A patient with disseminated diffuse histiocytic lymphoma had persistent electrocardiographic (ECG) signs of acute myocardial infarction without clinical, enzymatic, or hemodynamic evidence of myocardial necrosis. The ECG findings were felt to be secondary to myocardial tumor invasion by antemortem noninvasive testing. This was confirmed by postmortem examination. Based on this report and a literature review, the particular ECG findings noted (lateral leads) are felt to be highly predictive of direct tumor invasion in this setting.