[Papillary Carcinoma Arising in Thyroglossal Duct Cyst in the Right Lateral Neck].

A 47-year-old woman was admitted to our institution with the chief complaint of a right cervical mass. Imaging examination findings showed a cystic mass of 25mm with a nodular lesion in the right cervical region. Therefore, we performed extirpation of the right cervical cystic mass to allow diagnosis of the lesion. The histopathological findings showed a partial thyroid tissue on the cyst wall covered with glandular epithelium or metaplastic squamous epithelium, and tumor cells proliferating in the papillary form. Considering the histopathological evidence of the characteristic epithelium of the thyroglossal duct cyst, the potential carcinogenesis from the remnant thyroid tissues, and the absence of primary tumor in the thyroid gland, the patient was diagnosed with thyroid papillary carcinoma arising from the thyroglossal duct cyst in the right lateral cervical region. We found recurrence of the right cervical lymph node at 1 year and 5 months after the initial operation. Thus, we performed dissection of the right cervical lymph nodes. Two years and 10 months after the operation, neither recurrence nor metastasis have been observed. It was suggested that, thyroid papillary carcinoma arising from the thyroglossal duct cyst should be taken into consideration when a lateral cervical mass lesion is found.