A Rare Coexistence of Thyrotropin-Secreting Pituitary Adenoma and Graves Disease

The coexistence of Graves disease (GD) and a thyroid-stimulating hormone (TSH)-secreting pituitary adenoma (TSHoma) is a rare and diagnostically challenging condition. In general, GD typically manifests with low TSH because of excess thyroid hormone production; contrastingly, a TSHoma causes secondary hyperthyroidism with normal or elevated TSH levels. This unusual overlap poses diagnostic and therapeutic challenges; therefore, a careful approach is required to distinguish and manage both conditions. We present the case of a 51-year-old woman with symptoms of hyperthyroidism, elevated thyroid hormones, low TSH, and positive anti-TSH receptor antibodies, which were suggestive of GD 10 years prior. After stopping thiamazole and levothyroxine because of the favorable control of thyroid function 6 months prior, the patient presented a syndrome of inappropriate secretion of TSH and magnetic resonance imaging revealed a pituitary macroadenoma; accordingly, she was diagnosed with concurrent GD and a TSHoma. Treatment involved transsphenoidal resection of the TSHoma and antithyroid medication to control GD. This case illustrates the rarity of coexisting GD and TSHoma and the diagnostic and therapeutic complexities of managing dual hyperthyroidism etiologies. Biochemical testing, antibody assessment, and imaging examination are essential for accurate and early diagnosis of the condition.