Background. We present two rare cases of papillary carcinomas which appeared in thyroglossal duct cysts. These cases highlight that thyroglossal duct cyst can serve as malignancy of thyroid gland. Methods. A retrospective case report was carried out on 2 patients at Cipto Mangunkusumo Hospital. Results. A 57-year-old man presented with enlarged right anterior and midline neck mass, which preoperatively were diagnosed as thyroglossal duct cyst (TDC) and nontoxic multinodular goiter. A total thyroidectomy and Sistrunk procedure were performed. In the second case, a 35-year-old woman presented with a lump which occurred at anterior neck region without palpable mass at the thyroid. Preoperatively, it was diagnosed as TDC. Sistrunk procedure was performed, followed by total thyroidectomy a month after the first operation. Histopathology showed papillary thyroid carcinoma in both patients. Conclusion. The occurrence of carcinoma in TDC is very rare but should always be considered as an option in making diagnosis for a neck mass.