A 27 year-old healthy woman was seen with a midline swelling in the neck. On physical examination this was consistent with a thyroglossal duct cyst. Histological examination following surgical excision revealed a papillary carcinoma arising in a thyroglossal duct cyst.

Primary carcinomas of thyroglossal duct tissue are rare, and usually diagnosed after surgery. In this paper we report the case of papillary carcinoma arising in a thyroglossal cyst which was diagnosed as benign thyroglossal cyst before the operation and the literature was reviewed.