Giant Left Ventricular Intracavitary Mass: Diagnostic Challenges in Distinguishing Thrombus From Tumor.

Giant left ventricular (LV) intracavitary masses are rare and pose significant diagnostic and therapeutic challenges due to their high risk of systemic embolization and sudden death. We report two acute cases illustrating contrasting presentations and outcomes. The first case involved a 70-year-old man with acute bilateral ischemic stroke and a large mobile LV mass in the setting of ischemic cardiomyopathy and concurrent gastric adenocarcinoma; the patient deteriorated rapidly and died before advanced imaging could clarify the nature of the mass. The second case concerned a 52-year-old man presenting with acute coronary syndrome complicated by severe LV dysfunction and an apical aneurysm; echocardiography revealed a large apical mass that resolved completely with anticoagulation, confirming an LV thrombus. These cases highlight the difficulty of distinguishing thrombi from cardiac tumors using transthoracic echocardiography (TTE) alone and underscore the value of cardiac magnetic resonance imaging when feasible. Integrating clinical context, imaging findings, and disease evolution is critical for early recognition and appropriate management of LV masses to reduce the risk of embolic complications.