Non-Hodgkin's lymphoma can mimic renal adenocarcinoma with inferior vena caval involvement.

Genitourinary involvement in both Hodgkin's and non-Hodgkin's lymphomas is common and can be confused with other benign and malignant urologic conditions. While lymphoma commonly produces vascular and ureteral encasement, intraluminal vascular involvement is rare. Indeed, there are no previous reports of renal lymphoma with tumor thrombus extending into both the renal vein and inferior vena cava. We describe the first reported case of lymphoma mimicking a Stage IIIA renal adenocarcinoma with tumor thrombus in the renal vein and the inferior vena cava. Renal lymphoma should be considered in the differential diagnosis even when tumor thrombus is present in the renal vein or vena cava.