Thyrotoxicosis due to ectopic lateral thyroid tissue presenting 5 years after total thyroidectomy.

Objective: To describe a patient who, 5 years after total thyroidectomy to treat Graves disease, presented with thyrotoxicosis due to nonmalignant lateral ectopic thyroid tissue.

Methods: We describe the laboratory, imaging, and physical findings of the study patient and review the relevant literature.

Results: A 32-year-old white woman with a history of Graves disease presented with recurrent hyperthyroidism 5 years after total thyroidectomy. A radioactive iodine scan was performed, which revealed elevated uptake (40%) and positive imaging in the left mid-neck. Ultrasonography examination of the neck confirmed the absence of any thyroid tissue within the thyroid bed, but documented 2 nodular, hypoechoic left upper-neck masses with punctuate hyperlucency. Contrast-enhanced computed tomography was performed to precisely localize the nodules, which were excised surgically via selective neck dissection. Histopathologic examination revealed chronic lymphocytic inflammatory infiltrate with focal thyroid hyperplasia and papillary infoldings and no evidence of malignancy.

Conclusions: To our knowledge, this represents the first report of ectopic benign thyroid tissue as the sole cause of hyperthyroid symptoms, and this entity should be considered in patients who have undergone thyroidectomy and have persistent hyperthyroidism.