Lingual and hyoid thyroid

Abstract

A LINGUAL thyroid gland is an ectopic thyroid. NormaIIy, the thyroid gIand originates from a descent of the epitheIia1 covering of the primitive digestive tract in the region of the foramen cecum at the base of the tongue, and also of islands of cells growing from the fifth lateral pharyngeal pouch [I]. However, this branchia1 tissue soon undergoes atrophy and participates in no way in the deveIopment of the adult gIand. The line of migration of the thyroid from the foramen cecum to its normal position in the neck is marked by a fibrous tract: the thyroglossal tract. Any failure of descent of the thyroid gland or of any islands of epithehal cells resuhs in tota or partia1 ectopic anomalies [2,3]. These ectopias are either IinguaI or hyoid thyroids or thyrogtossal cysts or sinuses. In total ectopia, no thyroid tissue is found in the neck in its usual site; only the arteries and parathyroid glands can be seen at exploration. Lingual thyroids are not frequent, and this very infrequency has prevented the study of any large series of cases. At I’HbteI-Dieu de Quebec Hospital from January 1946 to January 196% 1,875 cases of thyroid disease were recorded, of which there were seventy-five cases of thyroglossa1 cysts or sinuses and Ii\-e cases of ectopic thyroids. (TabIe I.)