Papillary thyroid carcinoma of the thyroglossal duct cyst: comparative cytohistologic and immunochemical study of 2 new cases and review of the literature.

We report a cytohistologic and immunohistochemical study of 2 cases of papillary thyroid carcinoma occurring in a thyroglossal duct cyst. The patients were a 21-year-old woman and a 48-year-old man. Needle aspiration cytology smears were consistent with papillary thyroid carcinoma. The Sistrunk procedure was done. Papillary carcinoma was found within a thyroglossal duct cyst. In 1 case, the tumor spread outside the cyst. Follow-up was uneventful in both patients (2 and 9 years, respectively). Our results would indicate that papillary carcinoma of thyroglossal duct cyst, though indistinguishable from its thyroid homologue, has a more indolent course and could therefore be singled out as a clinicopathologic entity. Needle aspiration cytology reliably assists in planning patient management.