Anatomical reconstruction of the thyroglossal duct.

The high postoperative recurrence rate of the thyroglossal duct cyst is well known. Since Sistrunk's operation was used, the recurrence rate was remarkably reduced, but the anatomical description of the thyroglossal duct through the entire tract has not been clarified in detail. For a more accurate anatomical understanding of the thyroglossal duct, 10 specimens obtained from Sistrunk's operation were studied using histological reconstruction, and a common running pattern of the thyroglossal duct was found. The cyst is usually located caudal to the hyoid bone mostly at the midline. The duct extends upward from the cyst ventral to the hyoid bone, with many or a few branches and secretory glands. These ducts or branches merge into a single duct at the level of the cranial portion of the hyoid bone. However, as it leaves the hyoid bone and approaches the foramen cecum, a single duct spreads out into many ductuli like the tip of a broom, which communicate with many secretory glands. There were three cases in which the duct was found behind the hyoid bone, but in no case did the thyroglossal duct run through the back of the hyoid bone. The duct behind the hyoid bone was recognized as a branch from the main duct in the dorsal direction. It ascended to the dorsal surface of the hyoid bone and terminated blind. These findings emphasized the importance of Sistrunk's operation to prevent a recurrence.