BackgroundCardiac hemangiomas are rare benign vascular tumors that can occur in any cardiac layer: endocardium, myocardium, or epicardium. Histologically, cardiac hemangiomas may be classified as capillary, cavernous, or arteriovenous; venous hemangiomas are extremely rare.Case presentationA 46-year-old man reported experiencing precordial discomfort. Computed tomography revealed a massive tumor adjacent to the right ventricle. The right coronary artery was found to be located at the center of the tumor. Cardiovascular angiography showed that the artery was completely encased by the tumor without any obstruction and that the right ventricular lumen was compressed by the tumor. Surgical debulking of the tumor was performed under cardiopulmonary bypass, and the frozen section led to a diagnosis of benign hemangioma. The tumor was debulked as much as possible until the right coronary artery appeared. For decompression of the heart, the pericardium was left open to the thoracic cavity and unsutured. Histopathologic examination revealed a diagnosis of epicardial venous hemangioma.ConclusionsCardiac hemangioma should be included in the differential diagnosis of mediastinal tumor in reference to the location and flow of the coronary artery. Surgical resection, or at least tumor debulking, is required to confirm the diagnosis and prevent further complications and has a favorable clinical outcome.