Thrombosed sinus of Valsalva aneurysm masquer ading as a cardiac tumour: a case report

BACKGROUND: An aortic sinus of Valsalva aneurysm (SVA) often remains undiagnosed until it ruptures. An SVA filled with thrombus can be challenging to diagnose accurately. CASE SUMMARY: A 70-year-old man was admitted with a clinical diagnosis of well-tolerated complete atrioventricular block (AVB). Transthoracic echocardiography revealed a spherical mass (43 × 49 mm) at the interatrial septum. Enhanced computed tomography (CT) showed a well-defined, hollow, and non-enhanced mass suggesting a cardiac tumour. However, 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT) showed no uptake in the mass. After implantation of a permanent pacemaker, anticoagulant therapy was started for paroxysmal atrial fibrillation. Two months later, follow-up evaluation by echocardiography and enhanced CT revealed an increase in size of the hollow interior cavity, suggesting thrombolysis by the anticoagulant. We diagnosed a non-coronary SVA filled with thrombus, which masqueraded as a cardiac tumour and may have caused complete AVB. CONCLUSIONS: We describe a rare case of a giant thrombosed SVA masquerading as a cardiac tumour. Initial 18F-FDG PET/CT and serial imaging studies were helpful in distinguishing it from a cardiac tumour.