Abstract
This article reports an older woman with a 2-year history of enlarging submental neck mass. Head and neck imaging displayed a group with a solid central component. Additionally, a fine-needle aspiration suggested neoplasia. Thyroglossal duct cyst cancer is sporadic, accounting for ˂1% of all thyroid malignancies. A Sistrunk procedure was followed by a total thyroidectomy and unilateral neck dissections. From histological and immunohistochemical examinations, the incidental finding of carcinoma indicates the diagnosis of thyroid tissue thyroglossal duct cyst carcinoma, as it is the most common site for malignancy in ectopic thyroid tissue. The patient had an excellent recovery without additional treatments after surgery.