Diagnosis and treatment of thyroglossal duct cyst (fistula): Thyroglossal duct cyst is a congenital developmental disease and one of the common diseases in oral and maxillofacial surgery. During the development of the thyroid gland in early fetal embryo, the thyroglossal duct should disappear on its own by the 6th week of embryonic development. If the thyroglossal duct does not disappear and remains in the neck, the residual epithelial secretions in its duct accumulate thus forming a congenital thyroglossal duct cyst. Because the cyst can be connected to the oral cavity through the blind lingual foramen, a thyroglossal fistula can be formed (in the oral cavity) or a thyroglossal fistula can be formed in the neck (in the neck) due to secondary infection. Thyroglossal cysts are most often seen in children aged 1 to 10 years, but can also be seen in adults. Cysts occur in the midline of the neck, anywhere between the blind foramen and the sternal notch, but the upper and lower part of the hyoid bone is the most common, and the cysts that occur on the hyoid bone are usually called “thyroglossal cysts”. The thyroglossal cyst is slow-growing, round, usually located in the middle of the neck, sometimes slightly to one side, soft, clear circumference, no adhesion with the surface skin and surrounding tissues, if the cyst is located under the hyoid bone, the cyst can move up and down with swallowing and tongue extension. The diagnosis of thyroglossal cyst can be made generally according to the location of onset and movement with swallowing, sometimes puncture, ultrasound and imaging are feasible. A thyroglossal cyst (fistula) can only be treated surgically, and a thyroglossal fistula may become cancerous if left untreated for a long time, so the bottom of the surgery must be cut to prevent recurrence. The key points of surgical treatment for thyroglossal cyst (fistula) to prevent recurrence are the following three: (1) complete removal of the cyst or fistula; (2) complete removal of the middle part of the hyoid bone where the cyst or fistula is attached (adhesions); (3) removal of the adjacent muscle in the direction of the hyoid bone up to the blind foramen of the tongue. The above surgical points should be mastered in order to avoid recurrence after surgery to the greatest extent possible.