Cardiac Undifferentiated Pleomorphic Sarcoma with Hemorrhagic Changes, Mimicking Benign Myxoma: A Case Report.

When diagnosing cardiac tumors, it is important to consider factors such as the patient's age, tumor location, radiologic features, differentiation between benign and malignant tumors and to provide the surgeon with appropriate information. In this report, we present a case of two cardiac masses originating in the left atrium that were diagnosed as undifferentiated pleomorphic sarcomas through surgical resection. Imaging studies showed two masses attached to the posterior wall of the left atrium and mitral valve; hemorrhagic changes were suspected in these masses. Irregular thickening of the mitral valve suggests tumor invasion; however, the possibility of a mural thrombus should be excluded. Multiplicity, large size, and irregular mitral valve thickening suggest a malignancy. However, given the much higher incidence of myxomas, well-defined margins, and the fact that hemorrhagic changes can occur in large myxomas, the possibility of a benign tumor cannot be ruled out.