A thyroglossal duct cyst is a congenital developmental abnormality formed by the incomplete closure of the thyroglossal duct during embryonic life, with some or all of it remaining in the middle of the neck, and a fistula is formed when the cyst ruptures. The thyroglossal duct cyst usually appears around 1 year of age and is often located in the midline of the neck and below the anterior hyoid bone, so it is caused by a congenital abnormality, and although the symptoms appear late, it is still congenitally not well closed and not completely degenerated. Therefore, when a thyroglossal cyst is found, surgery is recommended at about 2 years of age, usually to remove part of the hyoid bone and the blind hole at the root above the hyoid bone, so as to avoid recurrence.