BACKGROUND In 1 % of the thyroglossal duct cysts malignant transformation is found with predomination of the papillary carcinoma (80 %). CASE REPORT We present the case of a 51 year old man with a synchronic papillary carcinoma in a thyroglossal duct remnant and a microcarcinoma of the thyroid gland. After exstirpation of a thyroglossal duct cyst histological examination identified a papillary carcinoma. Postoperative staging uncovered enlarged lymph nodes but no abnormalities in the thyroid gland. Cervical lymphadenectomy and total thyroidectomie was performed. On histological examination a synchronic microcarcinoma of the thyroid was shown. CONCLUSION Only 7 similar cases have been published in literature before. Because of the rare incidence no therapeutic standard could be established so far. We discuss our therapeutic approach as well as the relevant literature.