Acinic Cell Adenocarcinoma Arising in the Breast of a Young Male: A Clinicopathological, Immunohistochemical and Ultrastructural Study.

A 23-year-old man with acinic cell adenocarcinoma of the breast is reported. He presented with a 4.8 x 4.2 cm mass in his left breast, and excisional biopsy was performed. Under the light microscope, tumor cells had abundant periodic acid-Schiff-positive secretory granules and eosinophlic cytoplasms. Electron microscopy revealed the granules to have various electron densities, a finding characteristic of acinic cell adenocarcinoma. Immunohistochemically, the tumor cells were stained with salivary-type amylase. Electron microscpic and immunohistochemical investigation greatly facilitated the diagnosis of this acinic cell adenocarcinoma, which was in an unusual location. We believe this is the first case report of acinic cell adenocarcinoma of the mammary gland studied utilizing light microscopic, ultrastructural and immunohistochemical techniques.