Microcystic adnexal carcinoma with sebaceous differentiation: three cases

Abstract

Microcystic adnexal carcinoma (MAC) is a low-grade malignant tumor of the skin. Histologically, this tumor shows a biphasic pattern, with cords and nests of basaloid cells, as well as keratin horn cysts. This biphasic histological appearance has been interpreted by some authors as a sign of double eccrine and folliculosebaceous-apocrine differentiation, whereas some other authors defend an solely eccrine differentiation. In this context, sebaceous differentiation in MAC would support the first option. However, there are only three cases of MAC with sebaceous differentiation in the literature, and all of them are previous to adipophilin, which in the appropriate context (for example testing clear cells for sebaceous versus eccrine differentiation) is very useful. In the current paper, we present three cases of MAC with focal sebaceous differentiation confirmed by inmmunoexpression of adipophilin in the sebaceous foci.