THYROGLOSSAL DUCT CARCINOMA WITH CERVICAL LYMPH NODE METASTASIS

Abstract

　Thyroglossal duct cyst is one of the most common congenital abnormalities of the cervical region. Complications are rare, although appearance of a carcinoma has been counted as one of the complications. We present the case of a 49-year-old man with a small papillary carcinoma arising in a thyroglossal duct cyst, with cervical lymph node metastasis. He was admitted to another hospital with the diagnosis of a painless anterior neck mass. Neck mass excision was performed, and histopathology of the resected specimen revealed cervical lymph node metastasis from a papillary carcinoma. The patient was referred to our hospital at this time. Contrast-enhanced computed tomography at our hospital showed a heterogeneous mass measuring 8 mm in diameter in the infrahyoid region of the anterior neck, and also suspicious metastatic lymph nodes at level II and level VI in the right neck. FDG-PET/CT revealed a slightly higher uptake in the soft-tissue component of the anterior neck mass, which was located in front of the hyoid bone as compared to the thyroid gland. A Sistrunk operation with central and right modified radical neck dissection was performed. Histopathology of the resected specimen revealed a papillary carcinoma arising from the thyroglossal duct and metastatic papillary carcinoma in the cervical lymph nodes. In our case, thyroglossal duct carcinoma was diagnosed by initial detection of a metastatic papillary carcinoma in the cervical lymph node, although it typically presents as a midline palpable neck mass. It remains controversial whether papillary carcinoma in the thyroglossal duct develops de novo or as a type of metastasis from an occult tumor nidus in the thyroid gland, thyroglossal duct carcinoma may be considered when metastatic papillary carcinoma was identified in the neck lesion.