Aggressive form of thyroglossal duct cyst carcinoma: role of ablative dose of Iodine-131

Ectopic thyroid tissue carcinoma is very rare and has usually good prognosis. It could arise in 1 percent of thyroglossal duct cysts (TDC), the most common nonodontogenic cysts that occur in the neck, which results from a failure in obliterating the embryogenic duct produced during thyroid migration. TDC is most often diagnosed during the childhood but may be discovered later in adult age. In most of the cases reported in the literature, thyroid carcinoma arising in the TDC is limited to the cyst without local extension and its efficient treatment consist of the surgical removal of the cyst by Sistrunk's operation. However, some controversies remain regarding the indication of total thyroidectomy when thyroid investigations are normal. Cases of aggressive thyroid carcinomas of the TCD with metastatic cervical lymph nodes are exceptional, mainly when histological findings of the thyroid gland are normal. We report a case of an aggressive form of a thyroglossal duct cyst carcinoma complicated with several infiltrated cervical lymph nodes but normal thyroid gland. The therapeutic strategy adopted in this case shows the decisive role of the post-operative ablative dose of Iodine-131 both for treatment and staging of aggressive form of thyroid carcinoma arising in thyroglossal duct cyst.