Diagnosis and treatment of TSH-secreting adenomas: review of a longtime experience in a reference center.

Abstract

TSH-secreting pituitary adenomas are among the less prevalent pituitary tumors, corresponding to 0.9-1.5% of all pituitary adenomas in surgical series. A series of 11 patients with TSH-secreting and cosecreting adenomas diagnosed and treated in the last 25years in a single center is described. The mean age at diagnosis was 37 years (range 18-80years; median 23years); the ratio of male-to-female patients was similar (6M:5F). Only three patients was the correct diagnosis established shortly after the initial medical evaluation. Other four patients were initially diagnosed with other pituitary adenomas (prolactinoma, acromegaly, and non-secreting pituitary tumor) and another four diagnosed with primary hyperthyroidism. There was a mean diagnostic delay of 6.0years (range 0.5-25years; median 2years). Nine patients had macroadenomas and two patients had microadenomas. Seven patients underwent pituitary surgery which controlled the disease in only two (one micro- and one noninvasive macroadenoma). The other treatments were directed to the thyroid gland (surgery or 131I radiotherapy), pituitary radiotherapy, and somatostatin analog. In spite of its relatively straightforward diagnosis, which includes clinical/subclinical hyperthyroidism with or without goiter, increased free thyroxine and nonsuppressed TSH levels, and pituitary mass, the diagnosis of TSH-secreting and cosecreting adenomas was frequently unrecognized and thus much delayed. Serum alpha-subunit levels were high in nearly all patients with TSH-secreting adenomas and useful in excluding other conditions in the differential diagnosis. Proper indication and interpretation of simple laboratory tests should be emphasized in medical education to improve diagnostic accuracy.