MONOCLONAL-ANTIBODIES AGAINST INHIBIN REPRESENT KEY MARKERS OF ADULT GRANULOSA-CELL TUMORS OF THE OVARY EVEN IN THEIR METASTASES - A REPORTOF 3 CASES WITH LATE METASTASIS, BEING PREVIOUSLY MISINTERPRETED AS HEMANGIOPERICYTOMA

Antibodies against human inhibin, a peptide hormone produced by ovaria n granulosa cells to inhibit FSH, are widely applied to determine seru m inhibin levels. Recently, they were, however, proved also to stain f ollicle cells in ovarian tissue by immunoreactions in histological sec tions. The commercially available inhibin antibody produced by Serotec , applied to sections of paraffin blocks, stained follicle epithelia i n 6/6 samples of ovarian tissue from females under the age of 40 recru ited from the archives, Adult granulosa cell tumor tissue samples from primary tumors of the ovary showed positive reaction in 6/6 cases, No positive reaction was found in staining tissues from hemangiopericyto mas from males (0/3), leiomyomas, leiomyosarcomas, and a malignant mel anoma (0/5), serving as negative controls. No positive reactions could be observed in tumor cells of 10 ovarian carcinomas, whereas in two o f these cases single cells of the specialized ovarian stroma stained p ositively with inhibin. Positive immunostainings were revealed in thre e late metastases (two within the liver) from granulosa cell tumors in females, primarily misinterpreted as hemangiopericytomas or leiomyosa rcomas, because the previously resected primaries of the ovary were no t known at the time of liver surgery. The recognition of granulosa cel l tumors, especially the distinction of the sarcomatoid growth type fr om soft tissue tumors, may be difficult, even if immunostaining for in termediate filaments are applied, Immunostaining by antibodies against inhibin, which can be applied reliably in histopathology, may therefo re provide a useful tool to distinguish between granulosa cell tumors and genuine soft tissue tumors. This is also of clinical importance, b ecause treatment of the former by cisplatin-based polychemotherapy and antisex hormone therapy proved to be helpful, Furthermore, the inhibi n antibody can be used as an early serum marker for detecting tumor re currence months before clinical evidence.