Nephroblastoma Arising in a Primary Testicular Teratoma in a Nonatrophic Testis of a 50-Year-Old Man

Extrarenal nephroblastoma is an extremely rare tumor thought to be related to teratoid tumors of germ cell origin. Because few cases have been reported, no standard method for categorizing and managing these tumors exists. To our knowledge, there have only been 3 adult cases of nephroblastoma arising in a germ cell tumor of testicular origin in a nonatrophic testis, all in men aged 19 to 22 years and with aggressive clinical courses. We report a case of nephroblastoma in a nonatrophic testis, with nephroblastoma being the only non–germ cell component, in an older patient and with a more indolent clinical course that was responsive to localized treatment.