CT findings of incidentally diagnosed metastatic papillary thyroid carcinoma in cervical lymph nodes: A case report of patient with maxillary gingival squamous cell carcinoma

Papillary thyroid carcinoma is the most common pathological type of thyroid cancer. Lymph node metastasis in patients with papillary thyroid carcinoma is common. We report a case of cervical lymph node metastasis of papillary thyroid carcinoma in a patient with maxillary gingival squamous cell carcinoma. A 77-year-old man presented with swelling and pain on the left side of the maxilla. Maxillary gingival squamous cell carcinoma without cervical lymph node metastasis was suspected from the CT images of the lesion in addition to panoramic radiography. A partial biopsy of the maxillary region was performed. Histopathological diagnosis was well to moderately differentiated squamous cell carcinoma. Chemoradiotherapy (CDDP: 400 mg and external radiation: 60 Gy) was performed for the maxillary tumor, and post-chemoradiotherapy outcomes were good for the maxillary tumor. However, contrast-enhanced CT taken 4 months after the primary treatment showed increase of the superior internal jugular node with heterogeneous enhancement and the mid internal jugular node with homogeneous enhancement and flecks of calcification on the left side of the neck. Cervical lymph node metastasis of the left maxillary gingival carcinoma after chemoradiotherapy was suspected from the CT images. Neck dissection was performed. Histopathological diagnosis was cervical lymph node metastasis of the left maxillary gingival squamous cell carcinoma and papillary carcinoma of the thyroid.