[Mediastinal lymph node metastasis of thyroid cancer occurring 15 years after the initial operation; report of a case].

A 71-year-old woman was found to have an abnormal shadow on a chest X-ray. Fifteen years earlier she had undergone a subtotal thyroidectomy for thyroid cancer without any lymph node metastasis. Chest computed tomography (CT) revealed a mediastinal tumor with full of blood stream. Since the positron emission tomography (PET) disclosed an increased uptake of fluoro-2-deoxy-D-glucose (FDG) in the tumor, a malignant lymphatic tumor was therefore suspected. An immunohistological examination of biopsy specimens taken by thoracoscopic procedure demonstrated tumor to be lymph node metastasis of the previous thyroid cancer. After a tumor resection by means of a thoracotomy and total thyroidectomy, the patient was scheduled to receive radioiodine therapy. The previously reported cases are also herein reviewed.