OVARIAN ENDOMETRIOID CARCINOMAS SIMULATING SEX CORD-STROMAL TUMORS - A STUDY USING INHIBIN AND CYTOKERATIN-7

We have investigated the use of inhibin and cytokeratin-7 (CK-7) in di stinguishing endometrioid ovarian carcinomas (both typical and sex cor d-like) from granulosa cell and Sertoli cell-containing ovarian tumors . Immunohistochemical staining with inhibin, CK-7, and epithelial memb rane antigen (EMA) was performed on 6 endometrioid carcinomas simulati ng sex cord-stromal tumors, 5 typical endometrioid carcinomas, 14 adul t granulosa cell tumors (AGCTs), 3 Sertoli-Leydig cell tumors (SCLTs), and 1 sex cord tumor with annular tubules (SCTAT). All AGCTs and SLCT s as well as the SCTAT were inhibin-positive. In contrast, all of the endometrioid carcinomas (both typical and those mimicking sex cord-str omal tumors) were inhibin-negative. CK-7 expression was not observed i n the granulosa cell tumors and it was noted only in retiform areas in SLCTs. All 5 typical endometrioid carcinomas and 5 of the 6 sex cord- like endometrioid carcinomas were CK-7 positive. EMA was positive in a ll carcinomas but negative in the SCTAT, AGCTs, and SLCTs. Inhibin can distinguish between sex cord-stromal tumors (whether granulosa or Ser toli-Leydig type) and endometrioid carcinomas. CK-7 is also helpful in differentiating between AGCTs and most endometrioid carcinomas, and m ay also aid in separating SLCTs from sertoliform carcinomas. The addit ion of inhibin to an antibody panel is important because it provides a positively-staining marker for sex cord-derived cells.