A man in his 20s with a 2-month history of left chest pain and gradually enlarging mediastinal mass presented with new-onset intermittent hemoptysis. Coronary computed tomography (CT) angiography revealed a giant left anterior descending artery aneurysm surrounded by unenhanced pseudoaneurysm (Figure, A). Findings on the chest CT suggested communication of the partially thrombosed pseudoaneurysm with the adjacent bronchi (Figure, B) given the proximity and associated ground-glass airspace disease, which represented pulmonary hemorrhage and the cause of the intermittent hemoptysis. The patient underwent aneurysm resection and coronary artery bypass grafting. Unfortunately, however, he died of graft dehiscence leading to cardiac tamponade after discharge. It is important to be aware that ruptured coronary artery aneurysm can mimic mediastinal mass,1 a condition that requires timely surgical intervention.