinical appearance due to superficial vascularity |
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Histo and immunohistochem of BRLH of conj
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Follicular pattern resembling lymph node
Mixed cell population, including lymphocytes, plasma cells and histiocytes B and T cells (polyclonality) |
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Histo and immunohistochem of malignant lymphoma of conj
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Low power shows sheets of basophilic lymphocytes in stroma
High power cell maturation varies with primitive (coarse chromatin and multiple nucleoli) and mature lymphocytes Monoclonal, with B-cell type most common by far |
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What immunohistochemical label would demonstrate B-cell monoclonality in a malignant lymphoma of the conj?
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CD20 as a B-cell marker and peroxidase-antiperoxidase label
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With which stain does Descemet's membrane stain intensely pink?
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PAS
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What the various stains useful in the calcification of band keratopathy?
|
H&E: calcification appears as fine purple granules
von Kossa: combines silver salts with calcium phosphate Alizarin red: chelates calcium ions |
|
|
Histological features to look for when examining corneal epithelium
|
Hypertrophy v atrophy
Oedema / bullae Ulceration |
|
|
Histological features to look for when examining Bowman's layer
|
Absence v presence
Calcification Pannus Small breaks (KC) |
|
|
Histological features to look for when examining corneal stroma
|
Keratocytes
Scar Neovascularisation Stromal deposits |
|
|
Histological features to look for when examining Descemet's membrane
|
Thickening / guttata (Fuchs')
Multilayering (CHED or ICE) Breaks (trauma or KC with hydrops) |
|
|
Histological features to look for when examining corneal endothelium
|
Attenuation or absence
Presence of inflammatory cells |
|
|
What conditions disrupt the integrity of the corneal epithelium and expose the stroma, leading to bacterial infection?
|
BK
CT disorders that affect the periphery Trauma CL wear |
|
|
What are four types of tectonic surgery used in cases of impending corneal perforation
|
Lamellar graft
Conj flap Amniotic membrane graft PK |
|
|
Microscopic features of bacterial keratitis
|
Dense PMNL infiltrate
Infiltration of anterior uveal tissues by lymphocytes and plasma cells Loss of lamellar architecture due to collagenolysis Scar formation Descemetocoele Perforation |
|
|
What is the Brown and Brenn stain used for?
|
Favoured in the USA for visualising Gram negative organisms and Nocardia species
|
|
|
What can happen to the appearance of Gram positive bacteria on Gram stain, following antibiotic treatment?
|
They can become Gram negative in appearance
|
|
|
What is the most common organism causing bacterial crystalline keratopathy?
|
Strep viridans
|
|
|
Two microscopic features of bacterial crystalline keratopathy
|
Clumps of bacteria within the stroma easily seen on Gram stain
Minimal evidence of vascularisation and inflammatory cell infiltration |
|
|
Basic morphological subdivision of fungi
|
1. Yeasts: unicellular, budding, form hyphae in tissues
2. Filamentous: multicellular, branching hyphae - septate (Aspergillus) and non-septate (Mucor) 3. Dimorphic fungi: unicellular, yeast phase in tissues and mycelial phase in culture (Histoplasma) |
|
|
Special stains used for identifying fungi
|
1. PAS: stains cell walls, septae (red), and nuclei (blue)
2. Methanamine-silver (Grocott-Gomori): stains cell walls black 3. Gram: stains positive (blue) 4. Giemsa: stains organisms (blue) |
|
|
In what two forms does the acanthamoeba protozoan exist?
|
Motile trophoziote
Dormant cyst (resistant to chemical treatment) |
|
|
Diagnosis of acanthamoeba keratitis
|
Corneal scrape: inoculate confluent layer of E.coli laden non-nutrient agar
Wet specimen: examine by phase contrast microscopy for cysts and trophs In vivo: confocal microscopy |
|
|
Possible treatments for acanthamoeba keratitis
|
PHMB
Propamidine (Brolene) Neosporin Ketaconazole PK |
|
|
Histo features of acanthamoeba keratitis
|
Epithelium may be absent
Keratocyte content of stroma may be reduced (relative acellularity) Cysts and trophs Anti-acanthamoeba antibody (PAP stain) Calcofluor with fluorescent microscopy |
|
|
Seconadary lipid keratopathy may be seen in what conditions?
|
HSV
HZO Severe trauma Chemical injury Primary lipid keratopathy is extremely rare (Schnyder's crystalline keratopathy) |
|
|
Special investigations/stains in HSV keratitis
|
1. Phloxine-tartrazine stains nuclear inclusions purple or red
2. Giemsa and Papanicolaou stains 3. PCR for viral DNA |
|
|
What are the two variants of corneal disorders associated with rheumatoid disease, seen in keratoplasty specimens?
|
1. Stromal lysis WITH inflammatory cell infiltration
2. Stromal lysis WITHOUT inflammatory cell infiltration |
|
|
Factors implicated in rheumatoid keratitis
|
1. Unstable epithelium due to decreased tear production
2. Occlusive microangiopathy in limbal vessels leads to tissue ischaemia 3. Production of MMPs and reduction of TIMPs by keratocytes leads to collagenolysis 4. Release of IFN-gamma by Th2 cells in limbus stimulates macrophage activity |
|
|
Genetic associations of rheumatoid keratitis
|
Females predominate
HLA-DR1 HLA-DR4 |
|
|
Modes of treatment in rheumatoid keratitis
|
1. Promote epithelial healing with lubricants, mucolytics, and reduction of tear drainage
2. Immunosuppressants 3. Amniotic membrane or conj grafts in impending perforation 4. Surgery: cyanoacrylate glue and keratoplasty for perforation |
|
|
With respect to inflammatory rheumatoid keratitis, why is the inflammation in PUK so much more intense than in paracentral ulcers?
|
Due to the adjacent vascular limbus which facilitates migration of inflammatory cells
|
|
|
In the non-inflammatory form of rheumatoid keratitis, what is the usual location? And what is the presumed mechanism?
|
Paracentral
A collagenolytic cascade initiated by intrinsic corneal cells |
|
|
What is one of the constituents of the tiny yellow spherical bodies scattered throughout the superifical stroma in spheroidal degeneration?
|
Keratin - with Masson the particles are red or yellow in colour
|
|
|
What is the microscopic appearance of corneal blood staining after prolonged hyphaema?
|
Red cell fragments are demonstrated as blue spots by Masson stain
Iron atoms are bound within the haem molecule so staining for iron is negative Macrophages are not recruited |
|
|
Give two examples of the extremely rare epithelial corneal dystrophies
|
1. Cogan's "map-dot-fingerprint" - cystic spaces appear
2. Meesmann's - excessive BM deposition |
|
|
Genetics of stromal dystrophies
|
TGFbeta1 (big-H3) gene on 5q31 encodes keratoepithelin, an adhesion protein strongly expressed by corneal epithelium
Reis-Buckler Granular Lattice Avellino Thiel-Behnke, all have point mutations on big-H3, and are AD |
|
|
Histo features of Reis-Buckler dystrophy
|
Non-specific
Subepithelial fibrous nodules Epithelial oedema Fragmented Bowman's layer Absence of inflammation and NV Will usually be a lamellar keratoplasty specimen |
|
|
Histo features of granular dystrophy
|
Deposits of keratohyaline distort adjacent lamellae within superficial and mid stroma
Intervening stroma unaffected Deposits look red on Masson |
|
|
Histo features of lattice dystrophy
|
Amyloid deposits - more in the anterior stroma
Stain with Congo red - colour changes with direction of polarised light Deposits also in Bowman's layer (recurrent erosions) |
|
|
Avellino dystrophy combines the appearances of what two dystrophies?
|
Granular and lattice
Both keratohyaline and amyloid are intermingled in the anterior stroma resulting in reduced epithelial adhesion |
|
|
Which layers of the cornea are affected in macular dystrophy?
|
All layers except the epithelium by PG deposition
|
|
|
What is the inheritance of macular dystrophy?
|
AR on 16q22
|
|
|
Histo appearance of macular dystrophy
|
Stains for PGs (Alcian blue) shows deposition in every keratocyte with coalescence to form large clumps
|
|
|
What condition is the most common indication for PK from a corneal dystrophy?
|
Fuchs' endothelial dystrophy
|
|
|
What is genetics of Fuchs' endothelial dystrophy?
|
Although some studies have suggested a genetic basis, the majority of patients do not have a confirmed family history
|
|
|
Microscopic appearance of Fuchs' endothelial dystrophy
|
Central excrescences and an apparent thickening of Descemet's membrane
PAS required to show excrescences Attenuation of the endothelium |
|
|
What is the commonest protozoal parasite to infect the eye?
|
Toxoplasma gondii
It is neurotrophic - infection limited to retina and brain |
|
|
What are the two clinical presentations of toxoplasma?
|
Congenital
Reactivation / acquired |
|
|
Life cycle of toxoplasma
|
Oocysts in cat faeces
Ingestion of oocysts in soil or meat Trophozoites (free form) Bradyzoites (encysted form) Parasitisation within neural cells protects from immune system |
|
|
Five indications for treatment of toxoplasma
|
1. Sight threatening: involving macula, papillomacular bundle, and OD
2. Vasculitis: overlying a major retinal vessel 3. Persistence: more than a month 4. Severity: severe vitritis leading to significant visual loss 5. Immunosuppression |
|
|
Treatment options for toxoplasma
|
1. Folic acid antagonists - sulfadiazine and pyrimethamine (supplement with folinic acid)
2. Clindamycin, azithromycin, and atavaquone: cysticidal properties 3. Corticosteroids: introduce late 4. Others: argon laser ablation, cryo, vitrectomy |
|
|
What are the two separate pathological terms used to describe a shrunken globe?
|
1. Atrophia bulbi: preservation of choroidal and retinal anatomy
2. Phthisis bulbi: severe internal disorganization |
|
|
In the phthisical eye, reactive proliferation of what three cell types predominates?
|
1. Fibroblasts: form contractile broad sheets
2. Retinal glial cells: activated Muller cells and perivascular astrocytes 3. Epithelium: derived from ciliary body and RPE, capable of fibrous metaplasia |
|
|
What treatment is required prior to histological processing of a specimen of a shrunken globe containing ossification or calcification?
|
Decalcifying treatment with a weak acid
|
|
|
Microscopic features in a phthisical globe
|
1. Cyclitic membrane
2. Fibrous metaplasia and ossification of the lens 3. Retinal gliosis 4. Fibrous metaplasia of RPE to form bone 5. Relatively unaffected choroid 6. Atrophy of the optic nerve |
|
|
Clinical definition of a choroidal naevus
|
Flat circular, brown or slate grey with a size of less than 5 mm diameter and a thickness of less than 1 mm
|
|
|
What proportion of Caucasian eyes contain choroidal naevi?
|
20%
|
|
|
With what frequency does a choroidal naevus progress to malignancy?
|
1 in 10,000 - 15,000
|
|
|
Microscopic features of a choroidal naevus
|
Uniform heavily pigmented spindle cells in the stroma with sparing of the choriocapillaris
Nuclei uniform and mitotic figures absent Hard drusen |
|
|
What is the most common unilateral intraocular tumour in adults?
|
Ocular melanoma
Most frequent in Caucasians (7 per 1,000,000) |
|
|
What are the various clinical presentations of ocular melanoma?
|
1. Incidental finding
2. Visual disturbance if affecting macula 3. Peripheral field loss (may be exacerbated by exudative ret det) 4. Secondary glaucoma may follow angle NV 5. Proptosis, if there is extraocular extension 6. Hepatomegaly, if extraocular metastases |
|
|
Modes of treatment for ocular melanoma
|
1. Radiotherapy: brachytherapy (125-iodine or 60-cobalt); teletherapy
2. Laser: photocoagulation and transpupillary thermal therapy (TTT) 3. Surgery 4. Chemotherapy and palliation |
|
|
Prognostics from cytogenetic studies of ocular melanoma
|
Monosomy of chromosome 3, when combined with multiplication of 8q, carries a worse prognosis
Aberrations of chromosome 6 may be associated with a better prognosis |
|
|
Significance of vascular patterns in melanomas as assessed by PAS staining
|
Subdivided into:
Those that resemble naevi Those more typical of malignant melanoma: carry a worse prognosis when there is a network pattern or closed loop pattern involving three loops VEGF levels not an indicator of metastatic potential |
|
|
Prognostic indicators in malignant melanoma of the uvea
|
1. Cell type: spindle A best, spindle B worse, mixed worse, epithelioid worst
2. Size of tumour: larger are worse 3. Location: CB location worse than choroid 4. Invasion: extrascleral or vortex vein involvement 5. Age: worse with increasing age 6. Cytology: nucleolar size variation, vascular loops, mitotic activity 7. Genetics |
|
|
What is ocular melanocytosis?
|
Also called melanosis oculi
Congenital disorder in which there is an abnormal migration of melanocytes which accumulate in the episclera, sclera, and uvea An ipsilateral intradermal naevus of the eyelid may be present (naevus of Ota) |
|
|
What cell proliferation indices have been found useful prognostic indicators in ocular melanoma?
|
1. AgNOR technique: no longer used
2. Measurement of nucleolar area, particularly when SD is considered in relation to mean value 3. DNA synthesis: S-phase measured by mAbs such as Ki-67/Mib-1 or PCNA; cell cycling marker PC-10 |
|
|
Significance of ploidy analysis in ocular melanoma
|
Flow cytometry for choroidal melanoma has shown:
- spindle A cells are diploid and - epithelioid cells are tetraploid and aneuploid or hypertetraploid Correlation of recurrence and metastasis with distribution of DNA in a tumour population using ploidy analysis on fixed tissue is CONTROVERSIAL |
|
|
Macroscopic features of ocular melanoma
|
Subgrouped into nodular and diffuse
Most are nodular, ovoid, lightly pigmented, 10-15mm diam, at least 2mm thick Partially pigmented mushroom or collarstud shape Involvement of vortex vein carries poor prognosis Increasing size tends to spontaneous necrosis and/or transcleral spread Penetration of retina with seeding into vitreous is rare Enculeated globes often have: exudative ret det, extraocular spread, pupil block/NV glaucoma, cataract |
|
|
What causes the "classic" mushroom shape of a choroidal melanoma?
|
Constriction of the base by Bruch's membrane
|
|
|
Cell type classification of spindle cell melanomas
|
Spindle cell melanomas: A and B, mitotic figures are rare
A: closely packed, elongated oval nuclei, small nucleoli, longitudinal fold in nuclear membrane B: larger cells, rounder nucleus, with prominent nucleolus |
|
|
Microscopic features of epithelioid cell melanomas in comparison to spindle cell tumours
|
Larger than spindle cells
Cytoplasm more eosinophilic Poorer prognosis Cell boundaries are distinct and appear to be separated by intercellular spaces Nuclei do not overlap like spindle cells Mitotic figures more easily found Rarely, may dedifferentiate into an anaplastic variant with giant nuclei and multinucleate cells Purely epithelioid cell tumours rare (<5%) |
|
|
Microscopy of mixed cell melanomas
|
Contain both spindle cells and epithelioid cells
Represent the majority of choroidal melanomas |
|
|
General microscopic features of ocular melanoma cells
|
Mitotic rate is low but pyknotic cells showing apoptosis are often scattered throughout tumour
Focal necrosis is common |
|
|
Immunohistochemistry of ocular melanoma
|
Cells react positively with melan A irrespective of cell type
|
|
|
Differential diagnosis of pigmented choroidal lesion
|
Melanoma
Naevus Wet ARMD Choroidal haemorrhage Retinal macrocyst CHRPE Melanocytoma RPE adenoma/carcinoma |
|
|
Differential diagnosis of non-pigmented choroidal lesion
|
Amelanotic melanoma
Metastasis Choroidal haemangioma Choroidal osteoma Naevus Uveal effusion syndrome |
|
|
What is melanocytoma?
|
Also called magnocellular naevus
A rare benign form of melanocytic proliferation Presents like a malignant melanoma But heavily pigmented and often episcleral involvement Diangosis often made after surgical excision Appears as an intensely black mass in CB and episclera Histologically, tumour cells are large, heavily pigmented, and oval, with small, uniform nuclei Mitotic figures not seen |
|
|
What is melanocytoma of the optic nerve head?
|
A static hamartomatous proliferation of uniform round or oval heavily pigmented melanocytes that occur within the anterior part of ONH and in peripapillary retina
Usually asymptomatic and incidental finding Regular observation only, in case of misdiagnosis of melanoma |
|
|
Does early exenteration improve the overall survival in conjunctival melanoma?
|
No
|
|
|
What are the two forms of cavernous choroidal haemangioma?
|
1. Solitary: localised to the choroid
2. Multifocal diffuse angiomas: in the Sturge-Weber syndrome (also present in face, scalp, meninges and brain) |
|
|
How may a patient with cavernous choroidal haemangioma present?
|
May be asymptomatic
May have visual symptoms from SRF with progression to exudative ret det Sturge-Weber patient will have coexisting ipsilateral facial naevus flammeus and meningohaemangiomatosis |
|
|
Treatment options for cavernous choroidal haemangioma
|
1. Laser: photocoagulation or transpupillary thermotherapy
2. Radiotherapy: brachytherapy or external beam irradiation 3. Medical: glaucoma medications |
|
|
Macroscopic features of cavernous choroidal haemangioma
|
Elliptical dark red mass with interlacing fibrous septae in cut surface
May see subretinal exudation with ret det; cupping of OD and evidence of glaucoma surgery in S-W syndrome |
|
|
Microscopic features of cavernous choroidal haemangioma
|
Intraocular tumour with large vascular channels formed by fibrous septae lined by endothelium; fills choroid and extends to Bruch's
Circumscribed tumours end abruptly Diffuse multifocal tumours blend into peripheral tissue |
|
|
Types of CHRPE
|
1. Typical:
- Solitary, unifocal and unilateral - Grouped (or multifocal) and unilateral - "bear tracks" 2. Atypical: bilateral, with hypopigmented tail - Associated with FAP - FAP with osteomas and soft tissue tumours: Gardiner's syndrome (AD) - Associated with neuroepithelial CNS tumours: Turcot syndrome |
|
|
Histo features of CHRPE
|
Hypertrophy of RPE cells
In isolated form: cells are hyperplastic and multilayered, and melanosomes are much larger than normal Areas of lacunae and the halo indicate loss of RPE |
|
|
How common are adenomas and adenocarcinoma of the RPE?
|
Much rarer than those in CB
Can be misdiagnosed as choroidal melanomas Very few cases reported |
|
|
Choroidal osteoma is an excellent example of what?
|
A choristoma: a benign congenital tumour composed of cellular elements and tissues not normally at that site
|
|
|
What are the findings in choroidal osteoma?
|
Slowly progressive and painless visual disturbance, or asymptomatic
Benign static mass formed from compact and cancellous bone in posterior choroid Reliably diagnosed on ultrasound and CT Extremely rare; usually females |
|
|
What is the spectrum of retinal tumours in childhood?
|
RB is lethal if untreated
Hamartomatous astrocytic tumours, which may resemble small RB but remain static |
|
|
Initial and late clinical features of RB
|
Initial:
1. Abnormal looking eye: leucocoria and strabismus 2. Ophthalmoscopy shows tumour nodules (endophytic) or ret det (exophytic growth) Late: 1. Apparent uveitis: pseudohypopyon 2. Secondary NV glaucoma 3. Orbital involvement: proptosis |
|
|
Possible treatment of RB
|
Depends on size and extent of involvement of tumour, whether it's uni- or bilateral, and treatment centre
Enucleation Photocoagulation Cryotherapy Irradiation: external beam or brachytherapy Chemotherapy Cure rates with early dx and rx exceed 90% |
|
|
Macroscopic features of RB
|
White retrolental tumour
ON involvement may be evident when initial cuts are made across ON May see trans-scleral tumour May be endophytic or exophytic growth pattern |
|
|
RB has a preference to spread along what?
|
The ON
|
|
|
Immunohistochemistry of RB cells
|
Stain positively with:
Anti-S100 Anti-NSE Anti-GFAP Anti-S (photoreceptor soluble retinal antigen) in differentiated tumours |
|
|
Genetics of RB
|
Knudson two-hit hypothesis:
Deletion of both tumour supressor genes (RB1) on 13q14 chromosomes of a retinal cell 1. Hereditary form (40%) First hit is a germ line mutation Usually bilateral and earlier in life 2. Non-hereditary form (60%) Two hits to a somatic retinal cell Usually unilateral and present later |
|
|
What proportion of RB cases are unilateral and sporadic?
|
75%, of which 15% are the hereditary form
|
|
|
Statistical risk of inheritance of RB gene from a single sporadic unilateral case
|
Offspring 7.5% (uni) 50% (bi)
Sibling 1% (uni) 5% (bi) |
|
|
Differential diagnosis of RB
|
CARPET:
Coat's disease Astrocytic hamartoma ROP PHPV Endophthalmitis Toxocara retinitis |
|
|
What is Peters' anomaly?
|
A spectrum of anterior segment malformations
Characterised by a central corneal opacity (leucoma) at birth, due to a failure of formation of the posterior axial stroma and endothelium May occur in isolation, as part of wider ocular malformation, or as a systemic (Peters' plus) syndrome |
|
|
Clinical features of Peters' anomaly
|
Neonates presents with a central avascular corneal opacity - may be uni- or bilateral
May have irido-corneal adhesions and an anteriorly displaced cataractous lens 30-70% develop glaucoma despite treatment |
|
|
Subclassification of Peters' anomaly
|
Type 1: without lens involvement, but strands of iris may be attached at periphery of posterior corneal defect
Type 2: as with type 1 but with lenticulocorneal contact |
|
|
Genetics of Peters' anomaly
|
Not usually heritable
Some cases have PAX6 and CYP1B1 (glaucoma) mutations |
|
|
Possible modes of treatment for Peters' anomaly
|
Depends on severity:
PK if threatening amblyopia May need lensectomy Regular review for amblyopia, refractive error, and glaucoma Visual prognosis invariably poor despite treatment |
|
|
Pathogenesis of Peters' anomaly type 1
|
Failure of migration of the first wave of neural crest cells to form the endothelium and DM leads to posterior corneal stromal defect; associated failure in normal formation of iris in third wave of neural crest and mesenchymal migration leads adherent iris fragments
|
|
|
Pathogenesis of Peters' anomaly type 2
|
Incomplete separation of lens vesicle from overlying surface lens placode of developing cornea may interfere with first wave of neural crest cells, leading to defect in posterior stroma, DM, and endothelium
Lens may not move into optic cup, leading to apparent lenticulocorneal contact |
|
|
General meaning of term 'glioma'
|
Refers to a group of tumours derived from the supporting cells in neural tissue
Astrocytomas grades I-IV Oligodendroglioma GBM In ON: gliomas in children are equivalent to intracranial astrocytoma type I (low grade) |
|
|
Characteristic findings on hi-res orbital imaging of ON glioma
|
Fusiform enlargement on ON with axial proptosis
|
|
|
Treatment of ON glioma
|
Surgery
Unresponsive to radiotherapy and chemotherapy |
|
|
Microscopic features of ON glioma
|
Neoplastic astrocytes with oval or spindle-shaped nuclei and branching cytoplasmic processes
Destruction of myelinated axons within nerve bundles |
|
|
What is an ON meningioma?
|
A slowly growing neoplastic proliferation of meningothelial cells within the meninges of the optic nerve
Commonest in middle aged women A meningioma in the skull may spread into the orbit |
|
|
Management of orbital meningiomas
|
Usually conservative with serial imaging and VFs
Surgery still treatment of choice: ranges from local excision to exenteration combined with craniotomy for intracranial extension Tumour partially responsive to radiotherapy and hormonal therapy |
|
|
Histology of orbital meningioma
|
1. Meningothelial type is the commonest: fibrous septae surround small spindle cells which do not have a prominent cytoplasm - resemble cells in normal arachnoid mater
2. Psammomatous type contain numerous pink-staining "psammoma" bodies |
|
|
Who were von Hippel and Lindau?
|
Eugen von Hippel was a German ophthalmologist, who described the retinal angiomas in 1904
Arvid Lindau was a Swedish pathologist, who described the cerebellar and spinal angiomas in 1927 |
|
|
What is the normal axial length of the eye at birth?
|
16-19mm
|
|
|
Features of nanophthalmos
|
Microphthalmos alone
Eye has high lens/eye volume Generally hypermetropic, may have macular hypoplasia, uveal effusion, secondary retinal and choroidal detachments Susceptible to acute and chronic angle closure glaucoma |
|
|
Goldenhar-Gorlin syndrome
|
Bilateral condition characterised by epibulbar dermoids, accessory auricular appendages, aural fistulas, vertebral anomalies and hypoplasia of soft and bony tissues of the face
Sometimes associated with phocomelia and renal malformations Generally not inherited |
|
|
What stain is useful in xanthelasma?
|
Oil red O stain for fat
|
|
|
What is keratectasia?
|
A term that characterises a group of disorders in which there is stretching and thinning of the corneal stroma leading to an alteration in shape
May be primary (KC) or secondary (keratoglobus in congenital glaucoma) Differentiate from corneal staphyloma (lined by iris tissue) |
|
|
Clinical signs of keratoconus
|
1. "Oil droplet" and "scissoring" reflexes in ophthalmoscopy and retinoscopy
2. Fleischer ring 3. Vogt lines - vertical 4. Munson's sign |
|
|
Pathogenesis of keratoconus
|
Poorly understood
Genetic and environmental Collagenase/collagenase inhibitor imbalance hypothesis Link to chronic eye rubbing |
|
|
Genetics of keratoconus
|
Incidence increased in:
Trisomy 21 Vernal conjunctivitis and atopy Collagen disorders: Ehlers-Danlos syndrome, Marfan's, OI |
|
|
Macroscopic appearance in keratoconus
|
Corneal disc with axial/paraxial thinning of varying degrees
|
|
|
Microscopic features of keratoconus
|
1. Epithelial atrophy or hyperplasia
2. Breaks in Bowman's layer with subepithelial scarring 3. Hypercellularity of the stroma 4. Usually an intact DM 5. Irregular distribution of nuclei in the endothelium |
|
|
Special stains for keratoconus
|
Masson valuable for showing breaks in Bowman's layer
PAS useful for integrity of DM |
|
|
What are Fleischer rings in the keratoconic cornea?
|
Due to iron deposition at the base of the conus - presumably where tears pool and stagnate so iron salts are concentrated
Prussian blue stain |
|
|
What happens in corneal hydrops?
|
DM ruptures in region of conus allow an influx of aqueous into the stroma leading to corneal oedema
There is an elastic recoil Clefts form in stroma as aqueous seeps in |
|
|
How does a corneal dermoid look and how does it develop?
|
Presents as a large fibrovascular mass within the cornea at birth
Develops due to failure of surface ectoderm to differentiate to normal corneal epithelium - so ectoderm retains the properties of skin and forms pilosebaceous follicles and subepithelial fibrofatty dermal tissue |
|
|
Microscopic features of postaphakic corneal decompensation
|
Preserved Bowman's layer
Absence of stromal vascularisation Intact DM Epithelial oedema may be present Endothelial attenuation is pronounced May be evidence of concurrent infection or previous infection (replacement of Bowman's layer by scar tissue) |
|
|
What is a Khodadoust line?
|
A wave of advancing lymphocytes against a receding front of donor endothelium
|
|
|
Microscopic features of corneal graft rejection
|
Stroma and endothelium infiltrated by T lymphocytes and macrophages
|
|
|
Immunohistochemistry in corneal graft rejection
|
Markers for:
T-cells subsets (CD2-CD8) B cells (CD19,CD20,CD22) and macrophages (CD68) |
|
|
What is a retrocorneal membrane?
|
Imprecise apposition of donor and host corneal edges stimulates host keratocytes to proliferate behind the edge of the graft, forming an opaque crescent of tissue at the graft-host junction
Formation of a secondary DM may occur |
|
|
How does an amniotic membrane graft appear on histological examination?
|
Amorphous
Stains pink in H&E/PAS sections Epithelium may grow over or under the membrane |
|
|
How can a PRK/LASIK procedure be recognised in an intact cornea?
|
PRK: undulating grooves in stroma with compensatory epithelial hyperplasia
LASIK: an apparent interface shift in the stroma, with minimal scarring at the edge of the flap where the epithelial cover is intact May get epithelial ingrowth Specimen may be after lamellar graft |
|
|
Neither retinal arterioles nor venules contain what?
|
An internal elastic lamina
|
|
|
Systemic findings in von Hippel-Lindau syndrome
|
1. CNS haemangioblastomas
2. Cysts of kidneys, liver, pancreas, epididymis, and ovaries 3. Renal cell carcinoma 4. Phaeochromocytoma of adrenal gland |
|
|
Genetics of von Hippel's disease
|
Solitary uniocular tumours mostly sporadic
Bilateral multiples tumours likely associated with gene deletion on 3p25-26 (VHLS gene) with incomplete penetrance |
|
|
Possible modes of treatment for von Hippel's disease
|
1. Observe for "quiet" tumours
2. Photocoagulation, brachytherapy, proton beam teletherapy, or endocryotherapy for exudative tumours 3. Vitrectomy or conventional surgery for retinal detachments with a rhegmatogenous component |
|
|
Macroscopic and microscopic findings in von Hippel's disease
|
Macro: enucleated globe where haemangioma may be obscured by ret det
Micro: mass consisting of proliferating endothelial cells forming primitive capillary networks |
|
|
Description of Coats' disease
|
An idiopathic condition with the key feature being abnormal telangiectatic vessels with intra- and subretinal leakage of lipoproteinaceous fluid
Presents in 3-5 year olds as leucocoria with reduced vision and strabismus 80% cases are unilateral |
|
|
Pathogenesis of Coats' disease
|
Abnormal endothelium in sectors of retinal vasculature leads to a breakdown of BRB with resultant exudation
|
|
|
Possible modes of treatment in Coats' disease
|
1. Observation
2. Photocoagulation or cryotherapy for areas of retina with leakage on FFA 3. Vitrectomy and ret det surgery |
|
|
Macroscopic findings in Coats' disease
|
Enucleated globe with a thickened area within detached retina and a gelatinous subretinal exudate containing numerous cholesterol crystals
|
|
|
Microscopic features in Coats' disease
|
Abnormal vasculature identified on serial sections by spaces around the endothelium of affected vessels
Retinal oedema, disorganisation, and gliotic replacment Cholesterol crystals - birefringent in polarised light |
|
|
Who was Coats?
|
George Coats was a Scottish ophthalmologist
1908 |
|
|
What is ROP?
|
A vascular proliferative retinopathy of premature, low birth weight infants exposed to high and fluctuating levels of oxygen partial pressures.
|
|
|
Risk factors for ROP
|
1. Low birth weight (< 1000 g)
2. Short gestational age (< 29 weeks) 3. Multiple births 4. Race (2-fold increase in progression to severe disease in whites compared to blacks) |
|
|
Pathogenesis of ROP
|
Common theory (fluctuating oxygen)
Alternate theory (free radicals of oxygen stimulate mesenchymal spindle cells) |
|
|
Possible modes of treatment for ROP
|
1. Observation
2. Laser photocoagulation of peripheral non-vascularised retina 3. Vitrectomy and ret det surgery in selected cases |
|
|
Key difference between Coats' and ROP
|
In ROP integrity of endothelium in vasculature is preserved, so exudation is absent
|
|
|
5 clinical stages of ROP
|
I - white demarcation line
II - ridge or shunt between vascular and avascular retina III - Extraretinal fibrovascular proliferation IVa - traction subtotal ret det IVb - involvement of fovea V - total ret det seem as a retrolental white mass |
|
|
What is plus disease in ROP?
|
Vascular shunting of blood causes posterior venous engorgement and arterial tortuosity involving one or more quadrants
Clinically, see: Dilatation and tortuosity of peripheral retinal vessels Iris vascular engorgement Pupillary rigidity Vitreous haze Hallmark of rapidly progressive disease |
|
|
Location zones of ROP
|
Zone 1: OD to radius twice the distance from OD to fovea
Zone 2: radius of zone 1 to temporal equator Zone 3: temporal crescent of retina, not encompassed by other zones |
|
|
Pathological correlations of ROP stages
|
I - Proliferation of immature cells at periphery of avascular zone
II - Further hyperplasia of spindle cells, with proliferation of endothelial cells of the rearguard mesenchymal tissue III - Extraretinal neovascular proliferation IV - Fibrovascular bands and tractional detachment of retina V - Total ret det |
|
|
What is the most common mesenchymal soft tissue malignancy in childhood?
|
Rhabomyosarcoma
3% of all childhood malignancies 70% occur in first decade of life |
|
|
What is the male to female preponderance of rhabdomyosarcoma?
|
3 to 2
|
|
|
What is essential in the diagnosis of rhabdomyosarcoma?
|
Biopsy
|
|
|
What is the survival rate of rhabdomyosarcoma with current radiotherapy and adjuvant chemo?
|
Approaching 95%
|
|
|
What are the three categories of rhabdomyosarcoma?
|
From least to most differentiated:
Embryonal - only scanty evidence of cross-striations; strap cells Alveolar - malignant cells confined by circular fibrous septae - only 30% display cross-striations (Adult) pleomorphic - rhabdomyoblasts closely resemble striated muscle fibres |
|
|
Which antibodies are helpful in immunohistochemistry of rhabdomyosarcoma?
|
Myo-D
Actin Desmin |
|
|
What are the two types of Schwannoma?
|
Pallisading arrangement of nuclei (Antoni type A)
Loosely dispersed in a myxoid matrix (Antoni type B) |
|
|
The two commonest histological subtypes of intraorbital meningioma
|
Meningothelial type - fibrous septae surround small spindle cells which do not have prominent cytoplasm
Psammomatous type - contain numerous pink-staining "psammoma" bodies |
|
|
Types of lacrimal gland tumours
|
Epithelial (20-25%):
Pleomorphic adenoma (50% of ep) Adenoid cystic carcinoma Adenocarcinoma Lymphoid: BRLH ALH Malignant lymphoma Metastatic |
|
|
Features of pleomorphic adenoma
|
Benign "mixed" tumour
Well circumscribed on CT Peaks in fourth decade Male:female ratio 1.5:1 Pseudocapsule Complete excision by lateral orbitotomy to reduce risk of malignant transformation Micro shows epithelial and stromal components |
|
|
Features of adenoid cystic carcinoma
|
Most common malignant variant of lacrimal gland carcinoma
Peaks in fourth decade Capsule may not be intact "Swiss cheese" appearance Perineural invasion |
|
|
Infective causes of granulomatous reactions in the eye
|
TB
Leprosy Syphilis |
|
|
Non-infective causes of granulomatous reactions in the eye
|
SO
Sarcoidosis Lens-induced uveitis Scleritis VKH Behcet's |
|
|
Mechanism of acidic chemical injuries
|
Denaturation of proteins in epithelium leading to cell death
|
|
|
Mechanism of alkaline chemical injuries
|
Saponification of fatty acids within cell membranes by the hydroxyl ion, resulting in cell wall disruption
|
|
|
What forms may the injurious agent take in inflammation?
|
Physical
Chemical Infective Immunological |
|
|
What are the classical signs of acute inflammation?
|
Redness
Heat Swelling Pain Loss of function |
|
|
What are the components of the 'triple response'?
|
Flush - capillaries dilate
Flare - arterioles dilate Wheal - capillaries leak |
|
|
Factors increasing risk of endophthalmitis
|
Active host infection
Retention of infected foreign material Poor surgical technique Contaminated IOLs Debility, chronic corneal ulceration, and immunosuppression CL wear |
|
|
Classic tetrad of toxoplasma infection
|
Meningoencephalitis
Hydrocephalus Intracranial calcification Retinochoroiditis |
|
|
Four stages of trachoma
|
I - Early lymphoid hyperplasia and polys in conj stroma
II - Type A: lymphoid follicular reaction; type B: fibrosis with papillae; ingrowth of fibrovascular pannus on cornea III - Fibrous replacement of inflammatory tissue IV - Contraction within palpebral conj stroma; entropion, fibrosis of lacrimal gland; loss of goblet cells |
|
|
Infection cycle of toxocara
|
Adult worm lives in puppy GIT
Eggs passed in faeces Infant ingests eggs, which release second stage larvae in stomach Larvae pass through body but only induce inflammation when dead Can get: low-grade fibrous reaction at post. pole (?RB); exudation and ret det in mid-periphery; fibrosis at vit base |
|
|
Is silicone oil inert?
|
Not entirely
It stimulates a low-grade macrophagic reaction after oil becomes emulsified |
|
|
Sjogren syndrome is a disorder of the _______ glands of the conjunctival and oral mucosa, as well as the secretory _______ tissue of the lacrimal gland
|
Sjogren syndrome is a disorder of the ACINAR glands of the conjunctival and oral mucosa, as well as the secretory ACINAR tissue of the lacrimal gland
|
|
|
What is the unit Gray (Gy)? What approximate doses are required for for melanomas and RBs?
|
A measure of the amount of ionizing radiation energy absorbed in a target tissue
For melanomas, up to 110 Gy is required if 106RU plaque is applied For RB 40-60 Gy external radiation is required for RB |
|
|
Effects of irradiation on cells and tissues
|
Causes DNA damage
Short term: tissue destruction and suppression of cell division Long term: endarteritis (EC swelling, fibrin deposition, inflamm cell infiltration: narrowing of lumen); secondary dilation (telangiectasia) Loss of hair, teeth, and glandular tissue Massive necrosis of normal tissue when dose is excessive Increased risk of mutations - malformation of offspring, induction of second malignant tumour |
|
|
Damaged nerve cells are replaced by ______ cells, which are derived from perivascular _______ and _______ cells
|
Damaged nerve cells are replaced by GLIAL cells, which are derived from perivascular ASTROCYTES and MULLER cells
|
|
|
Scar tissue in the choroid is derived from what?
|
Scleral fibroblasts
|
|
|
What are the principal large vessel vasculitides?
|
Temporal arteritis and Takayasu arteritis
|
|
|
What the principal medium vessel vasculitides?
|
Classical PAN and Kawasaki disease
|
|
|
What are the major small vessel vasculitides?
|
Wegener granulomatosis
Churg-Strauss syndrome Microscopic polyarteritis Henoch-Schonlein purpura |
|
|
Why are the intraretinal arterioles not directly involved in temporal arteritis?
|
They do not possess an elastic layer
Elastic tissue is suspected as being the antigenic stimulus for the autoimmune reaction |
|
|
What is the classical histological triad of Wegener granulomatosis?
|
Small vessel vasculitis
Necrosis Granulomatous inflammation |
|
|
What is the difference between the generalised and limited forms of Wegener granulomatosis?
|
Generalised - present with renal, lung, URT and paranasal sinus involvement
c-ANCA + in over 90% Limited - URT and lung disease without kidney involvement c-ANCA + in only 60% |
|
|
What is the characteristic finding in SLE ocular disease?
|
'Lupus retinopathy' is characterised by retinal microinfarcts
Rarer, severe form has CRAO with haemorrhagic infarction |
|
|
What are 5 basic steps of cornel stromal healing?
|
1. Trauma with apoptosis of keratocytes at edges
2. Replacement by proliferation of adjacent keratocytes 3. Metaplasia to myofibroblasts with replacement of GAGs and collagen (III) 4. Production of HGF (promotes epithelial hyperplasia) and KGF and other CKs 5. Cross-linking of collagen |
|
|
6 characteristics of MMPs
|
1. Degradation of an ECM component
2. Each MMP has significant amino acid homology 3. Optimal activity at neutral pH 4. Zinc is a co-factor; calcium required for stability 5. Secreted in inactive state 6. TIMPs also exist |
|
|
Main MMPs
|
1. Collagenases
2. Gelatinases (A and B) 3. Stromelysin 4. Membrane-type MMPs |
|
|
How does corneal endothelium cope with gradual decline in population?
|
Very limited capacity to divide so adjacent ECs widen
|
|
|
What happens to keratocytes at wound interfaces in PRK and LASIK?
|
Apoptosis and resultant epithelial hyperplasia
May contribute to regression (more significant in PRK - closer to epithelium) |
|
|
Why does fibrosis not occur in the iris after a tear or a surgical wound?
|
The aqueous contains fibrinolysins
|
|
|
Secondary complications of perforating injury
|
1. Epithelial ingrowth
2. Fibrous ingrowth 3. Disorganisation of intraocular contents 4. Lens-induced uveitis 5. SO |
|
|
What reaction develops to a wooden IOFB?
|
A giant cell granulomatous reaction
|
|
|
List common inorganic IOFBs and reactions
|
1. Glass - minimal
2. Plastic - minimal 3. Iron - siderosis bulbi 4. Copper - acute chalcosis 5. Lead - diffusion of lead salts minimal; massive intracular fibrosis is a non-specific response to a perforating injury |
|
|
Theories proposed for aetiology of CMO
|
1. VMT
2. Diffusion of PGs from anterior segment 3. Damage to BRB |
|
|
Secondary effects of alkali burns
|
1. Destruction of conj cells leads to symblepharon
2. Loss of corneal stem cells 3. Stromal melting and thinning from liberation of MMPs 4. Fibrosis in anterior segment tissues leads to glaucoma and cataract |
|
|
3 principal effects of lasers
|
1. Photocoagulation - heat destruction (Argon 514nm)
2. Photodisruption - mechanical disruption (YAG 1064nm) 3. Photoablation - disrupts molecular bonds / vapourises (excimer 193nm) |
|
|
4 different types of ionising radiation
|
1. Beta irradiation - low penetration, used for surface tumours
2. Proton beams - focused on intraocular tumours like teletherapy for uveal melanomas 3. X-rays - higher penetration, used for RB, lymphoma, mets 4. Gamma irradiation - plaque brachytherapy (Ru109) for melanomas; collimated gamma knife external teletherapy for melanomas |
|
|
Long term sequelae of therapeutic radiotherapy
|
1. Eyelid and conj - telangiectasia, conjunctivitis, endarteritis obliterans
2. Lacrimal gland - KCS with ultimate corneal ulceration and perforation (40Gy) 3. Lens - PSCC (5Gy) 4. Retinal vasculature - breakdown of BRB with leakage of lipid-rich proteinaceous exduates, ischaemia, NVG (50Gy) 4. Optic neuropathy - due to endarteritis (60Gy) |
|
|
Macroscopic and microscopic findings in NAI
|
Macro - may see subdural and subarachnoid Hb in optic nerves; bleeding in retina and vitreous
Micro - may see Hb in vitreous or throughout retina (mostly NFL and nuclear layers): Prussian blue stain demonstrates iron in areas of prev Hb |
|
|
Popular theory for mechanism of Terson's syndrome
|
Excess CSF pressure within SAS around ON compresses retrobulbar portion and indirectly the retinochoroidal anastomoses and CRV --> impeded venous drainage leads to stasis and Hb
|
|
|
Common microscopic findings in a phthisical globe
|
1. Cyclitic membrane - metaplasia of ciliary epithelium
2. Lens - fibrous metaplasia, rarely ossification 3. Retinal gliosis - loss of neurons and glial cell proliferation 4. RPE - fibrous metaplasia, calcification, ossification 5. Choroid - relatively unaffected 6. Optic nerve - atrophy corresponds to extent of retinal degeneration |
|
|
What is the incidence of malignant transformation of an iris naevus?
|
1 in 4000-5000
Increased in Down's and NF1 |
|
|
Modes of treatment for iris naevus
|
1. Observation for growth/change
2. Excision by broad iridectomy if increases in size or alters pigmentation |
|
|
Features of iris naevus syndrome
|
Pigmentation of entire iris stroma (causing heterochromia)
Secondary glaucoma due to degeneration of trabecular ECs when overloaded with melanin |
|
|
Microscopic features of iris naevus
|
Heavily pigmented spindle-shaped melanocytes
Uniform nuclei with even chromatin and inconspicuous nucleoli Major part in anterior stroma |
|
|
Clinical presentation of iris melanoma
|
Iris mass that changes in size or appearance
Colour may be variable May be nodular or spread diffusely on iris surface Circumferential growth around angle may cause secondary glaucoma by infiltrating TM |
|
|
Modes of treatment of iris melanoma
|
Depends on clinical behaviour of tumour:
Observation Local excision Brachytherapy Enucleation |
|
|
What is the metastatic rate of iris melanoma?
|
Less than 2%
|
|
|
Macroscopic features of iris melanoma
|
Nodular form: submitted as iridectomy specimen
Diffuse form: enucleation is performed |
|
|
Microscopic features of iris melanoma
|
Cells are small and spindle-shaped
Uniform nuclei without conspicuous nucleoli Pigmentation is variable Mitotic figures extremely rare Invasion of outflow system establishes malignant nature of tumour Erosion of iris pigment epithelium common In recurrence, cells may transform into large, oval, "epithelioid cells" and tumour giant cells |
|
|
Two basic types of iris cysts
|
Lined by:
1. Corneal or conj epithelium - implantation after surgical or non-surgical trauma; usually anterior 2. Iris pigment epithelium: separation of two embryonic layers; posterior surface; congenital or acquired (miotics) |
|
|
Clinical presentation of iris cyst
|
Unilateral, pigmented, spherical, ovoid mass
May transilluminate May cause secondary angle closure Spontaneous rupture may cause acute uveitis and glaucoma |
|
|
Commonest source of metastasis to iris
|
Lung or breast
Also could be from lymphoma, leukaemia or metastatic carcinoid |
|
|
Spindle cell tumours of iris which are not melanocytic in origin
|
Leiomyoma
Schwannoma Vascular tumours Extremely rare |
|
|
Relative incidence of uveal melanoma in iris, CB, and choroid
|
Iris 8%
CB 12% Choroid 80% In proportion to numbers of melanocytes in each structure |
|
|
What are the tumours which may arise from the epithelium of the ciliary processes and pars plana?
|
Adenoma (commonest) and adenocarcinoma of NPE and PE
Commonly treated by local eye-wall resection Tumour forms solid nodular masses within and projecting from CB Some tumours consist of amelanotic cuboidal cells with uniform nuclei, others are heavily pigmented; often a combination |
|
|
What are the markers for cells of neural crest origin?
|
Melan-A
S100 HMB45 |
|
|
Clinical definition of choroidal naevus
|
Flat, circular, brown or slate grey
Size less than 5 mm diameter Thickness less than 1 mm |
|
|
What percentage of Caucasian eyes contain choroidal naevi?
|
20%
|
|
|
How often does a choroidal naevus progress to malignancy?
|
1 in 10,000-15,000
|
|
|
Macroscopic and microscopic features of a choroidal naevus
|
Macro: flat, brown mass in choroid; drusen may be present; rarely a shallow exudative detachment
Micro: small spindle-type cells, heavily pigmented; uniform nuclei and absent mitotic figures |
|
|
How is necrosis within a melanoma recognised?
|
Presence of pink amorphous areas, tissue fragmentation, and haemorrhage
|
|
|
Features of spindle A melanoma cells versus spindle B
|
Spindle A:
Closely packed with overlapping nuclei Longitudinal folds in nuclear membrane Spindle B: Larger cells than type A Rounder nuclei Prominent nucleoli |
|
|
Distinctive microscopic features of epithelioid melanoma cells
|
Tumour cells larger than spindle type cells
Cytoplasm more eosinophilic Cell boundaries distinct Cells appear to be separated by intercellular spaces Mitotic figures are more easily found |
|
|
5- and 25-year survival in malignant uveal melanoma
|
5 years - 50% alive
25 years - 20% alive |
|
|
What features might be seen in an enucleated globe following unsuccessful radiotherapy for uveal melanoma?
|
Range from:
No apparent effect to Complete necrosis and infarction May see: Tumour recurrence NVG Cataract Radiation retinopathy |
|
|
Features of melanosis oculi
|
Congenital disorder
Abnormal migration of melanocytes which accumulate in episclera, sclera and uvea Ipsilateral intradermal naevus may be present - naevus of Ota Increased risk of uveal naevus or melanoma, and glaucoma Histo shows dendritic melanocytes throughout uveal tract and scleral envelope Involvement of TM results in secondary glaucoma |
|
|
Features of melanocytoma of optic nerve head
|
Static hamartomatous proliferation of large uniform round or oval heavily pigmented melanocytes within anterior ONH and in peripapillary retina
Patient usually asymptomatic Regulation observation required to ensure diagnosis Enucleation not required Cells are oval and packed with melanosomes Nuclei are small, round and inconspicuous |
|
|
Features CHRPE
|
Circular flat black or brown areas in fundus
Asymptomatic Forms: 1. Typical - solitary or grouped (bear tracks) 2. Atypical - hypopigmented "tail"; associated with FAP; FAP plus osteomas and soft tissue tumours is Gardiner's syndrome (AD); also neuroepithelial tumours (Turcot syndrome) |
|
|
How common are adenomas/adenocarcinomas of the RPE?
|
Very few cases reported
|
|
|
In which tumours do the rare "fleurettes" more commonly occur?
|
Irradiated RB
|
|
|
Types of medulloepitheliomas
|
Non-teratoid:
Benign versus malignant (plenty of mitotic figures) 1. Acinar tissue (columnar cells of ciliary ep) 2. Primitive neuroblastic tissue (occasional rosette) Teratoid: Contains cells of each histogenic origin (ciliary ep, neural retina, and mesenchyme [cartilagenous]) |
|
|
Characteristic features of malignant lymphoid cells
|
1. Scanty cytoplasm
2. Multiple nucleoli 3. Crenated nuclear membranes 4. Clumps of condensed nuclear chromatin |
|
|
Features of primary lymphoid neoplasia
|
Retina thickened by tumour cell infiltration
Vascular occlusion Secondary haemorrhagic infarction Tumour cells often spread into vitreous Mitotic figures plentiful RPE infiltrated by malignant lymphocytes |
|
|
Features of secondary lymphoid neoplasia
|
Nodular infiltrates in any part of the uveal tract
Intensely basophilic ("if it's blue, it's bad") |
|
|
What is the usual cell type of infiltrating cells in primary and secondary forms of lymphoid neoplasia?
|
Large B-cell type
|
|
|
Give some examples of lymphocyte markers
|
CD5 - T-cell marker
CD20 and CD79 - pan B-cell markers |
|
|
What is the primary abnormality in Coats' disease?
|
Sectorial endothelial dysfunction - protein rich fluid leaks into the adjacent tissue
Inflammatory cell infiltration (macrophages and lymphocytes) is a secondary phenomenon |
|
|
In ROP, 'Plus disease' is the hallmark of rapidly progressive disease. What causes it and what are the 4 key clinical features?
|
Vascular shunting of blood causes venous engorgement and arterial tortuosity involving one or more quadrants
1. Dilatation and tortuosity of peripheral retinal vessels 2. Iris vascular engorgement 3. Pupillary rigidity 4. Vitreous haze |
|
|
Microscopic features of CRAO/BRAO
|
Initially inner layers of retina are oedematous
Later there is total atrophy of inner retinal layers as far as INL Occasionally may see atheromatous embolus (foamy macrophages lined by endothelium) or organising thrombus in CRA |
|
|
What conditions should be considered in the differential diagnosis of diabetic retinopathy?
|
CRVO
Radiation retinopathy HT |
|
|
Theorised mechanisms in diabetic retinopathy
|
1. Vasoproliferative factors
2. Aldose reductase (found in pericytes, converts sugars to alcohol) 3. Growth hormone 4. Platelets and blood viscosity 5. Apoptosis (fluctuations in BG cause pericyte death in vitro) 6. Autoimmune disease (Abs to pericytes) |
|
|
What degenerative changes in the precapillary arterioles contributes significantly to retinal ischaemia in DR?
|
Hyalinisation
Thrombus formation Embolisation Not all arterioles affected to same degree, leading to a patchy distribution |
|
|
What are the microscopic features of excised fibrovascular bands in DR?
|
Inner aspect lined by a hypercellular layer formed by proliferating ECs and capillaries
The retinal side then may show fibrous tissue containing feeder vessels |
|
|
What specific non-retinal features of diabetes can be identified by the pathologist?
|
Iris: vacuolated pigment epithelium, with cystic spaces containing PAS-positive glycoprotein
CB: thickened BM best seen with PAS stain |
|
|
5 stages of proliferative sickle cell retinopathy
|
1. Peripheral arteriolar occlusions with characteristic haemorrhages: black sunbursts or salmon patches
2. Arteriolar-venular anastomoses 3. Neovascular proliferation: "sea fan appearance" 4. Vitreous haemorrhage 5. Retinal detachment |
|
|
Clinical presentation of RP
|
1. Nyctalopia with prolonged dark adaptation
2. Loss of peripheral vision 3. Loss of central vision at final stage |
|
|
Classic fundus findings of RP
|
1. Bone spicules
2. Retinal arteriolar attenuation 3. Optic disc pallor 4. Atrophy of RPE and choriocapillaris 5. Vitreous cells in some cases Also may get: 1. Maculopathy: CMO, ERM, atrophy 2. PSCC |
|
|
Conditions with similar fundus appearance to classic RP
|
1. Usher's syndrome (AR, deafness)
2. Kearns-Sayre syndrome (mitochondrial myopathy) 3. Refsum's disease (skeletal abnormalities) 4. Hereditary abetalipoproteinaemia (malabsorption leads to A and E deficiency) 5. Bardet-Biedl syndrome (polydactyly, obesity, short stature) |
|
|
Pathogenesis of RP
|
Final pathway involves apoptosis of rods with cone degeneration at later stage
RPE responds by proliferation in retina (collect around atrophic blood vessels - bony spicules) |
|
|
Genetics of RP
|
AD commonest and best prognosis
(rhodopsin, peripherin) AR common and medium prognosis (cGMP gate channels, rhodopsin) XL rare and worst prognosis (Xp11 and Xp21; carriers may be patchy due to lyonisation) |
|
|
Microscopic features of RP
|
Photoreceptor atrophy is the initial event
Atrophic outer retina becomes gliotic Hyperpigmented RPE migrates into retina Macula often better preserved but has marked loss of nuclei in ONL |
|
|
Aetiology and pathogenesis of ARMD
|
Multiple aetiologies implicated including:
Choroidal arteriosclerosis Oxidative stress Diet Inflammation Genetics Cigarette smoking and HT both RFs for wet ARMD |
|
|
Nature and location of deposits between RPE and Bruch's in ARMD
|
1. Hard drusen: tiny, discrete, non-pigmented elevations between basement membrane and Bruch's
2. Soft drusen: indistinct borders, between basement membrane and Bruch's 3. Basal linear deposit: between cell membrane and basement membrane |
|
|
How are soft drusen and basal linear deposits thought to cause SRNVM?
|
Both stimulate cellular infiltration between Bruch's and the RPE - macrophages stimulate fibrovascular ingrowth, leading to plasma leakage, haemorrhage and further NV
|
|
|
With which stain is the basal linear deposit of ARMD best identified?
|
Picro-Mallory V stain
Deposit is blue, appears striated and is associated with overlying RPE and photoreceptor degeneration |
|
|
Difference between type 1 and type 2 SRNVM
|
Type 1 - Bruch's is penetrated by capillaries beneath the RPE
Type 2 - Bleeding and neovascularisation that occurs in the subretinal space (continuing leakage progresses to disciform scar) |
|
|
Differential diagnosis of SRNVM in ARMD
|
1. Trauma / iatrogenic (laser)
2. POHS 3. High myopia 4. Angioid streaks 5. Any condition that disrupts Bruch's |
|
|
What is a key distinguishing feature between the excised membranes of ERM and PVR?
|
ERM consists primarily of glial cells
In PVR the membrane contains pigmented cells derived from RPE |
|
|
What antibody label is used for immunohistochemical identification of glial cells?
|
GFAP - glial fibrillary acidic protein
Uses a brown chromogen |
|
|
What is the main histopathological feature of a myopic disc?
|
Gliotic retina on the temporal side overlying "bare" sclera
|
|
|
Microscopic features of lattice degeneration
|
Retinal thinning and hole formation in the region of a hyalinised retinal arteriole
Absence of vitreous over defect but attachments firm at edge |
|
|
Features of cobblestone/pavingstone degeneration
|
Atrophic gliotic retina fused with Bruch's
Choroid and choriocapillaris are atrophic RPE absent in scarred area but hyperplastic at periphery |
|
|
Features of peripheral microcystoid degeneration
|
Tiny cysts form in the OPL of the peripheral retina
As cysts enlarge, inner and outer retinal layers are bridged by surviving Muller cells, which may breakdown resulting in a retinoschisis |
|
|
What are the distinguishing features of retinal holes versus tears?
|
Both are full thickness defects of the retina
Holes are usually the result of peripheral atrophic changes and occur in the absence of vitreous traction; rarely cause detachment Tears result from persistent traction on focal adhesions between vitreous and retinal surface; progress if traction unrelieved |
|
|
How is artefactual detachment of the retina identified?
|
Attachment of photoreceptor fragments to the RPE
|
|
|
What structures does the orbit contain which may be involved in pathological processes?
|
Globe and ON
Muscles Lacrimal gland Nerves Blood vessels CT and fat |
|
|
What are the most common organisms identified by culture in orbital cellulitis?
|
Staph aureus
Strep sp. Haemophilus influenzae |
|
|
Which patients does Mucor classically affect?
|
Patients with DK
Immunocompromised |
|
|
What are the clinical characteristics of Mucor?
|
Rapid tissue destruction by:
Direct invasion Occlusive arteritis Leads to extensive necrosis of orbital contents, nasal passages, and sinuses May cause choroiditis |
|
|
Confirmatory investigation and treatment of Mucor
|
Biopsy and culture
IV amphotericin B Aggressive tissue clearance |
|
|
Histo features of biopsy in Mucor
|
Presence of non-septate branching hyphae - larger than other fungi
Extensive infarction of tissues due to thrombosis Stains like PAS and methenamine-silver may be useful |
|
|
What does orbital imaging commonly reveal in idiopathic orbital inflammatory disease?
|
CT/MRI reveal a mass with a ragged indistinct outline
|
|
|
Main histo features of idiopathic orbital inflammatory disease
|
1. Early stage: polymorphous infiltrate
2. Late stage: fibrosis |
|
|
How do amyloid deposits appear on microscopy?
|
H&E stain: pink acellular mass
Congo red stain: brick-red Polarised lights shows dichroism: parts appear red and green |
|
|
What are the characteristic histo features of an orbital biopsy in Wegener's granulomatosis?
|
Extensive necrosis in arterioles, venules, and adjacent tissue
Vasculitis with fibrinoid necrosis: best demonstrated with Martius-scarlet-blue (MSB) stain Dense inflammatory cell infiltration |
|
|
Histo features of GCA
|
Giant cell granulomatous reaction within media - multinucleate giant cells
Destruction of the internal elastic lamina Markedly thickened intima Organising thrombus in lumen |
|
|
Most common cause of unilateral and bilateral exophthalmos in adults
|
TED
|
|
|
When does the acute stage of TED occur following the diagnosis of systemic or localised thyroid disease?
|
2.5 years later on average
|
|
|
Stages of TED
|
Acute and chronic
Stage does not correlate with TFTs |
|
|
Werner's mnemonic for TED
|
NOSPECS
No signs of symptoms Only upper lid signs Soft tissue Proptosis EOM involvement Corneal involvement Sight loss due to ON compression |
|
|
Diagnosis of TED relies on what?
|
Accurate CT/MRI orbital imaging
Characteristic finding is enlargement recti with sparing of tendinous insertions Biopsy rarely indicated |
|
|
Important differential diagnoses of TED
|
Orbital lymphomas
Idiopathic orbital inflammatory disease |
|
|
Pathogenesis of TED
|
Humoral and cell-mediated mechanisms but aetiology not well understood
Accumulations of T and B cells within EOM leads to excessive MPS deposition, which attracts fluid with resultant swelling Chronic inflammation is followed by fibrosis |
|
|
Genetics of TED
|
Women 3-10 times more likely
Occurs later in men, but is more severe |
|
|
Possible treatment for TED
|
Topical lubricants
Systemic steroids Low dose radiotherapy Orbital decompression Eyelid surgery Strabismus surgery |
|
|
Microscopic features of TED
|
EOM fibres separated initially by MPS accumulation and infiltration by lymphocytes and plasma cells
Followed by fibrous tissue replacement Orbital fat looks normal MPS stain with Alcian blue Dense aggregates of lymphocytes (lymphorrhages) |
|
|
What is a mucocoele and what is it lined with?
|
An expansion of the paranasal space secondary to drainage obstruction from chronic sinusitis, trauma or a tumour
Most commonly affects frontal and sphenoidal Cystic cavity is lined with columnar epithelium occasionally containing goblet cells |
|
|
What is a haematic cyst?
|
Blood-filled cyst in orbit occurring spontaneously or following trauma
Fibrous wall contains breakdown products of blood with a giant cell granulomatous reaction to cholesterol Prussian blue stain shows iron deposits within macrophages as blue |
|
|
What is a teratoma?
|
A unilateral congenital tumour derived from pluripotential embryonic tissue of all germ cell layers
Present at birth May increase in size Histo may reveal dermal, neural, gastro, cartilaginous and osseous tissue |
|
|
Histo of cavernous haemangioma
|
Multiple blood filled spaces separated by thin fibrous septae lined with endothelium
Bleeding within mass creates large blood filled cysts May have a fibrous capsule |
|
|
What are histo characteristics of a neurofibroma?
|
Proliferating Schwann cells and fibroblasts around peripheral nerves
When formed within a number of closely associated nerves - plexiform neurofibroma |
|
|
Histo of Schwannoma
|
All cells are of Schwann cell origin
Characteristic mixed pattern with both pallisading arrangment of nuclei (Antoni type A) or loosely dispersed in a myxoid matrix (Antoni type B) |
|
|
Principal ocular feature of NF
|
Thickening of the uveal tract
Histo reveals Schwann cells and melanocytic proliferation - may mimic a diffuse melanoma Ovoid bodies formed by Schwann cell proliferation |
|
|
What orbital disease produces a mass that on imaging is classically described as "moulding" around the globe?
|
Lymphoproliferative disease
|
|
|
The primary unit within the lacrimal gland is the lobule. What structures does it contain?
|
Acini
Ductules Lymphatics Nerves |
|
|
What is Mikulicz's syndrome?
|
Bilateral swelling of both salivary and lacrimal glands secondary to sarcoidosis, lymphoid neoplasia, and leukaemia
|
|
|
What proportion of lacrimal gland tumours are epithelial in origin? And what proportion of those are pleomorphic adenomas?
|
20-25% are epithelial: pleomorphic adenoma, adenoid cystic, adenocarcinoma
Pleomorphic adenoma makes up 50% of epithelial tumours |
|
|
What biopsies and serological investigations are part of the work-up for Sjogren's syndrome?
|
Labial gland biopsy (more accessible)
ANA, RF, SS-A, SS-B |
|
|
What is the surgical treatment of lacrimal gland pleomorphic adenoma, and why?
|
Complete excision (including the pseudocapsule) by means of a lateral orbitotomy
If residual tumour is left behind there is a high risk of recurrence with the possibility of malignant transformation |
|
|
Lacrimal acini and ducts/ductules are lined by what cells?
|
Acini are lined by cuboidal cells
Ducts/ductules are line by cuboidal epithelial cells and a surrounding contractile cell layer (myoepithelial cells - mesenchymal) resembling a sweat gland |
|
|
What histo features might be seen in the lacrimal gland at a late stage of Sjogren's syndrome?
|
Extensive periacinar fibrosis
Marked reduction in number of acini Lymphocytic infiltrate within the fibrous tissue |
|
|
Microscopy of pleomorphic adenoma of the lacrimal gland
|
Two different components:
1. Epithelial: glandular pattern; lumen may be filled with eosinophilic proteinaceous secretion 2. Stromal: myoepithelial cells form CT; primarily fibrous with myxoid areas; tumour may also contain fat and cartilage Pseudocapsule is a fibrous condensation which contains infiltrating tumour |
|
|
Clinical features of malignant tumours of lacrimal gland which distinguish them from benign
|
Relatively faster onset of growth (<12 months)
Often painful proptosis Imaging shows destruction of adjacent bone with reactionary ossification |
|
|
Metastatic disease of the lacrimal gland usually presents with rapid proptosis. What may lead to enophthalmos?
|
Metastatic scirrhous carcinoma of the breast - due to orbital fibrous tissue contraction
|
|
|
Apart from breast, what other primary sources may metastasize to the lacrimal gland?
|
Lung
Prostate GIT Kidney |
|
|
What is the histo appearance of optic disc drusen?
|
An irregular basophilic mass within the nerve
|
|
|
What conditions are associated with optic disc drusen?
|
Predisposition to CRVO
Found in association with angioid streaks PXE |
|
|
What is the histo appearance of the ON in toxic/nutritional optic neuropathy?
|
Atrophy of the GCs in the papillomacular bundle (temporally located in retrolaminar part then centrally)
Loss of axons on Bodian stain and atrophy of myelinated axons on Loyez stain |
|
|
What is the theorised common pathway in toxic/nutritional optic neuropathy?
|
Disturbance of mitochondrial metabolism, which is thought to be more sensitive within the papillomacular bundle
|
|
|
Major clinical feature of Leber's hereditary optic neuropathy?
|
Apparent swelling of the NFL surrounding the disc, with radiating telangiectatic vessels
|
|
|
Micro features of gliomas
|
Gliomas consist of neoplastic astrocytes with oval or spindle shaped nuclei and branching cytoplasmic processes
Myelinated axons are replaced by proliferating astrocytes May see reactionary arachnoidal proliferation |
|
|
Histo of orbital meningioma of meningothelial type
|
Fibrous septae surround small spindle cells which do not have prominent cytoplasm - resemble those in normal arachnoid mater
|
|
|
Histo of psammomatous meningiomas
|
Contain numerous spherical pink-staining "psammoma" bodies - may be calcified
|
|
|
What are the 3 layers of the TM?
|
Uveal - fuses with ciliary muscle (oblique layers)
Corneoscleral - bridges sceral spur to cornea Juxtacanalicular (from inner to outer) |
|
|
Definition and incidence of congenital glaucoma
|
Glaucoma that arises before the age of 2
1 in 10,000 |
|
|
Triad of symptoms of congenital glaucoma
|
1. Photophobia
2. Epiphora 3. Blepharospasm |
|
|
Clinical signs of congenital glaucoma
|
Buphthalmos up to age 3 (scleral collagen more elastic)
Corneal oedema Haab's striae Amblyopia May see Barkan's membrane straddling the angle |
|
|
Pathogenesis and genetics of congenital glaucoma
|
Abnormal development of the TM
10% have strong hereditary component with variable penetrance - both AD and AR |
|
|
Macro and micro features of congenital glaucoma
|
1. Barkan's membrane
2. Hypercellularity of TM (failure of resorption of primitive embryonic tissue in angle) 3. Abnormal insertion of the ciliary muscle into TM (absence of intervening scleral spur) |
|
|
Risk factors for primary angle closure
|
1. Race (Eskimos and East Asians)
2. Gender (Women) 3. Age (Middle age) 4. Refractive error (hyperopes) 5. Family history 6. Predisposing anatomy (narrow angles or plateau) |
|
|
Macro and micro features of pseudoexfoliation syndrome
|
Exfoliation substance appears as fluffy white material on surface of zonular fibres
In H&E: irregular clumps have a pink amorphous appearance Stains weakly with PAS Iris pigmented epithelium has a "saw-tooth" pattern, and may be atrophic at pupil Substance may contain melanin pigment and be throughout TM, though concentrated in juxtacanlicular Schlemm's canal may be replaced by fibrovascular tissue |
|
|
What have immunohistochemistry and immunolabelling identified in PXF substance?
|
Mainly BM type consituents including:
Laminin Fibrillin Elastin Amyloid-P component Fibronectin Vitronectin |
|
|
Ultrastructural appearance of exfoliation substance
|
Fine fibrillogranular material
|
|
|
What are the 3 signs of pigment dispersion syndrome?
|
1. Krukenberg spindle
2. Iris transillumination defects (radially in midperiphery) 3. Darkly staining TM (from melanin deposition) |
|
|
Pathogenesis of pigment dispersion syndrome
|
The mechanical theory suggests posterior bowing (due to reverse pupil block) results in a zonule-iris rub
Melanin pigment granules are phagocytosed by trabecular endothelial cells - excessive accumulation may reduce outflow facility |
|
|
Microscopic features of phacolytic glaucoma
|
Macrophages containing lens matter (staining pink with PAS) can be found on aqueous tap
Macrophages accumulate on anterior surface of iris and inner layer of TM Macrophages label with CD68 |
|
|
In addition to posterior displacement of the iris root and collapse of the TM, after angle recession, what can contribute to traumatic outflow obstruction?
|
Migration of corneal endothelial cells across the inner surface of the TM and subsequent formation of a secondary DM
|
|
|
How does hyphaema cause raised IOP?
|
Exposure of TM to blood products in excess leads to obstruction to aqueous outflow
Acute effects are mechanical - occur because macrophages and lysed RBCs are unable to penetrate the intertrabecular spaces Trabecular ECs phagocytose red cell residues and resultant accumulation of iron from haem breakdown (siderosis) is toxic ECs degenerate and eventually fibrous replacement contributes to outflow obstruction |
|
|
By what 3 mechanisms can blunt and penetrating trauma produce injuries that lead to acute or chronic glaucoma?
|
1. Hyphaema/ghost cells
2. Angle recession 3. Epithelial downgrowth |
|
|
Why is enucleation the only option when glaucoma occurs secondary to an iris melanoma?
|
Filtering surgery enhances extraocular spread of the tumour
|
|
|
What changes may be seen on macroscopic examination of an enucleation specimen following neovascular glaucoma?
|
Bullous keratopathy
Peripheral corneal pannus Ectropion uveae Cataract Retinal changes relevant to vascular disease or tumour |
|
|
Microscopic features in neovascular glaucoma
|
Neovascular membrane - a layer of fibrovascular tissue on inner surface of TM, composed of small capillaries and spindle-shaped fibroblasts
Contraction of membrane results in closes angle Occasionally corneal endothelium may migrate across surface of neovascular membrane Also look for evidence of surgery or PRP |
|
|
What histological features may be seen in the TM of a failed case of ALT?
|
Loss of trabecular endothelial cells
Fusion of trabecular beams |
|
|
How does destruction of ciliary processes by transcleral laser or cryotherapy appear macroscopically?
|
CB depigmentation
|
|
|
What is the orientation of Haab's striae in congenital glaucoma?
|
Horizontal
|
|
|
In what condition might staphylomas occur in the region of the ciliary body?
|
Longstanding raised IOP
|
|
|
What are histological features of iris infarction due to acute glaucoma?
|
Stroma is acellular sectorally, with loss of dilator pupillae muscle (the hallmark) and atrophy of iris pigment epithelium
|
|
|
What are the striking histological abnormalities in the retina, after longstanding glaucoma?
|
Marked reduction in thickness of inner retina and preservation of outer retina
Absence of recognisable inner retinal layers with glial cell proliferation in the atrophic neural tissue |
|
|
What is the histological manifestation of optic disc swelling due to a rapid rise in IOP?
|
Swelling of the NFL from an interruption of anterograde axoplasmic flow in the prelaminar part of the ON
Bodian stain reveals distension of axons and swollen NFL displaces peripapillary photoreceptor layer |
|
|
How is the choroid affected in acute and chronic glaucoma?
|
Acute: congested
Chronic: atrophic |
|
|
What are histopathological features of optic disc cupping due to chronic glaucoma?
|
Early on there is dropout of axonal tissue and enlargement of the subarachnoid space
In later stages the NFL is extremely thin and optic cup becomes filled with disorganised gliotic tissue At end stage the prelaminar neural tissue is absent and lamina cribrosa is bowed |
|
|
Features of Tay-Sachs disease
|
GM2 gangliosidosis
Hexosaminidase A deficiency Gangliosides accumulate to toxic levels in CNS neurons Get cherry-red spot Autosomal recessive (HEXA gene) |
|
|
Who were Tay and Sachs?
|
Warren Tay was a British ophthalmologist who described the cherry-red spot in 1881
Bernard Sachs was a NY neurologist who noted increased prevalence in Ashkenazi Jews in 1887 |
|
|
What is a Bergmeister's papilla?
|
Posterior glial remant of the hyaloid system
|
|
|
What is the usual location of an optic disc pit?
|
Inferotemporal quadrant
|
|
|
In what layer of the retina do diabetic exudates characteristically occur?
|
OPL - eosinophilic material; may stain positive (red) with oil red-O stain
|
|
|
Common locations for dermoids
|
Upper eyelid
Peripheral cornea Superotemporal orbit |
|
|
Which form of acanthamoeba is double-walled?
|
Cysts
|
|
|
What sort of tumour contains Rosenthal fibres? What are they?
|
Optic nerve glioma - degenerative eosinophilic substances found within the cytoplasm of astrocytes
|
|
|
What may cause a sudden increase in proptosis in a patient with known optic nerve glioma?
|
Malignant transformation or coalescence of cystic spaces
|
|
|
What tumour has a 'railroad track' appearance on CT?
|
ON meningioma
|
|
|
Possible modes of treatment for conj PAM
|
1. Observation
2. Excision biopsy to identify the subtype of acquired melanosis or if malignancy is suspected 3. Cryotherapy to larger areas 4. Topical antimetabolites (MMC) are also used |
|
|
Describe the two histopathological subgroups of PAM
|
1. BAM - PAM without atypia: melanocytic proliferation confined to basal layer
2. PAM with atypia - mild, moderate or severe: based on appearance of melanocytes and extent of infiltration to superficial layers Mild: confined to basal and wing Mod: basal and wing affected more extensively Severe: full thickness infiltrated with marked variation in nuclear size and shape (BM intact) |
|
|
What stain and immunohistochemistry is useful in conj PAM?
|
Masson-Fontana to determine extent of melanin deposition
Melan-A, HMB45, and S-100 useful to confirm diagnosis in amelanotic cases |
|
|
To where do conj melanomas spread?
|
Regional lymph nodes
|
|
|
Examination of ________ ______ _____ for metastatic spread is mandatory in conj melanoma
|
Examination of REGIONAL LYMPH NODES for metastatic spread is mandatory in conj melanoma
|
|
|
In band keratopathy, at what level is the calcification?
|
Bowman's layer
|
|
|
How do the keratinoid deposits of spheroidal degeneration appear on microscopy?
|
Yellow/orange spherical bodies throughout superficial stroma using a Masson stain
|
|
|
How do amyloid deposits appear with polarised light? With Congo red staining?
|
Exhibit either red or green dichroism
Irregular red clumps with Congo red |
|
|
Why does corneal blood staining occur?
|
Prolonged hyphaema in the setting of high IOP makes fragments of Hb diffuse into the stroma - macrophages are not recruited to remove them
|
|
|
How do cholesterol crystals appear in routine paraffin sectioning?
|
As clefts
|
|
|
How do red cell fragments in the corneal stroma appear with Masson staining?
|
Blue spots
Iron atoms are bound within haem molecule and staining for iron is negative |
|
|
Corneal epithelial dystrophies are extremely rare. Give two examples.
|
Cogan's "map-dot-fingerprint" - cystic spaces appear
Meesman's - excessive BM deposition |
|
|
What stains are useful for stromal dystrophies of the cornea?
|
1. PAS: MPSs stain red/magenta on pink stromal background
2. Masson: keratohyaline look red on green stromal background 3. Congo red: amyloid looks orange/red (with red-green dichroism) on pink stromal background 4. Alcian blue: MPS look blue/green on pale green stromal background |
|
|
What does the Big-H3 gene encode and what does it do?
|
beta transforming growth factor-induced gene, also known as TGF-beta1 on chromosome 5q31
Encodes protein keratoepithelin which functions as an adhesion protein and is strongly expressed by the corneal epithelium |
|
|
Which stromal dystrophies are related to point mutations on the Big-H3 gene? How are they inherited?
|
Reis-Buckler
Granular Lattice Avellino Thiel-Behnke All AD The different phenotypes are due to different diffusion properties of mutated keratoepithelin proteins and their abilities to aggregate and form amyloid deposits |
|
|
Deposits in Bowman's layer in lattice dystrophy leads to what?
|
Recurrent epithelial erosions
|
|
|
What are the 2 subtypes of macular dystrophy?
|
Type 1 - sulphated KS absent in serum
Type 2 - sulphated KS present in serum |
|
|
What are the excrescences (guttata) on DM in Fuch's composed of?
|
Abnormal deposition of collagen and GAGs
|
|
|
What stain is always required to show excrescences in Fuch's ED?
|
PAS
|
|
|
Salient features of CHED
|
Bilateral diffuse corneal cloudiness in infancy
AD and AR variants on 20p11 Layer of fibrous tissue lines DM ECs attenuated |
|
|
Salient features of PPD
|
Bilateral circumscribed opacities in childhood
AD and AR variants on 20p11 Stratified squamous cells line posterior cornea (metaplastic ECs - desmosomes and microvilli) DM normal thickness |
|
|
Salient features of ICE
|
Unilateral
Iris naevus; Chandler's; essential iris atrophy ECs contain vesicles; DM normal thickness |
|
|
How is keratectasia differentiated from a corneal staphyloma?
|
In a corneal staphyloma the thinned deformed cornea is lined by iris tissue
|
|
|
In which syndromes is the incidence of keratoconus increased?
|
Trisomy 21
Vernal conjunctivitis and atopy Collagen disorders: Ehlers-Danlos, Marfan's, OI |
|
|
Useful stains in keratoconus
|
Masson for demonstrating breaks in Bowman's layer
PAS for examining integrity of DM |
|
|
Microscopic features of keratoconus
|
1. Epithelial atrophy or hyperplasia over apex
2. Breaks in Bowman's 3. Hypercellularity of the stroma 4. Usually intact DM 5. Attenuated endothelium with irregular nuclei |
|
|
What constellation of signs constitutes Goldenhar's syndrome?
|
Biateral limbal dermoids
Preauricular skin tags Lid colobomas Hemifacial microsomia |
|
|
What is ECD at birth? At what level does the cornea decompensate?
|
6000 cells/mm2
800 cells/mm2 |
|
|
How does amniotic membrane appear on H&E/PAS stains?
|
A layer of pink amorphous material
Epithelium may grow under or over membrane |
|
|
What are the changes seen in the cornea after PRK?
|
If concentric rings were produced there may be undulating grooves in the stroma with compensatory epithelial hyperplasia
|
|
|
What histological changes may be seen in a cornea following radial keratotomy?
|
A thin scar extending almost to DM
May see epithelial ingrowth through a defect in Bowman's layer |
|
|
How may a LASIK procedure be recognised histologically in an intact cornea?
|
By an apparent interface shift in the stroma, with minimal scarring at the edge of the flap where the epithelial cover is intact
|
|
|
At what level do flame, dot and blot haemorrhages occur?
|
Flame: NFL
Dot: OPL Blot: subretinal |
|
|
Who was Roth?
|
Maurtiz Roth was a Swedish pathologist who described Roth's spots in 1907 (in patients with SBE)
Circular areas of haemorrhage with a white centre Occlusion of feeder arteriole by septic emolus --> leakage of fibrin |
|
|
What is the natural history of hard exudates histologically?
|
Initially they appear as homogeneous pink-staining areas within OPL
At an early stage, macrophages (intrinsic glial cells) migrate into exudate At a later stage, macrophages become distended with lipoprotein and disruption of OPL leads to degeneration of PR cells |
|
|
What are Elschnig's spots?
|
Focal chorioretinal infarcts seen in advanced HT retinopathy
|
|
|
Who was Elschnig?
|
Anton Elschnig was an Austrian ophthalmologist who described the spots and pioneered corneal transplantation
|
|
|
What are the secondary effects of retinal arteriolar spasm as occurs in HT retinopathy?
|
Haemorrhage and microinfarction
|
|
|
Which vessels undergo fibrinoid necrosis in HT?
|
Renal and choroidal arterioles
NOT a feature of retinal arteriolar disease |
|
|
Microscopic findings in CRAO
|
Initially inner layers of retina are oedematous, followed by a total atrophy as far as INL
Occasionally, an atheromatous embolus or organising thrombus is seen in CRA |
|
|
How do PRP scars appear histologically?
|
Sectors of outer retinal destruction or total retinal destruction depending on energy level and wavelength applied
Muller cells are thought to be the source of the glial cells in the scars - these have large irregular nuclei |
|
|
What are the 5 stages of proliferative sickle cell retinopathy?
|
1. Peripheral arteriolar occlusions (characteristric haemorrhages: black sunbursts and salmon patches)
2. Arteriolar-venular anastomoses 3. Neovascular proliferation ("sea fan appearance") 4. Vitreous haemorrhage 5. Retinal detachment |
|
|
The term "retinitis pigmentosa" is a misnomer in that the disease is a retinal dystrophy without evidence of what?
|
Inflammation
|
|
|
3 common symptoms in RP
|
1. Nyctalopia
2. Loss of peripheral vision 3. Loss of central vision in final stage |
|
|
5 classic fundus findings in RP
|
1. Bone spicules
2. Retinal arteriolar attenuation 3. Optic disc pallor 4. Atrophy of RPE and choriocapillaris 5. Vitreous cells in some cases |
|
|
Associated ocular findings in RP
|
1. Maculopathy: CMO, ERM, and/or macular atrophy
2. PSCC |
|
|
Complications of disciform scar in ARMD
|
Continuous subretinal traction may lead to retinal distortion, rupture of vessels, and vitreous haemorrhage
Haemorrhage may be complicated by massive retinal detachment and subretinal mass may simulate a melanoma |
|
|
List some causes of ERM
|
1. Idiopathic
2. Uveitis 3. Previous trauma including surgery 4. Diabetes and other vascular diseases |
|
|
What does excised tissue from an ERM primarily consist of?
|
Glial cells
|
|
|
Clinical features of axial myopia
|
Elongation of globe with possible posterior staphyloma
Lacquer cracks Disc changes (tilting and PPA) due to posterior stretching of the sclera |
|
|
In which quadrant of the retina is lattice degeneration most common?
|
Upper temporal
|
|
|
In which area of the retina is cobblestone degeneration most common?
|
Inferior peripheral
|
|
|
Factors involved in pathogenesis of rhegmatogenous retinal detachment
|
1. Syneresis with liquefaction of vitreous gel
2. Persistent vitreous traction 3. Retinal break 4. Fluid movement from vitreous into subretinal space |
|
|
List one significant complication of an encircling band
|
Sclera can be eroded
|
|
|
How long after a detachment will the retina not recover?
|
longer than 6 weeks
|
|
|
What changes may be seen at the end stage of a chronic detached retina?
|
Becomes contracted
Then shows ischaemic atrophy, gliosis, and cyst formation Evidence of neovascular glaucoma may be present |
|
|
What is the principle of conventional surgery to repair retinal detachment?
|
To close the break by placing the RPE in direct contact with the sensory retina and
to relieve retinal traction |
|
|
What different materials have been used for explants in retinal detachment surgery?
How do they appear in histological specimens? |
Include sponge and solid silicone
Explants are removed prior to sectioning - the site appears as an oval space forming an identation in the sclera |
|
|
What changes are seen in the retina following laser photocoagulation retinopexy and PRP?
|
Large pale areas of RPE atrophy with patchy hyperpigmentation due to reactionary proliferation of the RPE
|
|
|
What might be the microscopic appearance of the sclera at the site of a silicone encircling band? Why?
|
Encircling silicone bands are biologically inert
Thus the adjacent scleral tissue may be free from inflammatory cell infiltration A thin strip of compressed sclera and choroid lined by proliferating RPE may separate the band from the retina |
|
|
What is the most common cause of failure in retinal detachment surgery? How is it recognised?
|
PVR
Recognised by a distorted, stiffened, and folded retina with or without detachment A pale membrane with patchy pigmentation may be identified on the inner surface of the retina |
|
|
What are the mechanisms underlying PVR?
|
Proliferation of glial and RPE cells, usually on inner retinal surface
RPE cells may also proliferate as strands or cords within the subretinal space RPE cells undergo metaplasia to fibroblast-like cells with contractile properties Resultant tissue fibrosis and contracture distorts the inner retina with further redetachment |
|
|
Macroscopic and microscopic features of PVR
|
Macro: thickened distorted retina; subretinal strands of proliferating RPE
Micro: outer retina is atrophic and clumps of RPE cells are present on inner surface; fibrous metaplasia of RPE and formation of contractile fibrous tissue |
|
|
What is the appearance of emulsified silicone oil in the retina? and AC?
|
Clusters of macrophages distended by silicone oil globules are present most commonly on the inner and outer surfaces and within the retina
A section through the angle will show a massive lipomacrophagic infiltrate in the iris stroma and TM; may also be in the endothelium |
|
|
How does an exudative retinal detachment appear after fixation? Histologically?
|
After fixation, appears as a solid brown proteinaceous gel beneath the retina
Histologically, exudate is pink with H&E |
|
|
What are the main histological features of the uveal effusion syndrome?
|
1. Detachment of the CB, choroid and retina by exudation
2. Absence of inflammatory or neoplastic disease 3. Thickening of the sclera 4. Ultimately, hypotonia and phthisis is due to CB shutdown from chronic detachment, which compromises the blood supply to the ciliary processes |
|
|
Useful immunohistochemical markers in sebaceous carcinoma
|
HMFG1 (human milk fat gloube)
EMA (ep mem antigen) identify central foamy cells MNF116 (cytokeratin) stains smalleral peripheral basal cells |
