A Silent Follicle-Stimulating Hormone-Producing Pituitary Adenoma in a Teenage Male

An 18-year-old male was referred to Toranomon Hospital seeking reoperation for recurrent clinically nonfunctioning pituitary adenoma. A pituitary macroadenoma was first suspected at age 15 due to intractable headaches. Endocrine data were unremarkable except slightly elevated serum follicle-stimulating hormone (FSH). Transsphenoidal surgery done at another hospital achieved partial tumor removal but the remaining tumor regrew 2 years after surgery. The recurrent tumor was completely and selectively removed on repeat surgery at Toranomon Hospital. Pathological examination confirmed a silent FSH-producing pituitary adenoma. Forty-five patients less than 20 years old underwent transsphenoidal surgery for pituitary adenoma at Toranomon Hospital between 1993 and 2010. Of the 45 patients, 36 (80.0%) had clinically functioning adenomas and the other 9 (20.0%) had clinically non-functioning adenomas. No patients, other than the present case, had a silent gonadotroph adenoma. In contrast, among 579 patients over 20 years old undergoing surgery for nonfunctioning pituitary adenomas between 2006 and 2010 at Toranomon Hospital, 304 (52.3%) had silent gonadotroph adenomas. Gonadotroph adenomas are more common with aging: for example, 37 (61.7%) of 60 patients more than 70 years old at the time of operation had gonadotroph adenomas. In conclusion, gonadotroph adenomas, especially silent gonadotroph adenomas, are extremely rare in childhood and adolescence.