Microcystic adnexal carcinoma with multiple areas of follicular differentiation toward germinative cells and specific follicular stroma (trichoblastomatous areas).

We present a case of microcystic adnexal carcinoma (MAC) occurring on the upper lip of a 63-year-old man, which, in addition to the predominant areas of a conventional MAC, manifested multiple foci of follicular differentiation resulting in trichoblastomatous appearances. Some areas were highly reminiscent of desmoplastic trichoepithelioma (columnar trichoblastoma). We also reviewed 24 cases of MAC in our files, but in none of the cases were similar features observed, indicating that such histopathological findings are rare in MAC.