DIAGNOSTIC-VALUE OF INHIBIN IMMUNOREACTIVITY IN OVARIAN GONADAL STROMAL TUMORS AND THEIR HISTOLOGICAL MIMICS

Aims: Inhibin is a heterodimeric protein hormone which appears to be a sensitive serological and immunohistochemical marker of ovarian granu losa cell tumours. The purposes of this study were to examine inhibin immunoreactivity in a wide range of gonadal stromal neoplasms and to a ssess its value in the differential diagnosis of problematic ovarian t umours. Methods and Results: Inhibin immunostaining was identified in eight cases of stromal hyperthecosis, 24 adult-type granulosa cell tum ours, two juvenile granulosa cell tumours, nine Sertoli cell or Sertol i-Leydig cell tumours, one gynandroblastoma, three gonadoblastomas, tw o cases of sex cord tumour with annular tubules, two steroid cell tumo urs and two sclerosing stromal tumours. Inhibin was also present in 4/ 6 fibrothecomas and 2/3 unclassified gonadal stromal tumours. There wa s no staining of neoplastic cells in any of the problematic ovarian tu mours, in many of which a diagnosis of gonadal stromal tumour had been initially considered. However, inhibin was detected in reactive strom al cells in many cases. Conclusions: Inhibin is a sensitive immunohist ochemical marker of a wide range gonadal stromal rumours and is of val ue in differential diagnosis of ovarian neoplasia.