An idiopathic azygos vein aneurysm mimicking a mediastinal mass.

Azygos vein aneurysms are very rare causes of mediastinal masses and are usually accidental findings on chest roentgenography. Most are detected in patients with portal hypertension or venous malformations. An idiopathic azygos vein aneurysm is assumed to be congenital and is much more exceptional. We present the case of a 76-year-old man who underwent excision of an idiopathic azygos vein aneurysm by video-assisted thoracoscopic surgery (VATS).