A case of thyroglossal duct cyst diagnosed on twenty years after the operation of congenital dermoid cyst

Thyroglossal duct cyst occuring in oral floor is extremely rere. This kind of cyst represents an embryological remnant of the descending thyroglossal duct and usually appears as an upper midline neck mass. In this report, we present a case of 20-year-old man with the cyst in the oral floor. A mass at the oral floor was first detected with suckling difficulities when he was a new born baby. The mass was removed 2 months after birth, and thn histologically diagnosed as a dermoid cyst. A cystic lesion at the same site was again diagnosed at his age of 20 years. The lesion was surgically removed. The cyst was free from the surrounding muscules and had histopathological features consistent with thyroglossal duct cyst.