Abstract

Induction of cutaneous hyperplasia can be a helpful histologic clue for diagnosing underlying dermal lesions or a potential diagnostic pitfall. We present a unique case of angioleiomyoma with induction of epidermal hyperplasia and a case of focal cutaneous mucinosis with follicular induction to discuss the implications of cutaneous induction. A 35 year-old man with a history of HIV presented to dermatology with a chronic non-tender 3 cm subcutaneous firm violaceous nodule on the left elbow. A punch biopsy showed epidermal hyperplasia with flattened rete ridges and dermal edema overlying the superficial aspect the dermal lesion. The lesion was composed of bland spindle cells with blunt-ended nuclei and pale pink cytoplasm and contained thick-walled vessels. Lesional cells expressed SMA and were negative for HHV-8. The findings were compatible with a superficially sampled angioleiomyoma with epidermal induction. The second case is that of a 40 year-old woman referred to dermatology for evaluation of a fleshy pink 1 cm plaque on the left breast of one year’s duration. A shave biopsy revealed a collection of mucin in the superficial dermis, highlighted by a colloidal iron stain. The overlying epidermis demonstrated focal aggregates of basaloid cells with peripheral palisading protruding from the base of the epidermis. A diagnosis of focal cutaneous mucinosis with follicular induction was rendered. Induction of cutaneous hyperplasia results from interactions between stroma and epithelium and occurs in neoplastic and regenerative settings. Awareness of this phenomenon and associated neoplasms are essential for dermatopathologists to avoid misdiagnosing a dermal process as a primary epithelial lesion. From our observations, an angioleiomyoma may be associated with cutaneous induction. Dermatopathologists can leverage epidermal induction to investigate for underlying dermal processes, especially in superficial biopsies which may not sample the entire lesion of interest.

Financial Disclosure:
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