Malignant tumors of the thyroglossal tract are rare. A review of the English literature reveals only nine reported cases of carcinoma arising in thyroglossal duct remnants. The first case was reported by Brentano3 in 1911. This occurred in a 42-year-old woman with a normal thyroid gland. A small tumor had been removed from the base of the tongue nine years before. Not all of the tumor was removed. Two years later enlarged lymph nodes were excised from the right submaxillary region. Later there were recurrences at the root of the tongue and in the right submaxillary area, and this spread into the left neck region. A large mass was removed from the left neck, and two nodules the size of small walnuts from the base of the tongue. All showed thyroid tissue.
A study of embryology explains the occurrence of the thyroid tissue in the thyroglossal tract or duct.