IMMUNOHISTOCHEMICAL STUDY OF TESTICULAR SEX CORD-STROMAL TUMORS, INCLUDING STAINING WITH ANTI-INHIBIN ANTIBODY

Inhibin is a peptide hormone produced by ovarian granulosa cells and t esticular Sertoli cells. Ovarian granulosa cell and other sex cord-str omal tumors usually exhibit positive immunohistochemical staining with antiinhibin antibodies, and this may be valuable in differentiating t hese neoplasms from histologic mimics. In the present study, we invest igated the immunohistochemical staining of testicular sex cord-stromal tumors using antiinhibin. Immunostaining with CAM5.2, vimentin, S-100 protein, desmin, epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), and placental alkaline phosphatase (PLAP) also was perf ormed because few studies have investigated in detail the immunophenot ype of testicular sex cord-stromal tumors. Fifteen of 16 Leydig cell t umors exhibited strong positive staining with antiinhibin. A proportio n of Leydig cell tumors also stained positively with CAM5.2 (7 of 16), vimentin (14 of 16), S-100 protein (10 of 16), desmin (2 of 16) and e pithelial membrane antigen (4 of 16). Four of six testicular sex cord- stromal tumors with varying degrees of Sertoli or granulosa cell diffe rentiation were positive with antiinhibin, as were two of three sex co rd-stromal tumors that were unclassified. Some of these tumors were po sitive with CAM 5.2, vimentin, S-100 protein, desmin, and epithelial m embrane antigen. Ail tumors were negative with carcinoembryonic antige n and placental alkaline phosphatase. The immunohistochemical findings show that, analogous to their ovarian counterparts, most testicular s ex cord stromal tumors are immunoreactive with antiinhibin. Immunohist ochemistry using this antibody as part of a panel may be valuable in c onfirming a diagnosis of testicular sex cord-stromal tumor and in diff erentiating these neoplasms from others that may mimic them.