Contrast-enhanced CT of the chest of an 18-year-old shows a large anterior mediastinal mass (asterisk), which was subsequently diagnosed to be a germ cell tumour. The linear vascular structure (arrow) entering the posterior aspect of the superior vena cava is the azygous vein. It is to be noted that the appearance of azygous vein can vary and is dependent not only on its course, but also on the direction of the X-ray beam.