Background <p>Ascending aortic thrombus is an uncommon entity that may mimic primary aortic tumors. When aortic masses coexist with suspected coronary stenosis, conventional coronary angiography may increase the risk of thrombus embolization. We describe a case in which an ascending aortic thrombus produced imaging features suggestive of both aortic tumor and coronary disease, and demonstrate the diagnostic value of intraoperative direct coronary angiography.</p> Case presentation <p>A 60-year-old man presented with a two-year history of chronic dry cough. Transthoracic echocardiography revealed a mildly mobile 1.5 × 2.5&#xa0;cm weakly echogenic mass on the anterior ascending aorta. Transesophageal echocardiography confirmed a 1.6 × 2.8&#xa0;cm homogeneous, smooth-surfaced mass with a broad attachment to the aortic intima and no intimal tear or vascularity. Coronary computed tomography angiography showed a severe mid–left anterior descending artery stenosis, though the mass was distant from coronary ostia. Preoperative coronary angiography was avoided because of the high risk of thrombus embolization during angiography. During surgery, intraoperative direct coronary angiography via a cardiopulmonary perfusion needle excluded significant coronary artery disease. The mass was excised intact; pathology revealed an organized thrombus with myxoid degeneration. Recovery was uneventful, and the patient remained asymptomatic at follow-up.</p> Conclusions <p>Diagnosis of an ascending aortic mass relies on careful multimodality imaging, and surgical excision can be performed safely. When conventional coronary angiography is not feasible, intraoperative direct angiography provides a reliable alternative for assessing coronary anatomy.</p>