A case of renal cell carcinoma solitarily metastasized to thyroid 20 years after the resection of primary tumor.

A case of renal cell carcinoma in a 69-year-old woman is reported. The woman developed a thyroid tumor recently. She has a history of nephrectomy done 20 years ago for a renal cell carcinoma. Based on the close resemblances of the histological features and cell nuclear DNA distributions of both tumors, the thyroid tumor was diagnosed as the secondary tumor from the renal cell carcinoma. In the review of the literature, this case of renal cell carcinoma seems to be that with the longest interval of years before solitary metastasis to the thyroid.