Wilms' tumor with metastasis to the left testis.

Wilms' tumors account for the vast majority of renal neoplasms in infants and children. Common areas for metastases include the lung, liver, and contralateral kidney. Less common sites include the bone, skin, brain, and orbit. We report a case of Wilms' tumor in a 13-month-old boy who, after radical left nephrectomy, developed a left testicular mass that turned out to be metastatic Wilms' tumor. The epidemiology, case history, review of the literature, and possible etiology of this rare site of metastatic Wilms' tumor are discussed.