A case of metastatic renal cell carcinoma to thyroid gland.

Metastasis to the thyroid gland from distant cancer is rare, and, in some cases, is a diagnostic challenge. Here, we report a case of metastatic renal cell carcinoma of the thyroid gland. A 77-year-old man presented with a neck mass detected about 1 month previously. He had undergone a right nephrectomy owing to renal cell carcinoma 14 years previously. Fine needle aspiration cytology showed a few atypical follicular cells with nuclear atypia. Under a tentative diagnosis of papillary thyroid carcinoma, a total thyroidectomy was performed. The histologic and immunohistochemical studies of the surgical specimens indicated that the thyroid masses were metastatic renal cell carcinoma to the thyroid.