Abstract
Thyroglossal duct cancer is a rare disease, with an incidence rate of 1.6-1.9％ among patients with thyroglossal duct cysts. The most common histological type is papillary carcinoma （80％）. Squamous cell carcinoma accounts for approximately 6％. A 26-year-old male presented to our hospital with a chief complaint of anterior neck swelling. Below the chin, a polycystic mass of 14cm in size and swelling of multiple lymph nodes were observed. Papillary carcinoma was detected using aspiration cytology, and thyroglossal duct cancer was diagnosed based on imaging findings. Tumor resection with total thyroidectomy and bilateral neck dissection was performed using the Sistrunk method. Postoperative histopathology revealed diffuse transition from papillary carcinoma to squamous cell carcinoma in a part of the tumor, and similar pathological findings were observed in some of the metastatic lymph nodes. Squamous cell carcinoma of the head and neck region has been found to have a poor prognosis, and while the transition from papillary carcinoma to squamous cell carcinoma is thought to affect the prognosis, based on the available literature we believe that the prognosis depends on the original histological type of the tumor.
