Dermatology Pictures: Gross And Histology

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Acute Eczematous Dermatitis

- Microscopically, there is fluid accumulation (spongiosis) between epidermal cells that can progress to small vesicles if intercellular connections are stretched until broken.

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Acute Eczematous Dermatitis

- The patterned erythema and scale stems from a nickel-induced contact dermatitis produced by this woman’s necklace.

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Erythema Multiforme

- Early lesions show a collection of lymphocytes along the dermoepidermal junction (interface dermatitis) associated with scattered keratinocytes with dark shrunken nuclei and eosinophilic cytoplasm that are undergoing apoptosis.

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Erythema Multiforme

- The target-like lesions consist of a pale central blister or zone of epidermal necrosis surrounded by macular erythema.

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Psoriasis

- Microscopic examination reveals marked epidermal hyperplasia, uniform downward extension of rete ridges (psoriasiform hyperplasia), and prominent parakeratotic scale that is focally infiltrated by neutrophils.

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Psoriasis

- Chronic plaques of psoriasis show silvery-white scale on the surface of erythematous plaques.

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Lichen Planus

- Microscopic features include a bandlike infiltrate of lymphocytes along the dermoepidermal junction, hyperkeratosis, hypergranulosis, and pointed rete ridges (“sawtoothing”), which results from chronic injury of the basal cell layer.

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Lichen Planus

- This flat-topped pink-purple polygonal papule has white lacelike markings referred to as Wickham striae.

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Lichen Simplex Chronicus

-Lichen simplex chronicus. Acanthosis with hyperkeratosis and hypergranulosis are distinctive. Clubbed Rete ridges, superficial dermal fibrosis and vascular ectasia, all common features, also are present.

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Impentigo

- Impetigo. This child’s arm is involved by a superficial bacterial infection producing the characteristic erythematous scablike lesions crusted with dried serum.

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Verruca Vulgaris

- Multiple warts, with characteristic rough, pebble-like surfaces.

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Verruca Vulgaris

- Microscopically, common warts contain zones of papillary epidermal proliferation that often radiate symmetrically the points of a crown (top). Nuclear pallor, prominent keratohyalin granules, and related cytopathic changes are seen at higher
magnification (bottom).

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Pemphigus Vulgaris

- There is uniform deposition of immunoglobulin and complement (green) along the cell membranes of keratinocytes in a characteristic “fishnet” pattern.

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Pemphigus Foliaceus

- Immunoglobulin deposits are confined to superficial layers of the epidermis.

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Pemphigus Vulgaris

- This erosion on the leg represents a group of confluent, “unroofed” blisters.

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Pemphigus Vulgaris

- Suprabasal acantholysis results in an intraepidermal blister in which rounded, dissociated (acantholytic) keratinocytes are plentiful (inset).

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Bullous Pemphigoid

- Deposition of IgG antibody detected by direct immunofluorescence as a linear band outlining the subepidermal basement membrane zone (epidermis is on the left side of the fluorescent band).

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Bullous Pemphigoid

- Gross appearance of characteristic tense, fluid-filled blisters.

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Bollous Pemphigoid

- A subepidermal vesicle with an inflammatory infiltrate rich in eosinophils.

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Dermatitis Herpetiformis

- Selective deposition of IgA autoantibody at the tips of dermal papillae is characteristic.

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Dermatitis Herpetiformis

- Lesions consist of intact and eroded (usually scratched) erythematous blisters, often grouped (seen here on elbows and arms).

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Dermatitis Herpetiformis

- The blisters are associated with basal cell layer injury, initially caused by accumulation of neutrophils (microabscesses) at the tips of dermal papillae.

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Seborrheic Keratosis

- This roughened, brown, waxy lesion almost appears to be “stuck on” the skin (inset). Microscopic examination shows the lesion to consist of an orderly proliferation of uniform, basaloid keratinocytes that tend to form keratin microcysts (horn cysts).

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Actinic Keratosis

- Most lesions are red and rough (sandpaper like), owing to excessive scale, as seen in the lesions on the cheek, nose, and chin of this female patient.

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Actinic Keratosis

- Basal cell layer atypia (dysplasia) with epithelial buds, and associated with marked hyperkeratosis, parakeratosis, and dermal solar elastosis (asterisk).

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Actinic Keratosis

- More advanced lesions show full-thickness atypia, qualifying as squamous carcinoma in situ.

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Squamous Cell Carcinoma

- A nodular, hyperkeratotic lesion occurring on the ear, associated with metastasis to a prominent postauricular lymph node (arrow).

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Squamous Cell Carcinoma

- The tumor invades the dermis infiltrating collagen as irregular projections of atypical squamous cells, which in this case exhibit acantholysis.

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Basal Cell Carcinoma

- A prototypical pearly, smooth-surfaced papule with associated telangiectatic vessels.

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Basal Cell Carcinoma

- The tumor is composed of nests of basaloid cells infiltrating a fibrotic stroma.

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Basal Cell Carcinoma

- The tumor cells have scant cytoplasm and small hyperchromatic nuclei that palisade on the outside of the nest. The cleft between the tumor cells and the stroma is a highly characteristic artifact of sectioning.

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Junctional Nevi

- Tan macules with uniform colors and borders.

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Intradermal Nevi

- Skin- colored dome-shaped papules.

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Melanocytic Nevus

- This nevus shows rounded melanocytes that lose their pigmentation and become smaller and more separated as they extend into the dermis -all signs of cellular senescence that speak to the benign nature of the proliferation.

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Dysplastic Nevis

- Numerous irregular nevi on the back of a patient with the dysplastic nevus syndrome. The lesions usually are greater than 5mm in diameter and have irregular borders and variable pigmentation (inset).

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Dysplastic Nevis

- Compound dysplastic nevi feature a central dermal component with an asymmetric “shoulder” of exclusively junctional melanocytes (lentiginous hyperplasia). The former corresponds to the more pigmented and raised central zone (see A, inset), and the latter, to the less pigmented flat peripheral rim.

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Dysplastic Nevis

- Other important features are cytologic atypia
(irregular, dark-staining nuclei) and characteristic parallel bands of fibrosis—part of the host response to these lesions.

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Melanoma

- On clinical evaluation, lesions tend to be larger than nevi, with irregular contours and pigmentation. Macular areas indicate early superficial (radial) growth, while elevated areas often indicate dermal invasion (vertical growth).

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Melanoma

- Radial growth phase, with spread of nested and single-cell melanoma cells within the epidermis.

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Melanoma

- Vertical growth phase, with nodular aggregates of infiltrating tumor cells within the dermis (epidermis is on the right).

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Melanoma

- Melanoma cells have hyperchromatic nuclei of irregular size and shape with prominent nucleoli. Mitoses, including atypical forms such as seen in the center of this field, often are encountered. The inset shows a sentinel lymph node containing a tiny cluster of metastatic melanoma cells (arrow), detected by staining for the melanocytic marker HMB-45.