This 31 y/o male presented with a palpable abdominal mass. Selected images from his abdominal CT shown above demonstrate a horseshoe kidney. That's the easy diagnosis for a radiologist. Hopefully you also observed the enlarged, rounded inferior vena cava, much larger than the aorta on all images. This finding is consistent with constrictive pericarditis. That was the easy diagnosis for the clinicians. The jugular venous distension and abnormal venous pulsation was obvious. Good thing someone still examines the patient! Equalization of pressures in the cardiac chambers was found at cardiac catheterization confirming constrictive pericarditis. The horseshoe kidney was incidental. I gave prizes for horseshoe kidney diagnosis alone, as I didn't think anyone would make the primary observation. No one did in the 85+ responses so don't feel bad about missing the finding. The clinicians didn't care about the IVC finding, they wanted to know what the mass was and most of you got that right. This is the reason a "jester/joker" was the prize this week, sometimes radiologists are right for the wrong reasons. ;-)