[Renal oncocytoma with synchronous contralateral renal cell carcinoma]

A 60-year-old male was admitted with bilateral renal masses with a diameter of 50 mm (right kidney), and 15 mm (left kidney) found incidentally by computed tomography. Renal angiography demonstrated neovascularization in the lower pole of the right kidney, but no remarkable findings in the left kidney. We could not deny the possibility of bilateral renal cell carcinoma. Right radical nephrectomy and left partial nephrectomy were performed. The histopathological finding revealed diagnosis of right papillary renal cell carcinoma and left oncocytoma. To our knowledge, this is the third case of renal oncocytoma with synchronous contralateral renal cell carcinoma reported in Japan.