Neoplasms metastatic to the thyroid gland.

In this report, the incidence and pathologic factors of neoplasms metastatic to the thyroid gland in patients seen at the Mayo Clinic are examined. The most frequent primary tumors were renal cell carcinoma and adenocarcinoma of the breast. A review of recent studies of this topic at other institutions is also offered. It is suggested that fine needle aspiration of the thyroid gland be used diagnostically in all patients with a prior malignant tumor at a distant site who have a thyroid nodule. A therapeutic approach is suggested which limits thyroidectomy largely to instances of slow growing tumors without evident metastasis elsewhere.