Lingual thyroid occurs due to the lack of normal caudal migration of the thyroid gland from the foramen cecum down to its normal location anterior to the larynx and upper trachea. Lingual thyroid represents 90% of ectopic thyroid glands, the majority of these show absent thyroid tissue in the normal anatomical location.

It follows all imaging criteria of the normal thyroid gland and is susceptible to all known thyroid pathologies, being symptomatic due to its mass effect when it enlarges as in multinodular goiter. Also, about one-third of patients develop hypothyroidism.