Abstract
Ectopic thyroid tissue is an uncommon embryologic aberration characterized by the presence of thyroid tissue in a site other than its usual pre-tracheal location. Single ectopic thyroid tissue is the most common variant, and the base of the tongue is the most frequent ectopic location. Dual ectopic thyroid is extremely rare, and only eleven cases have been reported in the English literature. Furthermore, adenomatous hyperplasia has never been reported to arise from dual ectopic thyroid. There has been only one reported case of adenomatous hyperplasia arising from a single intratracheal ectopic thyroid. We report a case of adenomatous hyperplasia arising from dual ectopic thyroid tissue that presented as a sublingual mass in a 37-yr-old woman. The diagnosis was made through pathologic examination after surgical resection. We also discuss the diagnosis and treatment of ectopic thyroid, along with a review of the literature.