Apocrine adenomyoepithelioma--a rare but distinctive primary sweat gland neoplasm.

Adenomyoepithelioma is a rare, microscopically distinctive tumor of the skin. This article explores an example that presented in the inguinal area in a 29-year-old woman, mimicking adenopathy. Histopathologically, the tumor included two different areas: a cystic area consisting of tubules and glands in hyalinized stroma and a solid area showing marked myoepithelial proliferation. The diagnosis of adenomyoepithelioma was confirmed by the presence of a biphasic immunoprofile, with expression of cytokeratins and epithelial membrane antigen in the glandular epithelium and with expression of vimentin and smooth muscle actin in the myoepithelial cells. An interesting novel finding was the expression of claudin-10 by myoepithelial cells, which to date has not been reported in the literature. The absence of metaplastic changes in the tumor stroma is crucial in the differential diagnosis with apocrine mixed tumor. Given that soft tissue adenomyoepithelioma is a benign tumor believed to originate from conventional sweat glands, its classification as a cutaneous myoepithelial neoplasm seems reasonable.