What causes a thyroglossal duct cyst?
A thyroglossal duct cyst is a congenital (present from birth) defect. When the thyroid gland forms during embryonic development, it begins at the base of the tongue and moves down the neck through a canal called the thyroglossal duct. This duct normally disappears once the thyroid reaches its final position in the neck. Sometimes, portions of the duct remain leaving cavities or pockets called cysts. These cysts can fill with fluid or mucus, and may enlarge if they become infected. Very enlarged cysts can cause difficulty swallowing or obstruct breathing passages.
