Graves' disease triggered by autoinfarction of an autonomously functioning thyroid adenoma.

A patient whose nontoxic autonomously functioning thyroid adenoma had been stable for at least 3 yr developed enlargement of the nodule and hyperthyroidism. It was assumed the hyperthyroidism was caused by evolving toxicity in the autonomous adenoma, but imaging showed the nodule had undergone infarction and the hyperthyroidism was secondary to Graves' disease. This case demonstrates the necessity of thyroid imaging in patients with nontoxic autonomously functioning thyroid adenomas when there is a change in nodule size or thyroid function which requires treatment.