Abstract
Myxofibrosarcoma is an aggressive soft tissue sarcoma, previously known as myxoid variant of malignant fibrous histiocytoma. Primary cardiac myxofibrosarcomas are the rarest forms of cardiac malignant tumors that often remain asymptomatic until metastasis occurs. In this case report, we describe a rare left atrial cardiac myxofibrosarcoma in a patient with recurrent renal cell carcinoma. We discuss the multimodality imaging approach to diagnose and evaluate cardiac masses as well as imaging characteristics to differentiate cardiac masses from thrombus.