Adenocarcinoma of the mammary-like glands of the vulva: a concept unifying sweat gland carcinoma of the vulva, carcinoma of supernumerary mammary glands and extramammary Paget's disease.

An unusual case of primary adenocarcinoma of the vulva is described. It combined features of the three different types of adenocarcinoma of the skin of the vulva which are currently recognized, i.e. sweat gland carcinoma, adenocarcinoma derived from supernumerary mammary glands, and extramammary Paget's disease (EMPD). Central in this tumor was a recently recognized type of cutaneous gland which appeared special for the anogenital region and was distinguished because it combined morphological features of eccrine, apocrine and mammary glands. As it most resembles mammary glands, it is named "mammary-like gland". On the basis of the case presented and of a critical review of the literature, it was concluded that, with the exception of a few sweat gland carcinomas similar to those elsewhere in the skin, adenocarcinomas of the skin of the vulva form a single category of neoplasms with a variable expression of features reminiscent of eccrine, apocrine and mammary gland carcinomas. The data strongly suggested a common derivation from the mammary-like gland or, in cases of EMPD, its related germinative cells in the epidermis.