A rare case of left innominate vein aneurysm mimicking thymoma.

Thoracic venous aneurysms are very rare conditions, even more unusual from left innominate vein. We report a case of a 57-year-old male who presented an anterior mediastinal mass suspicious of thymoma by chest computed tomography. Median sternotomy was performed aiming for total thymectomy, but intraoperative findings and final pathology confirmed the diagnosis of left innominate vein aneurysm. The patient underwent aneurysmectomy and reconstruction of the left innominate vein. The patient remains well 2 years after surgery. The new thoughts provoked by this case are that video-assisted thoracic surgery for this condition is dangerous and mediastinal mass should be evaluated further by magnetic resonance imaging, venography or venous phase computed tomography.