An Innovative Approach to the Diagnosis of Cardiac Angiosarcoma.

We present a case of a 32-year-old female presenting with shortness of breath and increasing oxygen requirements. Further imaging discovered a large mass extending circumferentially into the pericardium, cardiac wall, and chambers, involving the anterior and middle mediastinum. Direct tissue biopsy of the mass for a diagnosis was unsafe. Therefore, advanced flow cytometric analysis for tumor marker expression of the malignant effusion was used to differentiate the mass as a vascular sarcoma, consistent with cardiac angiosarcoma. Additionally, cytometric analysis for programmed cell death protein 1 (PD1), programmed death-ligand 1 (PDL1), and cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) was also performed; a study seldom investigated for angiosarcomas but may have advantages over immunohistochemical analysis.