Diagnostic Value of Inhibin Immunoreactivity in Ovarian Gonadal Stromal Tumours and Their Histological Mimics

Aims: Inhibin is a heterodimeric protein hormone which appears to be a sensitive serological and immunohistochemical marker of ovarian granulosa cell tumours. The purposes of this study were to examine inhibin immunoreactivity in a wide range of gonadal stromal neoplasms and to assess its value in the differential diagnosis of problematic ovarian tumours.

Methods And Results: Inhibin immunostaining was identified in eight cases of stromal hyperthecosis, 24 adult-type granulosa cell tumours, two juvenile granulosa cell tumours, nine Sertoli cell or Sertoli-Leydig cell tumours, one gynandroblastoma, three gonadoblastomas, two cases of sex cord tumour with annular tubules, two steroid cell tumours and two sclerosing stromal tumours. Inhibin was also present in 4/6 fibrothecomas and 2/3 unclassified gonadal stromal tumours. There was no staining of neoplastic cells in any of the problematic ovarian tumours, in many of which a diagnosis of gonadal stromal tumour had been initially considered. However, inhibin was detected in reactive stromal cells in many cases.

Conclusions: Inhibin is a sensitive immunohistochemical marker of a wide range of gonadal stromal tumours and is of value in the differential diagnosis of ovarian neoplasia.