Thrombosed saccular aneurysm of a sinus of Valsalva: unusual cause of a mediastinal mass.

A 33 year old man presented with a short history of slight fever and chest pain that was worse on inspiration. An electrocardiogram was consistent with pericarditis. Chest radiography, echocardiography, and computed tomography suggested the presence of a mediastinal tumour. At operation the mass was found to be attached to the right sinus of Valsalva and proved to be a large saccular aneurysm full of laminated thrombus.