A thyroglossal fistula is caused by a thyroglossal duct cyst. A thyroglossal duct cyst is a congenital cyst left in the neck as a result of incomplete degeneration of the thyroglossal duct during early embryonic thyroid development, which does not completely disappear. A thyroglossal duct cyst has no significant impact on life, but once a thyroglossal duct fistula develops, it is more dangerous and can lead to an acute suppurative infection of the thyroid gland secondary to systemic infection, fever, severe thyroid pain, and abnormal thyroid function. The risk of thyroglossal fistula can also be manifested in the fistula of the neck, where mucus or purulent mucus repeatedly appears, seriously affecting the patient’s quality of life and requiring surgical excision of the thyroglossal fistula.