[An adenoid tumor of the epididymis--electron microscopy and immunohistochemistry]

A case of an adenomatoid tumor of the epididymis is reported. The patient, a 41-year-old male, had a total right orchiectomy of his testicular mass. The tumor was located in the inferior portion of the right epididymis and was a well-circumscribed solitary mass, measuring 3 X 3 X 3 cm. Microscopically, the tumor contained plump acidophilic cells arrange in cords and trabecula with fibrous connective tissue. Immunohistochemical studies for keratin and vimentin in the tumor cells were positive. Electron microscopical findings of the tumor were similar to those of a benign mesothelioma. These findings suggest that adenomatoid tumors are of mesothelial origin.