PECAM1 and heart cancer: Immunohistochemical analysis showed that the tumor cells were positive for CD31 and ERG.<h4>Diagnoses</h4>Based on the clinical presentation, imaging findings, and immunophenotypic evidence, the patient was diagnosed with primary cardiac angiosarcoma.<h4>Interventions</h4>The patient received regular postoperative chemotherapy.<h4>Outcomes</h4>After regular follow-up for 8 months, the patient was transferred to continue chemotherapy and died due to multiple metastatic tumors.<h4>Lessons</h4>Primary cardiac angiosarcoma is a rare malignant cardiac tumor.