[Aneurysmal dilatation of the superior vena cava]

A case of aneurysmatic dilatation of the vena cava superior is presented. This lesion is rare and not commonly taken into consideration in the differential diagnosis of anterior mediastinal masses. Chest X-rays taken during inspiration and expiration and in the standing and reclining positions (particularly the second and fourth) revealed changes in the size of the mediastinal mass and pointed clearly to its venous nature. This deduction was then confirmed angiographically.