A 56-year-old man with renal cell carcinoma in renal allograft. Findings: Coronal CT with intravenous contrast, arterial phase of abdomen showing heterogeneously enhancing mass lesion at the upper pole of renal allograft (white arrow) in the right iliac fossa with internal hypodense nonenhancing region (asterisk) suggesting necrosis (Technique: Siemens Somatom sensation 64-slice CT scanner, Coronal CT, KV 120, Eff mAs 105, Slice thickness 5 mm. Contrast: Iohexol 350, 70 mL, Arterial Phase