Cosecretion of estrogen and inhibin B by a feminizing adrenocortical adenoma: impact on gonadotropin secretion.

We describe the first reported case of a feminizing adrenocortical adenoma cosecreting estrogens and inhibin B. A 39-yr-old man, with no previous history of disease and free of treatment, complained of gynecomastia without any clinical abnormality. Plasma E2 and T were 496 pmol/liter and 8.7 nmol/liter, respectively. Testicular echography was normal, and abdominal computed tomography scan showed a 28-mm right adrenal tumor. hCG (5000 IU, im) induced a rise in plasma T levels (20.7 nmol/liter) without any change in plasma E2 levels. Basal plasma LH and FSH levels were undetectable. GnRH (100 microg, i.v.) induced an increase in plasma LH levels without a change in plasma FSH levels. The mean plasma inhibin B level was 330 +/- 45 pg/ml (normal range, 94-327). Pulsatile GnRH administration (20 microg/pulse every 90 min for 3 d) stimulated LH secretion, whereas FSH secretion remained blunted. The patient underwent surgery to remove a 12-g adrenal adenoma. Six months later, plasma E2 and T levels were normalized. LH showed a spontaneous pulsatile pattern, and the mean plasma FSH level was 4.8 U/liter. The secretion of both gonadotropins was stimulated during a pulsatile GnRH administration performed in the same manner as before surgery. The mean plasma inhibin B level was 210 +/- 25 pg/ml. Immunohistochemical studies revealed the presence of aromatase in clusters of tumor cells. Incubation of tumor sections with anti-beta(B)-inhibin antibody revealed intense staining in groups of cells that were also labeled with anti-alpha-inhibin antibody. These data show that the tumor cosecreted E2 and inhibin B, which were both responsible for inhibition of gonadotropin secretion. Tumor secretions appeared to be much more potent in suppressing FSH than LH levels.