Gonadotroph adenoma with secondary hypersecretion of testosterone

Gonadotroph pituitary adenomas are common, but the overwhelming majority are classified as nonfunctioning adenomas. Approximately one-third secrete follicle-stimulating hormone (FSH) and/or luteinizing hormone (LH), resulting in an increase in serum levels; however, the sex hormone levels are typically not elevated and the secreted gonadotropin hormones are thought to be biologically inactive. Rarely, gonadotroph adenomas induce an ovarian hyperstimulation syndrome in females. In males, an increase in the testosterone level is even rarer. The authors report the case of a male patient with a gonadotroph pituitary adenoma causing hypersecretion of testosterone and review the medical literature.

A 45-year-old man had progressive bilateral visual loss over a 4-year period. Bitemporal hemianopsia was diagnosed by an ophthalmologist, but no other symptoms were reported. Neurosurgical evaluation was otherwise normal. Magnetic resonance imaging of the brain showed a large enhancing sellar and suprasellar tumor consistent with pituitary macroadenoma. Levels of FSH, LH, α-subunit, testosterone, free testosterone, and prolactin were elevated. The patient underwent transsphenoidal resection of the pituitary tumor. Pathologic analysis confirmed the diagnosis of pituitary adenoma, and immunohistochemistry demonstrated a population of cells with cytoplasmic staining for FSH but not for LH. The postoperative hormonal profile showed normalization of FSH and low LH, testosterone, morning cortisol level, and free thyroxine. The patient was treated with levothyroxine and hydrocortisone therapy for replacement. His vision subjectively improved at a formal visual testing follow-up to monitor the degree of improvement.

Gonadotroph adenomas are considered a type of nonfunctioning pituitary tumors, because the commonly associated increase in serum FSH and LH does not typically result in elevated sex hormone levels. Herein, we report a rare case of high testosterone level caused by a gonadotroph adenoma successfully treated with transsphenoidal resection. Interestingly, in adult males, the increase in sex hormones does not seem to lead to a recognizable clinical syndrome, and the clinical presentation remains similar to that of nonfunctioning adenomas.