Production of immunoreactive inhibin by a virilizing ovarian tumour (Sertoli-Leydig tumour).

A 59-year-old post-menopausal woman was admitted to the hospital with atypical vaginal bleeding and hirsute lower extremities. There was a high serum testosterone level (15.8 nmol/l) and also an appreciable serum immunoreactive inhibin level. No adrenal or ovarian lesions were detected by conventional imaging procedures. Selective blood sampling was performed during venous catheterization and showed that testosterone and inhibin levels were highest in the right ovarian vein. Laparotomy revealed a Sertoli-Leydig tumour in the right ovary, which was excised. Post-operatively, immunoreactive inhibin became undetectable while the testosterone level fell to 2.8 nmol/l. Specific radioimmunoassay showed a high immunoreactive inhibin content in the tumour. These findings indicate that Sertoli-Leydig tumours can produce both testosterone and immunoreactive inhibin, both of which would then inhibit LH and FSH release to produce the symptoms seen in this patient. Thus, assay of inhibin may aid in the differential diagnosis of virilizing tumours.