An autonomously functioning thyroid carcinoma associated with euthyroid Graves' disease.

A 39-yr-old man with an autonomously functioning thyroid carcinoma is presented. Only 17 similar cases have been reported in the literature. The patient had unilateral Graves' ophthalmopathy. He was euthyroid as reflected by normal TSH concentration, whereas the results of a T3 suppression test established the presence of autonomous thyroid function. A thyroid scan with (123)I revealed a hot nodule corresponding to the location of a papillary carcinoma and remained substantially unchanged after T3 administration. The hyperfunction of the carcinoma itself was clearly confirmed by the intense concentration of (131)I within the tumor on microautoradiograms. While a hot nodule on radioiodine scan is unlikely to be malignant, the possibility of carcinoma should not be overlooked.