[A case of solitary metastasis from renal cell carcinoma to the thyroid gland].

A case of solitary metastasis with renal cell carcinoma to the thyroid gland is presented. The patient was a 54-year-old man found to have an abnormal mass in the neck. He had a past history of radical nephrectomy orignating from the right renal cell carcinoma 5 years earlier (pT2N0M0, G2 > 3, alveolar type, clear cell subtype). Ultrasonography revealed a tumor mass in the right hemithyroid gland. Right hemithyroidectomy was performed on April 19, 1995. Histopathologically, the removed thyroid tumor showed clear cell carcinoma. The possibility of a primary thyroid tumor was ruled out by immunohistochemical thyroglobulin staining, and the present case was thus diagnosed as of metastatic thyroid tumor of renal cell carcinoma. The present case is the 12th case of thyroid solitary metastasis of renal cell carcinoma reported in Japan to date.