A case of TSH-secreting pituitary adenoma with acromegaly

Growth hormone (GH) and thyrotropin (TSH)-secreting pituitary adenomas are very rare and account for only 0.5% of all pituitary adenomas. We report a case of a GH/TSH-secreting pituitary adenoma in a 53-year-old male patient. He presented with symptoms of thyrotoxicosis, clinical features of acromegaly, and diabetes mellitus. The laboratory examinations showed high serum levels of free T4, TSH, and free alpha-subunit. Additionally, serum levels of GH and insulin-like growth factor (IGF-1) were increased. GH was not suppressed below 1 μg/L by an oral 75 g glucose loading test, and TSH was not stimulated by thyrotropin-releasing hormone. A sellar MRI showed a large lobulated mass on the pituitary gland, so transcranial surgery was performed. Immunohistochemical staining showed anti-GH and anti-TSH positive tumor cells in the cytoplasm. Serum GH, IGF-1, free T4, and TSH levels normalized after surgery.