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75 Cards in this Set

  • Front
  • Back
What is a macule?
flat discoloration, < 1 cm
What is a patch?
flat discoloration, > 1 cm
What are causes of macules or patches?
hyperpigmentation, melanosis
hypopigmentation, leukoderma
hemorrhage, hyperemia
What is a plaque?

Give an example dz.
flat, solid, raised, > 1 cm

ex. feline eosinophilic plaques
What is a papule?

Give an example dz.
raised solid discoloration, < 1 cm

ex. bacterial folliculitis & furunculosis
What is a nodule?

Give an example dz.
raised, usually solid discoloration > 1 cm

ex. tumor, inflammation (granuloma), hyperplasia
What is a vesicle?
intra-epidermal/sub-epidermal pocket of fluid, < 1 cm
What is a bulla?
intra-epidermal/sub-epidermal pocket of fluid, > 1 cm (rare: often ruptures before you see it)
Give an example of a disease with vesicles &/or bullae.
epidermolysis bullosa
What is a pustule?

Give an example dz.
intra-epidermal vesicle filled w/ pus

rupture easily b/c of thin epidermis & present as erosions, ulcers, &/or crusts

ex. pemphigus foliaceus
What is scale?

Give an example dz.
↑ stratum corneum (hyperkeratosis): white, flaky

ex. sebaceous adenitis
What is crust?

Give an example dz.
desiccated accumulation of keratin, serum, cell debris, hemorrhage, &/or microorgs on skin surface

ex. superficial bacterial pyoderma
What is an erosion?
partial loss of epidermis (very thin)
What is an ulcer?
complete loss of epidermis thru basement mem
Name 2 dz characterized by erosions & ulcers.
erythema multiforme, vasculitis
What is lichenification?
thickening of skin & accentuation of skin surface markings, folds & lines (skin hyperplasia)
What is atrophy?

Give an example dz.
thinning of skin d/t loss of epidermal &/or dermal mass

Cushing's: epidermal, dermal, &/or follicular atrophy
To what depth does a punch biopsy sample?
superficial panniculus
To what depth does a shave biopsy sample?
superficial dermis
What are indications for a wedge or excisional bx?
-deep lesions
-fragile lesions
-whenever orientation is essential, esp. lesion margions
-to assess invasion (wedge or excisional)
What are indications for a shave bx?
used only for delicate areas (ear, nasal planum) to differentiate epidermal diseases
How would you bx small lesions such as papules, pustules, & vesicles?
-bx small lesions in entirety
-center small lesions w/in punch biopsy
-take several (6+) biopsies of very small lesions: label “section to center of bx”
-use a wedge bx for fragile lesions such as vesicles & pustules
How would you bx ulcers?
-use a deep wedge bx perpendicular to ulcer margin where possible
-bx epidermis at margin of ulcer, central blood vessels deep to ulcer
-avoid shallow biopsies in central ulcerated areas
-avoid punch biopsies: too shallow, hard to orient for sectioning
How would you bx alopecia?
-bx central, most developed areas of alopecia
-use 8mm punches & collect multiple (6) biopsies
-collect 1 bx from normally haired skin at a similar site, particularly for partial or subtle hair loss
-mark line of hair follicle growth prior to bx on areas w/ little hair left
How would you bx plaques, nodules, or masses?
-wedge biopsies from actively enlarging, inflamed margins
-bx large masses & plaques at margin
-excise small nodules completely
-avoid central scarring, necrosis, &/or superficial ulcers
How would you bx pannicular lesions?
wedge bx; biopsy center of lesion
How would you bx cutaneous hemorrhage?
-bx center of areas of hemorrhage
-wedge biopsies for large hemorrhages & when deep vascular lesions are suspected
-take multiple biopsies: vascular lesions can be small & very hard to hit in histological section
-confirm hemorrhage by diascopy
-R/O clotting abnormalities prior to bx
How would you bx leukoderma?
-seek areas of recent leukoderma (hx) w/ erythema (active)
-bx active areas of luekoderma at lesion margin
How would you bx leukotrichia?
bx multiple central areas similar to methods used for alopecia, margins if active depigmentation
What types of skin dz are assoc. w/ neutrophils?
bacterial pyoderma, pemphigus
What types of skin dz are assoc. w/ eosinophils?
hypersensitivity (atopy, FAD, food allergy), parasites, some fungus, oomycetes (Pythium)
What types of skin dz are assoc. w/ mast cells?
hypersensitivity, chronic dermal fibrosis (lichenified skin), numerous in normal dermis
What types of skin dz are assoc. w/ macrophages?
chronic inflammation, fungal, oomycetes, mycobacterium, foreign body
What types of skin dz are assoc. w/ lymphocytes & plasma cells?
chronic inflammation, autoimmune
perivascular dermatitis

a. what is it?
b. causes
a. inflammatory cells accumulate around reactive blood vessels; most common pattern of inflammation, least diagnostic
b. neutrophilic: R/O bacterial
-eosinophilic: hypersensitivities (atopy, food allergy, FAD), ectoparasites, etc
interface dermatitis

a. what is it
b. causes
c. lesions
a. inflammatory cells (cytotoxic T cells) target basal keratinocytes --> basal keratinocyte degeneration (ballooning change) & individual cell death (apoptosis)
mediated by lymphocytes
cell rich type: cytotoxic T cells target basal keratinocytes
cell poor type: chronic dermal ischemia --> basal cell death
b. most are autoimmune
Lupus tissue rxns: discoid lupus, systemic lupus
erythema multiforme complex: drug rxns, post infection?
chronic ischemic dermatopathies: dermatomyositis, rabies vaccine assoc. alopecia, chronic vasculitis of varied causes
VKH-like syndrome: targets mostly melanocytes
some epidermal viral infections
c. shallow ulcers & erosions, depigmentation, vesicles when severe basal cell death (rare), epidermal atrophy (chronic nasal planum lesions)

a. what is it
b. causes
c. sites commonly affected
a. inflammation targets vessels w/ damage to vessel walls (necrosis, fibrin deposition, hemorrhage)
b. tick borne dz (RSMF, etc.), sepsis, drug rxns, systemic lupus, equine purpura hemorrhagica, hypersensitivity (rare)
c. ear tips/margins, footpads, oral cavity, scrotum, pressure points, tail tip
nodular & diffuse dermatitis

a. what is it
b. causes
a. inflammatory cells form nodules which may coalesce to produce diffuse infiltrates
b. R/O infectious causes 1st: remember to CULTURE!
bacterial: Mycobacteria, Nocardia, Actinomyces
fungal: Blasto, Crypto
foreign body rxns
Oomycetes: Pythium, Lagendium
neoplasms can also present as nodules & masses
intraepidermal vesicular & pustular dermatitis

a. what is it
b. causes
a. intraepidermal structures break down --> acantholysis --> formation of intraepidermal vesicles, bullae, &/or pustules
acantholysis: keratinocytes separate & become more round than normal
b. superficial bacterial pyoderma/impetigo
pemphigus foliaceus
pemphigus vulgaris: uncommon
dermatophytosis: uncommon presentation
early stages of some viral infections: often progress quickly to erosions or ulcers
subepidermal vesicular & pustular dermatitis

a. what is it
b. causes
a. subepidermal (basement membrane) structures break down --> separation of epidermis from dermis --> subepidermal vesicles, bullae, &/or pustules
b. autoimmune blistering dz (middle aged animals): autoAb target BM proteins; bullous pemphigoid, mucus membrane pemphigoid, epidermolysis bullosa aquisita

hereditary blistering dz (young animals): genetic defect in a protein in BM; dystrophic epidermolysis bullosa, junctional epidermolysis bullosa
perifolliculitis, folliculitis, furunculosis

a. what are they
b. causes
c. lesions
a. perifolliculitis: inflammatory cells accumulate in dermis around hair follicle but do not enter
folliculitis: inflammatory cells infiltrate epithelial wall &/or lumen of hair follicle
furunculosis: rupture of hair follicle, usually in assoc. w/ folliculitis
b. bacteria (Strep intermedius), dermatophytosis, Demodex
c. papules &/or nodules

a. what is it
b. causes
a. inflammatory cells infiltrate pannicular septa (CT) &/or lobules of fat
b. assume infectious until proven otherwise --> tx w/ AB’s 1st
idiopathic sterile nodular panniculitis
pancreatitis or pancreatic neoplasia: release of pancreatic enzymes --> fat breakdown --> inflammation (rare)
post injection panniculitis: focal rxn d/t vaccine administration, some drugs
atrophic dermatitis

a. what is it
b. causes
a. atrophic changes in hair follicles (--> alopecia) & less often in dermis & epidermis
NOT an inflammatory lesion
b. endocrinopathies (ex. Cushing's, steroid administration, hypothyroidism, sex hormone related)
chronic ishemic dermatopathies: dermatomyositis, rabies vax assoc. panniculitis & alopecia
What are hemidesmosomes?
connect epidermal basal keratinocytes to BM, which connects to dermal collagen
What is the epidermal basement membrane?
sheet-like meshwork of proteins that connects epidermis to dermis

a. layers
b. cell types
a.stratum corneum, stratum granulosum, stratum spinosum, stratum basale
b. keratinocytes (~85%), melanocytes, Langerhans cells (skin MPs), lymphocytes (few migrating thru)
What are keratin intermediate filaments?
connect keratinocytes together via desmosomes in cell mem: meshwork that holds cells together
acquired skin fragility

a. species affected
b. cause
a. cat
b. 2º to steroid tx (atrophy of dermal collagen), Cushing’s (rare)
solar injury

a. results of sustained solar injury
b. what is solar keratosis
a. solar dermatitis (sun burn) --> solar keratosis --> SCC
b. ex. dog abdomen (epidermal hyperplasia & dysplasia, vascular injury to superficial dermis)

a. primary
b. secondary
c. pathogenesis
a. preformed photodynamic agent ingested (ex. plants) or administered (drugs)
b. hepatic dz impairs excretion of phylloerythrin, a product of chlorophyll formed in GI tract
c. photodynamic agent (chromophore) circulates to skin --> sun actives agent --> reactive oxygen intermediates --> superficial vascular & skin necrosis --> ulcers & crusting of white, sun exposed areas
What are some skin diseases that are exacerbated by sun exposure?
pemphigus foliaceus
discoid lupus erythematosis
vesicular cutaneous lupus
superficial pyoderma

a. part of skin involved
b. lesions
c. examples
a. epidermis & upper infundibulum of hair follicles
b. erythema, alopecia, papules, pustules, crusts, epidermal collarettes
c. superficial pustular dermatitis (impetigo), superficial spreading pyoderma, Dermatophilosis, greasy pig dz (exudative epidermitits)
deep pyoderma

a. part of skin involved
b. example
a. hair follicle, dermis, &/or subcutis
b. staphylococcal folliculitis & furunculosis

a. part of skin involved
b. lesions
a. infect & grow in cornified layers (keratophilic): stratum corneum, hair shafts, occ. claws
b. circular areas of alopecia, scaling, papules w/ folliculitis, sometimes nodules (kerion) d/t coalescing rupture of hair follicles (furunculosis)
feline ulcerative facial dermatitis & stomatitis

a. etiology
b. lesions
a. feline herpesvirus
b. asymmetrical alopecia, often assoc. w/ mucus membranes

a. etiologic agent
b. part of skin infected
c. 2 forms
d. dx
a. Demodex canis
b. lives in follicle lumen (most normal dogs have some mites)
c. localized: small patches of alopecia
generalized: 5 or more localized regions or over whole body
-may be d/t immunosuppression in adults
-susceptible to bacterial infection --> generalized pustular demodicosis
d. hair plucking, deep skin scrape

a. etiologic agent
b. part of skin infected
c. lesions
a. Sarcoptes scabei
b. lives in epidermis: tunnels & deposits eggs --> epidermal hyperplasia (lichenification)
c. small # of mites --> severe lesions d/t self trauma, hypersensitivity (extremely pruritic)
What are the 2 things that must happen for a hypersensitization rxn to occur?
1st: sensitization phase to an allergen

2nd: elicitation phase after subsequent allergen challenge = exaggerated immune response assoc. w/ clinical signs
pemphigus foliaceus

a. pathogenesis
b. distribution of lesions
a. autoAbs disrupt attachments (desmosomes) b'twn keratinocytes (acantholysis)
b. symmetric lesions on face, ears, footpads
often see crusting d/t drying up of pustules
pemphigus vulgaris

a. pathogenesis
b. distribution of lesions
a. acantholysis right above basal cell layers --> deep erosions, ulcers
b. oral cavity
Name 3 autoimmune skin diseases that target the BM & describe the distribution of lesions for each.
bullous pemphigoid
-distribution: skin, oral cavity, ears
-lesions: deep erosions, ulcers

mucus membrane pemphigoid
-distribution: mucocutaneous junctions (nose, eyes, oral cavity, genitalia)

epidermolysis bullosa acquisita
-distribution: skin, foot pads
-lesions: vesicles & bullae
VKH-like syndrome

a. pathogenesis
b. lesions
a. lymphocytes target melanocytes
b. periocular & nasal depigmentation, uveitis --> blindness
What skin lesions are associated w/ Cushing's?
truncal alopecia, comedones, scaling, dry hair coat, variable thinning of skin, often 2º bacterial pyoderma, hyper- or hypo- pigmentation

dogs: calcinosis cutis
horses: hirsutism
canine zinc responsive dermatosis: syndrome I

a. signalment
b. cause
c. lesions
a. Siberian Huskies, Alaskan Malamutes
b. defect in Zn absorption --> diffuse parakeratosis: retention of nuclei in stratum corneum
c. scale, hyperkeratosis, crusting on face, pressure points, foot pads, ear tips, around eyes, eyes mouth
canine zinc responsive dermatosis: syndrome II

a. signalment
b. causes
c. lesions
a. puppies, esp. large breed
b. relative zinc deficiency, rapidly growing animals; low zinc, high calcium, &/or high phytates
c. scale, hyperkeratosis, crusting on face, pressure points, foot pads, ear tips, around eyes, eyes mouth
primary seborrhea

a. primary lesion & cause
b. dx
c. sequelae
a. defect of keratinization --> scaling (hyperkeratosis): may be dry or oily
b. idiopathic: dx of exclusion (uncommon)
c. secondary bacterial infection
secondary seborrhea

a. primary lesion
b. causes
c. sequelae
a. primarily epidermal hyperplasia, NOT epidermal
b. occurs 2º to some other inflammatory problem in skin (common)
c. secondary bacterial infection
sebaceous adenitis

a. pathogenesis
b. signalment
c. lesions
a. proposed keratinization defect or immune mediated
b. standard poodles, vizslas, Samoyeds, akitas, chows
c. inflammation targets sebaceous glands --> lots of scaling +/- significant alopecia
What are some causes of hyperkeratosis of the nasal planum & footpads in dogs?
distemper (hard pad dz), pemphigus foliaceus (hyperkeratosis, crusting from pustules), zinc responsive dermatosis, idiopathic or familial in some dogs, hepatocutaneous syndrome (hyperkeratosis, crusting)
pancreatic paraneoplastic syndrome

a. species affected
b. cutaneous lesions
c. non-cutaneous lesions
a. cat
b. shiny skin, ventral alopecia, fissures & redness on paws
c. anorexia, cachexia, lethargy, abdominal distension
exfoliative dermatitis & thymoma

a. cutaneous lesions
b. non-cutaneous lesions
a. lymphocytes target epidermis --> redness, scaling, patchy alopecia of head, neck, ears
b. coughing, respiratory distress, anorexia, muscle wasting
hepatocutaneous syndrome

a. cause
b. lesions
c. sequelae
a. severe liver dz
b. scaling, crusting: usually symmetrical
c. 2º infection common: bacteria, Candida, Malasezzia
pancreatic panniculitis (necrotizing panniculitis, pansteatitis)

a. species affected
b. causes
c. lesion
a. cat
b. pancreatic neoplasia, nutrition possible (↑ unsaturated fatty acids in diet, ↓ Vit. E)
c. fat necrosis --> inflammation (steatitis)
cutaneous hemangioma/HSA

a. may be associated w/?
b. layers of skin affected
a. may be solar associated on ventral abdomen of thin haired dogs
b. deep into panniculus, skeletal muscle or can be very superficial
cutaneous melanomas: locations & assoc. behavior

a. dogs
b. gray horses
a. most on haired skin are benign, those on claw bed or in oral cavity are often malignant
b. perineal, tail, prepuce --> lymph node, systemic involvement (slowly progressive)