[Follicular Thyroid Carcinoma Diagnosed with Lung Metastasis Six Years After Thyroid Surgery:Report of a Case].

A 72-year-old man was diagnosed with gastric cancer. Preoperative chest computed tomography (CT) revealed three nodules in the right lung. The patient had no history of malignant disease and had undergone surgery for thyroid follicular adenoma six years previously. Based on the morphology of the nodules, the right lower lobe nodule was suspected to be a primary lung cancer, whereas the right upper and middle lobe nodules were suspected to be lung metastases secondary to lung or gastric cancer. After distal gastrectomy, thoracoscopic wedge resection was performed for the pulmonary nodules. The right lower lobe pulmonary nodule was diagnosed as primary lung cancer, and the right upper and middle lobe pulmonary nodules were diagnosed as lung metastases from thyroid follicular carcinoma. When a patient with a history of thyroid follicular adenoma presents with a lung nodule, lung metastasis from thyroid follicular carcinoma should be considered.