Macroorchidism and panhypopituitarism: two different forms of presentation of FSH-secreting pituitary adenomas in adolescence.

BACKGROUND: FSH-secreting pituitary adenomas are extremely rare in children and are seldom associated with clinical manifestations of high serum gonadotrophin levels. Thus, most patients have a late presentation, usually as macroadenomas. CASE REPORTS: Two different clinical forms of presentation of FSH-secreting pituitary adenomas are reported: one in a 12-year-old boy with macroorchidism due to a pituitary microadenoma, probably FSH-secreting, and the other in a 15-year-old boy with panhypopituitarism due to an FSH-producing macroadenoma. Both patients presented slightly high or high FSH with low LH and high inhibin B levels. In the first case, the microadenoma was treated medically with cabergoline, which failed to reduce FSH and inhibin B levels. No radiological progression has been observed despite increasing testicular volume. In the second case, surgery was performed on the macroadenoma, leading to a decrease in FSH and inhibin B levels. The patient developed severe hypothalamic obesity and is currently under treatment with somatostatin.
CONCLUSIONS: FSH-secreting pituitary tumors have an extremely variable clinical expression. The discrepancy between normal or slightly increased FSH and low LH values, together with high inhibin B levels, strongly suggests FSH hypersecretion which should be studied.