Follicle-stimulating hormone-secreting pituitary tumor with concomitant elevation of serum alpha-subunit levels.

Hypersecretion of FSH and alpha-subunit was documented in a man with a pituitary adenoma that was previously diagnosed on clinical grounds as nonfunctioning who had been treated by transsphenoidal surgery and postoperative irradiation. Postoperatively, the patient had high serum FSH levels and normal serum, LH levels. Ten years after the surgery, immunostaining of the tumor revealed the presence of beta FSH, beta LH, and beta TSH in the cytoplasm of scattered adenoma cells, although not always in the same cells. LH levels were elevated during the middle portion of the 12 yr that this patient was followed. However, as LH immunoreactivity was shown (in specimens recently drawn) to be largely due to cross-reactivity in the alpha-subunit RIA, the high LH values may represent high alpha-subunit levels. The elevated FSH levels and alpha-subunit concentrations did not rise after GnRH administration. Thus, during the course of 12 yr, this patient's tumor hypersecreted FSH and alpha-subunit and possibly LH. The evolution of these events may represent the natural history of the tumor or the effects of the therapeutic modalities used. We conclude that adult men with pituitary tumors and complaints of hypogonadism should be evaluated for a FSH-secreting tumor.