HYPERTHYROIDISM DUE TO A TSH-PRODUCING PI TUITARY-GLAND ADENOMA - A CASE-REPORT

Thyrotropin (TSH-)producing adenomas of the anterior pituitary gland a re the least frequently encountered ones and constitute a very rare ca use of hyperthyroidism. The case is presented of a 58 year old male pa tient with a well-known history of hyperthyroidism over a period of at least 9 years growing goiter. Despite different terms of medical trea tment he presented a constant clinical pattern consisting of restlessn ess and paroxysmal tachycardial atrial fibrillation. Laboratory findin gs revealed elevated levels of circulating thyroid hormones despite in adequately high levels of TSH. MRI scan revealed an adenoma of the pit uitary measuring 9 mm in diameter. After microsurgery, consisting of t ransphenoidal resection of the tumor, the patient reported no clinical symptoms. Histological examination revealed positive immunohistochemi cal staining, with antibodies to TSH, but a negative reaction against the GH, PRL, FSH, LH and ACTH hormone antibodies. Moreover, the levels of circulating hormones (GH, PRL, FSH, LH and ACTH) were normal. TSH- alpha subunits were not elevated. Before the correct diagnosis was rea ched, this patient was treated for nine years with antithyroid drugs. Five months after the operation the patient showed normal values of ci rculating thyroid hormones and TSH and thus no thyroid-specific medica tion was necessary.