Columnar variant of papillary carcinoma in the thyroglossal duct cyst with progression to lung metastasis

Thyroglossal duct cyst (TGDC) carcinoma generally shows a favorable prognosis. If metastasis is present latently, it may not threaten the patient's life immediately. It has been shown, however, that larger than 1 cm papillary carcinoma (PC), level VI metastasis to the lymph node (LN), which is the nearest to the thyroid, independently predicts a worse prognosis. In the case presented herein, a 61-year-old female patient was diagnosed with an about 3 cm PC in the TGDC, particularly the columnar variant subtype, one of the aggressive variants. She had occult papillary thyroid microcarcinoma, but no LN metastasis. Even though she underwent the Sistrunk procedure and total thyroidectomy with central compartment neck dissection followed by high-dose radioactive iodine remnant ablation, however, the cancer cells spread to level IV neck LN, and finally to the lung. Therefore, when a patient is diagnosed with an aggressive histologic variant of PC in the TGDC, even without LN metastasis, the invasive surgical approach and close postoperative surveillance are necessary, with consideration of the risk of disease progression. Therefore, if it is possible to stratify the risk for patients, higher-risk patients can be offered a more invasive therapeutic approach.