Cytologic detection of Call-Exner bodies in Sertoli cell tumors from 2 dogs.

A 14-year-old Italian Griffon and an 11-year-old mixed breed dog were presented to our clinic with monolateral testicular enlargement. In both dogs, a firm, nodular, and nonpainful mass was palpated, and ultrasonographic examination of testicular parenchyma showed a large and irregular nodular area with hyperechogenic features. Fine-needle aspirates of the masses were highly cellular and consisted of populations of large elongated vacuolated cells in sheets and palisades, with finely granular chromatin and prominent nucleoli, consistent with neoplastic Sertoli cells. A variable number of structures also were observed that consisted of a central round area of amorphous, deeply eosinophilic, hyaline material surrounded by a peripheral, rosette-like arrangement of single or multiple rows of Sertoli cells. These structures were suggestive of Call-Exner bodies. Histologic sections of the tumors obtained following castration confirmed the diagnosis of Sertoli cell neoplasia and the presence of Call-Exner bodies. The Call-Exner bodies were intensely positive with PAS, toluidine blue, and Ziehl-Neelsen stains, moderately positive with alcian blue, and negative with Congo red and Luxol fast blue. Call-Exner bodies, thought to represent an attempt by neoplastic cells to form basement membrane, are seen most frequently in granulosa cell tumors, but are occasionally reported in testicular tumors that contain epithelial elements of sex-cord origin. To our knowledge, this is the first description of Call-Exner bodies in cytologic specimens from dogs, and only the fifth report of their presence in canine testicular neoplasms.