A rare case of azygous vein aneurysm with cotriatrium dextrum.

Azygous vein aneurysm (AVA) is an infrequent entity for posterior mediastinal lesion and paratracheal mass. Usually asymptomatic, AVA is discovered during routine examination of a patient. The patho-etiology of the azygous vein aneurysm has not been fully understood till date, making it difficult to postulate the most common cause for its occurrence. Nonetheless, AVA has to be taken into consideration as a differential diagnosis for posterior mediastinal mass or right paratracheal lesion. The objective of this paper is to report a rare case of AVA and further discuss on its patho-etiology leading to the dilatation of azygous vein aneurysm.