Benign tumors Fibrous Papule Definition A benign proliferation in the superficial dermis, composed of fibroblasts, blood vessels, and sparse inflammatory cell infiltrate in the background of a sclerotic dermal collagen Multiple lesions can be associated with tuberous sclerosis and, less…
Benign fibroblastic and myofibroblastic tumors Hypertrophic Scar Definition A reactive proliferation of fibroblasts/myofibroblasts confined to the boundaries of the wound forming short fascicles, whorls, or nodules, typically lacking keloidal collagen Generally associated with previous local trauma or burns Clinical features…
Benign tumors and reactive conditions Lipoma Definition A benign dermal or subcutaneous mesenchymal tumor composed of mature adult-type adipose tissue Clinical features Epidemiology The most commonly encountered mesenchymal tumor Majority of patients are adults No sex predilection Presentation Most cases…
1 Electrocautery Keratinocytes show marked parallel vertical elongation Homogenization of the collagen 2 Gelfoam Blue-purple, arabesque, netlike pattern with surrounding granulomatous reaction 3 Aluminum chloride Epidermal effacement and horizontal fibrosis consistent with scar and underlying light gray-blue granules, often in…
1 Desmosome A classic desmosome showing the following features: (1) uniform gap of 20–30 nm between the apposed trilaminar plasma membranes with an intermediate line (arrow) in this gap; and (2) sharply delineated dense plaques into which tonofibrils (F) converge. 2…
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It is important to distinguish cutaneous metastases, particularly metastatic adenocarcinoma, from primary adnexal tumors of the skin. Adenocarcinoma metastatic to the skin is commonly of breast or lung origin. Focal areas of glandular differentiation may be highlighted with a mucicarmine…
Cutaneous B-cell lymphoproliferative disorders The primary cutaneous B-cell lymphomas share some histologic features with their nodal counterparts, but in many cases represent distinct clinicopathologic entities with significant clinical, immunophenotypic, molecular, and prognostic differences from their extracutaneous counterparts. In general, primary…
Cutaneous T-cell lymphoma and NK-cell lymphoma Mycosis fungoides Patch stage Key Features Lymphocytes “line up” along the dermal–epidermal junction (simulates vacuolar interface dermatitis, with a “lymphocyte in every hole”) Large dark lymphocytes with irregular nuclear contours and perinuclear haloes (“lump…
Angiokeratoma Key Features Hyperkeratosis Acanthosis Ectatic, thin-walled vessels in contact with the epidermis Resembles a “bloody seborrheic keratosis” Lymphangioma Key Features “Frog spawn” clinically Similar to angiokeratoma with lymph in vessels, but few erythrocytes D2-40+ Nevus flammeus Key Features Dilated…