Saccular aneurysm of the superior vena cava

: The authors report a case of a saccular aneurysm of the superior vena cava in a 38 year old female. The diagnosis could only be made at thoracotomy because of the additional difficulty posed by a complete thrombosis of the aneurysmal pocket, which produced a particularly deceptive CT image. This type of lesion is exceptionally rare as a cause of a mediastinal "tumour" since only 24 cases of congenital aneurysm of the superior vena cava have been reported, of which only 4 were of the saccular type.