Thyroglossal cyst (thyroglossal cyst) refers to the congenital cysts formed in the neck left behind by the incomplete degeneration of the thyroglossal duct in the process of thyroid development in the early embryonic period and its non-disappearance. Cysts often have epithelial secretions accumulated within the cyst, the cyst can be communicated with the oral cavity through the tongue blind hole, and secondary infection cysts can rupture to form a thyroglossal fistula. Thyroglossal cysts are the most common congenital neck mass, accounting for 40% of primary neck masses and 70% of causes of congenital neck pain. Etiology The normal thyroglossal duct is located in front of the hyoid bone, with a diameter of 1 to 2 mm, and is closely connected to the front of the hyoid bone and cannot be separated. Its occurrence began in the fourth week of the embryo, in the primitive pharyngeal floor wall in the midline equivalent to the plane of the second and third pairs of gill arches, epithelial cell hyperplasia, the formation of a caudal extension of the blind tube that is the thyroid primordial, called the thyroglossal duct. The thyroglossal duct descends along the midline of the neck to the anterior aspect of the future trachea, where the end expands laterally to form the right and left lateral lobes of the thyroid gland. Under normal conditions, the thyroglossal ducts begin to atrophy and degenerate by the sixth week of the embryo. After the degeneration of the upper segment of the thyroglossal duct disappears, a shallow depression remains at the opening of its beginning segment, called the blind foramen. If for some reason the thyroglossal duct does not disappear or degenerates incompletely after the 10th week, the remaining tubular structure partially due to the accumulation of epithelial secretions, can form a cyst in the front of the neck in the middle of the tongue root to the thyroid gland within the trip, is the thyroglossal duct cysts, can be infected and form a fistula, is the thyroglossal fistula. There are three types of fistulas: complete fistulas, from the blind hole to the skin of the neck; endoblastic fistulas, which open into the blind hole; and exoblastic fistulas, which open into the skin of the neck. Prevalent age and site Thyroglossal cysts are predominantly male, occurring in children and adolescents, about 50% of cases occurring before the age of 20 years, the vast majority of patients can be seen in the anterior cervical swelling, which can occur in the cervical midline from the blind hole of the tongue to the sternal incision of any part of the intersection between the hyoid bone, but the hyoid bone in the upper and lower parts of the most common, and sometimes can be skewed to one side. Clinical manifestations: The cyst is slow-growing and rounded, and may be accompanied by local symptoms such as neck distension, discomfort in swallowing, and foreign body sensation in the pharynx. If the cyst is located in the vicinity of the tongue blind hole, it can elevate the root of the tongue and cause swallowing, speech and respiratory dysfunction. Combined infection can be manifested as a painful mass or abscess, and if a fistula has been formed, a sinus tract can be seen, with mucus or purulent secretion flowing out of the sinus tract. Those with significant infection may be accompanied by systemic symptoms such as fever and fatigue.