Ectopic thyroid carcinoma lacking a thyroglossal duct cyst in the submental portion: a case report

Ectopic thyroid carcinomas in the submental portion arise usually from a thyroglossal duct cyst. We report a rare case of that lacking a thyroglossal duct cyst. The patient, a 32 year-old man, had two submental tumors with good mobility. CT, MRI, and US revealed two solid tumors. Fine needle aspiration cytology (FNAC) suggested thyroid papillary carcinoma metastasis. The thyroid gland itself showed normal morphology. The submental tumors were extirpated. Pathological examination revealed ectopic normal thyroid tissue and papillary carcinoma. As the edge of the extirpated tumor showed positive papillary carcinoma cells, reoperation was performed to remove the residual tumor using Sistrunk's technique. To the best of our knowledge, this is the 45th case of ectopic thyroid carcinoma with no thyroglossal duct cyst and second case of that in the submental portion in the English and Japanese literature. FNAC was the most important to diagnose and differentiate the submental tumors.