Background: Persistent thyroglossal duct leads to a fibrous cyst formation named thyroglossal cyst which is the most common form of congenital cyst and usually located in the midline neck below the hyoid bone. Rarely the thyroglossal cyst is associated with thyroid cancer. Although the Sistrunk procedure is often considered adequate, currently there is no clear consensus on the optimal management of thyroglossal duct cyst especially duct cyst carcinoma. In addition, there is no consensus about concurrent thyroidectomy in patients with thyroglossal cyst duct carcinoma.
Case presentation: In this article, we present four patients with thyroglossal duct cyst and papillary thyroid cancer. Papillary thyroid cancer was located into the thyroglossal duct cyst (thyroglossal duct carcinoma) in two patients and two patients had thyroglossal duct cyst with thyroid carcinoma in thyroid tissue. Cervical lymph nodes were involved in one of the three patients. Sistrunk procedure and total thyroidectomy were performed for all. The thyroid lobes were not involved in patients with thyroid duct cyst carcinoma.  Tumor or thyroglossal duct cyst recurrence did not occur in any of the patients in follow-up.
Conclusion: The correlation between thyroglossal cyst and papillary thyroid carcinoma is high. In subjects with thyroglossal duct cyst, in addition to cyst assessment, thyroid gland and neck lymph nodes should be evaluated for malignancy.