Intracardiac Ewing-Like Sarcoma: A Diagnostic and Therapeutic Challenge.

Ewing-like sarcomas are rare malignancies that typically arise in bone or soft tissue, with intracardiac presentations being exceptionally uncommon and associated with diagnostic uncertainty and high mortality due to anatomical constraints and therapeutic challenges. We report the case of a 22-year-old male who presented with progressive dyspnea and was found to have a large biatrial mass originating from the interatrial septum, resulting in atrial obstruction, pericardial effusion, and reduced systolic function. Subtotal surgical resection revealed a malignant small round cell tumor with an immunohistochemical profile positive for CD99 and NKX2.2, consistent with an Ewing-like sarcoma, although molecular confirmation was not available. Postoperative treatment with systemic chemotherapy was complicated by severe neutropenia, ventilator-associated pneumonia, and superimposed cardiogenic compromise, culminating in death on hospital day 35. Intracardiac Ewing-like sarcomas represent a diagnostically challenging and highly aggressive entity with a grave prognosis due to limited surgical resectability, hemodynamic compromise, and heightened susceptibility to treatment-related complications. This case highlights the narrow therapeutic window in patients with cardiac involvement and underscores the importance of multidisciplinary evaluation and careful administration of intensive therapy.