An FSH and prolactin-secreting pituitary tumor: pituitary dynamics and testicular histology.

A man with normal-sizes testes and a chromophobe adenoma of the pituitary was found to have elevated plasma levels of FSH and prolactin and severe deficiencies of other trophic hormones. Plasma FSH values doubled after administration of LH-releasing hormone but were not suppressed by exogenous testosterone. Prolactin concentrations were increased by TRH and were suppressed by L-dopa. Testicular histology revealed sparse and apparently inactive Leydig cells. Seminiferous tubules and Sertoli cells were well preserved, but there were few late spermatids.