[Papillary thyroid carcinoma in a thyroglossal duct cyst: primary tumor or metastasis?].

Thyroglossal duct cysts are the most common anomaly in thyroid development. The occurrence of carcinoma in a cyst is reported to be about 1% of cases. Histopathological examinations reveal a papillary thyroid carcinoma in about 94% of these. We report the case of 38-year-old female having a massive, cervical cystic mass over a period of 18 months. An ectopic papillary thyroid carcinoma was diagnosed. A total thyoidectomy and bilateral neck dissection were performed. This revealed a small thyroid carcinoma and three positive lymphatic nodes. Whether the cystic carcinoma is the primary or a metastasis of the thyroid carcinomais discussed.