Pure apocrine nevus. A study of light-microscopic and immunohistochemical features of a rare tumor

The pure apocrine nevus is a rare tumor. A new case of pure apocrine nevi of the bilateral axillary regions in a 48-year-old man is herein reported. The patient had two soft masses of both axillae. The time of onset of the masses was unknown. They were not accompanied by problems of sweating. Histologically, these lesions comprised numerous apocrine glands extending from the reticular layer of the dermis to the subcutaneous tissue. In addition, sections from both of the lesions were stained by immunoperoxidase techniques for the presence of epithelial membrane antigen, carcinoembryonic antigen, and the alpha and beta subunits of S100 protein. Immunohistochemical features of the tumor stained by these antibodies are consistent with a pure proliferation of mature, well-differentiated apocrine glands. The tumor of the present case seems to have developed spontaneously. It is believed, therefore, that the tumor seen in this patient is best categorized as a pure apocrine nevus.