| Persistent thyroglossal duct | |
|---|---|
| Classification and external resources | |
| ICD-10 | Q89.2 |
| ICD-9 | 759.2 |
A persistent thyroglossal duct is a usually benign medical condition in which the thyroglossal duct, a structure usually only found during embryonic development, fails to atrophy. The duct persists as a midline structure forming an open connection between the back of the tongue and the thyroid gland.
Early during embryonic development, the thyroglossal duct is a midline structure that connects the back of the tongue to the thyroid gland. The duct usually disappears, or atrophies, during the ninth week of gestation so that in most individuals the thyroid does not connect to the tongue. In individuals with a persistent thyroglossal duct, the duct fails to atrophy, and the connection between the thyroid gland and the tongue is maintained.
A persistent thyroglossal duct may become fluid filled, forming a thyroglossal duct cyst, the most common type of congenital neck malformation. Such cysts account for approximately 2-4% of all neck masses.
Very rarely, the persistent duct can become cancerous, called thyroglossal duct carcinoma. In the case of thyroglossal duct carcinoma, the cancerous cells are ectopic thyroid tissue that has been deposited along the thyroglossal duct and usually follows exposure to radiation.
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