Thyroid-stimulating hormone pituitary adenomas

Abstract

Thyroid-stimulating hormone (TSH)-secreting pituitary adenomas are rare, representing < 2% of all pituitary adenomas. The authors conducted a retrospective analysis of patients with TSH-secreting or clinically silent TSH-immunostaining pituitary tumors among all pituitary adenomas followed at their institution between 1987 and 2003. Patient records, including clinical, imaging, and pathological and surgical characteristics were reviewed. Twenty-one patients (6 women and 15 men; mean age 46 years, range 26-73 years) were identified. Of these, 10 patients had a history of clinical hyperthyroidism, of whom 7 had undergone ablative thyroid procedures (thyroid surgery/(131)I ablation) prior to the diagnosis of pituitary adenoma. Ten patients had elevated TSH preoperatively. Seven patients presented with headache, and 8 presented with visual field defects. All patients underwent imaging, of which 19 were available for imaging review. Sixteen patients had macroadenomas. Of the 21 patients, 18 underwent transsphenoidal surgery at the authors' institution, 2 patients underwent transsphenoidal surgery at another facility, and 1 was treated medically. Patients with TSH-secreting tumors were defined as in remission after surgery if they had no residual adenoma on imaging and had biochemical evidence of hypo-or euthyroidism. Patients with TSH-immunostaining tumors were considered in remission if they had no residual tumor. Of these 18 patients, 9 (50%) were in remission following surgery. Seven patients had residual tumor; 2 of these patients underwent further transsphenoidal resection, 1 underwent a craniotomy, and 4 underwent postoperative radiation therapy (2 conventional radiation therapy, 1 Gamma Knife surgery, and 1 had both types of radiation treatment). Two patients had persistently elevated TSH levels despite the lack of evidence of residual tumor. On pathological analysis and immunostaining of the surgical specimen, 17 patients had samples that stained positively for TSH, 8 for alpha-subunit, 10 for growth hormone, 7 for prolactin, 2 for adrenocorticotrophic hormone, and 1 for follicle-stimulating hormone/luteinizing hormone. Eleven patients (61%) ultimately required thyroid hormone replacement therapy, and 5 (24%) required additional pituitary hormone replacement. Of these, 2 patients required treatment for new anterior pituitary dysfunction as a complication of surgery, and 2 patients with preoperative partial anterior pituitary dysfunction developed complete panhypopituitarism. One patient had transient diabetes insipidus. The remainder had no change in pituitary function from their preoperative state. Thyroid-stimulating hormone-secreting pituitary lesions are often delayed in diagnosis, are frequently macroadenomas and plurihormonal in terms of their pathological characteristics, have a heterogeneous clinical picture, and are difficult to treat. An experienced team approach will optimize results in the management of these uncommon lesions.