title: Pilomatrixoma (benign calcifying epithelioma of Malherbe).
abstract: A 24-year-old white man had a large subcutaneous discolored tumefaction of the right lower lid, successfully treated by two separate incision and drainage procedures. Microscopic appearance initially suggested basal cell epithelioma, but further studies provided a correct diagnosis of pilomatrixoma (calcifying epithelioma of Malherbe). This lesion probably represents aberrant primitive germ cells differentiating towards a hair matrix cell. Basaloid and squamoid (shadow) cells with or without focal calcifications in shadow cell areas are typical, and the clinical presentation is also highly suggestive of pilomatrixoma.
mesh_terms: D000328:Adult; D002280:Basal Cell Carcinoma / Q000175:diagnosis; D003937:Diagnosis, Differential; D005142:Eyelid Neoplasms / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D008297:Male; D012878:Skin Neoplasms / Q000175:diagnosis / Q000473:pathology*