Ectopic lingual thyroid: an entity not to be missed!

Thyroid gland develops from endodermal tissue of foramen cecum at anterior 2/3rd and posterior 1/3rd of tongue between 3rd4th week of gestation, penetrate downward to reach its normal adult location at 2nd4th tracheal rings in the neck during 7th week of gestation.1,2 Ectopic lingual thyroid is a rare congenital entity with prevalence of 1 in 1-3 lakh population.3 It occurs due to arrest of migration of endodermal tissue from foramen caecum to its final pre-laryngeal location in the beginning of its development. Aberrant migration can lead to presence of ectopic thyroid tissue at any of the locations in its natural course. Many a times there is no migration of thyroid tissue from foramen cecum resulting in lingual thyroid. Ectopic thyroid tissue can be found at any location in its normal migratory pathway, however has also been found in mediastinum, esophagus, adrenal gland and heart.4–7 Most common (90%) form of ectopic thyroid is lingual thyroid.3 In such cases there is no thyroid tissue in the body elsewhere, therefore surgical excision must be avoided as this is the only functioning thyroid tissue left in the body.