The identification of vascular pathologies of the mediastinum is very important for the prevention of complications during the interventional procedure. A rare developmental anomaly of inferior vena cava (IVC): the interrupted IVC continues with azygos vein in thorax. And then, the azygos vein merges with the superior vena cava (SVC) and pours into the right atrium. The incidence is reported to be 0.6%. It is a crucial application to distinguish the enlarged azygos vein from the right paratracheal mass and lymph node radiologically and clinically.