Figure 1a. (a) Axial contrast material-enhanced CT image obtained through the abdomen shows a large, lobulated, heterogeneously attenuating mass of the posterolateral right kidney with involvement of the subcapsular and perinephric spaces. The areas of lower attenuation suggest the presence of hemorrhage and necrosis. (b, c) Sequential axial CT images from the same data acquisition as a show distortion of the renal collecting system from mass effect without definite invasion. There is normal enhancement of the inferior vena cava (IVC).