Thyroglossal duct cyst is a rare lesion, and originates from the remaining epithelium of the thyroglossal duct. W e report a case of the thyroglossal duct cyst and discuss its relation to the hyoid bone.
A 13-year-old boy was referred to us because of a tumor at the submental region on April 19, 1989. An elastic hard mass with a slight mobility, about 40×40×30mm, was palpated at the region. Computed tomography revealed a cystic lesion adhering to the hyoid bone. A diagnosis of thyroglossal duct cyst was made, and extirpated with a fistula to the cecal foramen under general anesthesia on July 27, 1989. The hyoid was partially removed with the cyst because of a persistent adhesion. The cyst, 35×40×25mm, showed a multilocular appearance, and the content had a jelly-like viscosity with a foul odor. Histopathology revealed that the cyst was lined with stratified squamous epithelium, which was partially replaced by granulation tissue. Many small cystic lumens lined by ciliated columunar epithelium were noted on the periphery to the fistula. Many mucous glands were also seen adjacent to the microcysts.
High incidence of the cyst is noted in the subhyoid contrary to the low incidence in the suprahyoid region. Accessory thyroid glands often associate with the subhyoid type despite almost concomitant mucous glands in the suprahyoid type. We accordingly speculated a close relationship between the cyst and hyoid, because the invaginating route of the thyroglossal duct is thought to be distorted by the appearance of the anlage and subsequent rotation of the hyoid.
