A complex poroma-like adnexal adenoma.

Hidroacanthoma simplex, eccrine poroma, and dermal duct tumor are benign adenomas that develop from excretory ducts of eccrine glands and all three are variants of eccrine acrospiroma. To date, counterparts in apocrine or sebaceous glands have not been reported, but in this study we describe an adnexal, poroma-like adenoma that showed apocrine and sebaceous differentiations. Apocrine structures have the same embryonic origin as does the pilosebaceous system; both are derived from the primary epithelial germ. We suggest that the lesion we describe is truly a sebaceous and apocrine poroma. It must be distinguished from an infundibular adenoma whose pattern reproduces that of follicular poroma.