Ectopic thyroid tissue.

Abnormalities in the embryologic development and migration of the thyroid gland can result in ectopic thyroid tissue, which may occur on the midline in any position from the base of the tongue to the mediastinum. Although ectopic thyroid tissue may be asymptomatic, local obstructive, hemorrhagic or other complications may occur. Radionuclide thyroid scan is confirmatory when the diagnosis is suspected. Hypothyroidism is common in lingual thyroid, and thyroid supplementation is generally required.