Thyroglossal Duct Cyst

Abstract

The median cervical cyst is a remnant of the thyroglossus duct, which runs from the pyramidal lobe of the thyroid gland to the foramen caecum in the dorsal part of the tongue. Embryologically, the thyroid diverticulum develops in a caudal direction from the foramen caecum after formation of the tongue. The thyroid gland descends to the neck in the same period of gestation when the hyoid bone develops from the second branchial arch. The thyroglossal duct may pass in front, behind, or through the body of the hyoid bone in the middle of the neck, and islands of thyroid tissue may be found scattered along the tract. At no time during embryogenesis does the thyroglossal duct contact the body surface; the original cysts thus never open to the skin. A fistula can only develop secondarily, such as following spontaneous perforation or surgical incision of an infected cyst.