Clinically significant, isolated metastatic disease to the thyroid gland

Despite being second only to the adrenal glands in terms of relative vascul ar perfusion, the thyroid gland is a rare site of metastatic disease; but w hen thyroid metastases occur, long-term survival has been reported to be di smal. To determine the incidence and management of isolated, metastatic dis ease to the thyroid, we reviewed our clinical experience. Between June 1986 and August 1994 ten patients underwent thyroidectomy for isolated, metasta tic disease of nonthyroidal origin (mean +/- SD age 58 +/- 6 years, 30% fem ale). The primary tumors sere renal cell carcinomas (RCCs) (n = 5), esophag eal adenocarcinoma (n = 1), pulmonary squamous cell carcinoma (n = 1), gast ric leiomyosarcoma (n = 1), lingual squamous cell carcinoma (n = 1), and pa rotid gland carcinoma (n = 1). Three patients underwent preoperative fine-n eedle aspiration (FNA), all of which were suggestive of metastatic disease. The mean time from resection of the primary tumor to thyroid metastases wa s 3.5 +/- 6.0 years (range 0-19.5 years). Total thyroidectomy (n = 5) or lo bectomy (rr = 5) was performed without morbidity or mortality. After a medi an follow-up of 5.2 years six patients are alive and mo are free of disease . Moreover, no patients have had recurrent disease in the neck Thus carcino mas metastatic to the thyroid represent a rare cause of clinically signific ant thyroid disease, with RCCs comprising 50%. Most thyroid metastases (80% ) present within 3 years of primary tumor resection, but with RCC they can occur as late as 19 years. The diagnosis of metastatic disease should be su spected in patients with even a remote history of cancer, especially RCC, a nd an FNA revealing clear cell or spindle cell carcinoma. Contrary to previ ous reports, long-term survival can be achieved after resection of the meta static tumor. Furthermore, thyroidectomy may also palliate/prevent the pote ntial morbidity of tumor recurrence in the neck.