Lung Metastasis From Thyroid Carcinoma Showing a Pure Ground-Glass Nodule

We report a rare case of lung metastasis of thyroid carcinoma showing a pure ground-glass nodule in a 68-year-old man who underwent total thyroidectomy and lymph node dissection in 2004. We followed the nodule growth, found 5 years after the surgery in the right lower lobe, using computed tomography and observed a gradual enlargement to 8 mm in 11 years. Postoperative pathology and immunohistochemistry revealed that the tumor was a papillary carcinoma that metastasized from the thyroid. This report may help clinicians recognize pure ground-glass nodules as lung metastasis of thyroid carcinoma and avoid misdiagnosis as lung adenocarcinoma.