THE SITE OF INHIBIN PRODUCTION IN OVARIAN NEOPLASMS

Inhibin, a physiological product of ovarian follicle cells, normally a bsent in serum of postmenopausal women, is elevated in adult granulosa cell tumours of the ovary, Recently, high serum levels of inhibin wer e reported in carcinomas and, surprisingly, also in Krukenberg tumours of the ovary, This study attempted to determine the site of inhibin p roduction in primary (111 cases), metastatic (13) and secondary (10) o varian tumours by using immunohistochemistry. Positive staining in tum our cells was encountered in all cases of sex-cord- stromal cell rumou rs, adult (13) and juvenile (3) granulosa cell tumours, thecofibromas (10), in a lipid cell tumour (1) and a Sertoli-Leydig cell tumour (1). Primary and secondary tumours not derived from sex-cord stroma reveal ed no positivity in tumour cells, but in theca-like cells in the surro unding non-neoplastic ovarian stroma, A positive reaction was not obse rved in non-tumour-bearing ovaries of a control group. The ovarian inh ibin of postmenopausal women is derived from activated sex-cord stroma or sex-cord-stromal neoplasms. Therefore, elevated serum inhibin conc entrations in women with primary or secondary ovarian neoplasms with o ther histogenesis seem to be due to an activation of the non-neoplasti c ovarian stroma, Inhibin will fail to be a tumour marker in these cas es. By contrast, it will be useful in proving sex-cord differentiation by immunohistochemistry and might be used in surveillance of malignan t sex-cord derived neoplasms by serum assays.