MULLERIAN-INHIBITING SUBSTANCE, ALPHA-INHIBIN, AND CD99 EXPRESSION INSEX CORD-STROMAL TUMORS AND ENDOMETRIOID OVARIAN CARCINOMAS RESEMBLING SEX CORD-STROMAL TUMORS

Mullerian inhibiting substance (MIS), alpha-inhibin, and CD99 are expr essed by normal and neoplastic sex cord and stromal gonadal derivative s. The expression of MLS, inhibin, and CD99 was evaluated by immunohis tochemistry in a series of 19 sex cord-stromal tumors and seven ovaria n endometrioid carcinomas resembling sex cord-stromal tumors. Normal o varies and testes from patients with the androgen insensitivity syndro me were used as control. All three markers were detected in primordial ovarian follicles and immature seminiferous tubules. Both inhibin and MIS were expressed by all sex cord-stromal tumors, but inhibin immuno staining appeared stronger and more diffusely distributed. CD99 was ex pressed by all adult and juvenile granulosa cell tumors, but only foca lly by Sertoli-Leydig cell tumors. In Sertoli-Leydig cell tumors, the three markers were predominantly expressed by the Sertoli cells. None of the seven endometrioid carcinomas with a sex cord-stromal pattern w as positive for MIS or inhibin; two of them reacted for CD99, but thei r staining patterns were not membranous. Inhibin immunoreactivity was also detected in foci of stromal luteinization, occasionally present i n these tumors. MIS, inhibin, and CD99 are potentially useful markers in the differential diagnosis between sex cord-stromal tumors and endo metrioid carcinomas resembling sex cord-stromal tumors. Copyright (C) 1998 by W.B. Saunders Company.