Coexistence of thyroid-stimulating hormone-secreting pituitary adenoma and graves' hyperthyroidism.

BACKGROUND: Coexistence of thyroid-stimulating hormone (TSH)-secreting pituitary adenoma (TSHoma) with Graves' disease has been rarely reported. We describe a female patient displaying TSHoma with Graves' disease and who presented initially with inappropriate TSH values. CASE REPORT: A 36-year-old woman presented with signs of thyrotoxicosis, small and vascular goiter and mild bilateral exophthalmos. Thyroid function tests showed hyperthyroxinemia and normal TSH values despite the use of different assays. Heterophile antibody testing result was negative. The patient underwent total right lobectomy with partial left lobectomy after 18 months of carbimazole treatment. Histology confirmed Graves' disease. Symptoms of thyrotoxicosis recurred 2 months later. Thyroid function tests showed hyperthyroxinemia and elevated TSH values. Investigations were consistent with a 10-mm TSHoma. The patient underwent a trans-sphenoidal tumor resection following preoperative lanreotide preparation. Histological examination and immunocytochemistry concluded to a pure TSH-producing tumor. There was no evidence of tumor recurrence after 18 years of follow-up.
CONCLUSION: Association of TSHoma with Graves' disease should be carefully taken into account, especially when TSH values are not compatible with either the clinical history or other thyroid functions tests.