Papillary Thyroid Carcinoma Arising From a Thyroglossal Duct Cyst: A Case Report.

The thyroglossal duct is an epithelial tract that connects the foramen cecum to the thyroid gland and typically regresses during embryonic development. When remnants of this duct persist, they can form cysts known as thyroglossal duct cysts. Although generally benign, these cysts can undergo malignant transformation, most commonly into papillary carcinoma. Here, we report a case of thyroglossal duct carcinoma in a 22-year-old woman who presented with submental swelling. Imaging revealed features suggestive of malignancy, including microcalcifications and irregular solid components within the cyst. However, multiple fine-needle aspiration cytology (FNAC) procedures failed to detect malignancy. Based on the imaging findings, the patient underwent Sistrunk surgery, and postoperative histopathological analysis confirmed papillary carcinoma arising from a thyroglossal duct cyst. The diagnosis was challenging due to the tumor's localization within a limited area of the cyst. One year after surgery, the patient showed no signs of recurrence or metastasis. This case highlights the importance of considering malignancy in midline neck masses, even when FNAC results are inconclusive, and underscores the role of early diagnosis and appropriate surgical intervention.