Sections of the tumor show cells arranged in sheets and nests separated by thin vascular septa (Image 03). The tumor is well delineated from adjacent normal parenchyma (Image 04) but it diffusely infiltrates the renal sinus soft tissues (Image 05). The cells have uniform nuclei with irregular nuclear contours and dispersed, even chromatin (Image 06). Nucleoli are inconspicuous. The cytoplasm is generally clear, but in some areas it is lightly eosinophilic (Image 07). Occasional mitoses are identified (Image 08) and focal necrosis is present (Image 09). Focally, the tumor invades the renal capsule and extends into the perinephric fat (Image 10). One perihilar lymph node shows metastatic tumor (Image 11). Tumor occludes and distends the renal vein (Image 12), but the margin of resection is free of tumor.