Ectopic thyroid tissue can be found anywhere between the foramen cecum and the normal position of the thyroid gland, most commonly located in the anterior cervical area, the region of the thyroglossal duct. Although thyroid cancer has been described frequently in thyroglossal duct remnants, thyroid dysfunction related to this tissue is rare. We report a patient with recurrent Graves' disease arising in a thyroglossal duct remnant.A 40-year-old woman with a history of total thyroidectomy for Graves' disease, presented with a slowly enlarging midline neck mass in association with clinical signs of hyperthyroidism. Serum-free triiodothyronine (6.6 pg/mL) and serum-free thyroxine (2.2 ng/dL) were elevated (normal range, 2.3-4.2 pg/mL and 0.9-1.8 ng/dL, respectively), and thyroid-stimulating hormone was suppressed (0.01 mIU/mL; normal range, 0.35-5.50 mIU/mL). Neck ultrasonography showed a solid mass, localized at the infrahyoid area; radionuclide scanning confirmed an increased uptake at the same level. A 4 cm solid mass was removed by the Sistrunk technique. Microscopic examination revealed marked follicular hyperplasia, with tall cells, small follicles, scant, and scalloped colloid, in association with patchy lymphocytic infiltrate consistent with Graves' disease.There appears to be no reason why thyroid cells within thyroglossal duct remnants should not be influenced by the thyroid-stimulating immunoglobulins of Graves' disease. Thyrotoxicosis resulting from this must be very rare, however, as were unable to find reports of patients with thyrotoxicosis due to Graves' disease in thyroglossal duct remnants. Although some thyroid tissue can be found within the thyroglossal duct in 1.6% to 40% of normal adults, the risk of thyroid dysfunction from this is far too low to justify new therapeutic approaches.
