Skin, Spiradenoma

Spiradenomas are benign adnexal (sweat gland) neoplasms of the skin. They usually present in young adults as painful, solitary firm nodules on the face and upper trunk. Histologically, spiradenomas are well-circumscribed dermal-based tumours composed of two populations of epithelial cells forming nests and cords: 1) dark cells which are small, basaloid with hyperchromatic nuclei located at the periphery, and 2) pale cells which are larger with vesicular nuclei and ample pale cytoplasm, which tend to be near the centre of the clusters. PAS positive globules, derived from basement membrane material, may be seen throughout the neoplasm.