Inferior vena cava obstruction presenting as an abdominal mass

Obstruction of the inferior vena cava (IVC) was observed as an abdominal mass on the plain radiograph in an asymptomatic patient. The obstruction had developed immediately below the renal veins, and markedly dilated varices were present. The appearance differed from that of the usual congenital caval variants and may have been the result of caval thrombosis in utero.