Lingual thyroid carcinoma: a case report and review of the literature.

Ectopic thyroid tissue may reside anywhere along its embryologic path of descent. Most ectopias manifest as simple thyroglossal duct cysts in conjunction with a normally developed thyroid gland in its usual thyroid cervical bed. Lingual thyroid is a rare developmental abnormality characterized by the failure of the thyroid gland, or remnants, to descend from its embryologic site of origin at the foramen cecum to its usual pretracheal position. Carcinoma arising in a lingual thyroid is even more unusual with fewer than 30 cases reported in the literature. We report the second case of lingual papillary thyroid carcinoma and review the clinical features, natural history, diagnosis, and treatment of lingual thyroid carcinoma.