Giant right coronary artery aneurysm presenting as a mediastinal mass.

Coronary artery aneurysms are commonly of atherosclerotic origin and are frequently asymptomatic. However, they may have varied presentations including angina, myocardial infarction, and sudden death. A case of a giant right coronary artery aneurysm presenting with acute myocardial infarction is presented, where the aneurysm appeared to be a mediastinal mass on transthoracic and transoesophageal echocardiography. Although computed tomography and magnetic resonance imaging of the heart suggested the correct diagnosis, definitive proof came from coronary angiography. Coronary artery aneurysms should be considered in the differential diagnosis of mediastinal masses.