Primary cardiac lymphoma (PCL) is rare and occurs more commonly in immunocompromised patients. It can present in various ways, and diagnosis is particularly challenging, especially for the unsuspecting physician. We report a case of PCL in an immunocompetent 55-year-old man who initially presented with pyrexia of unknown origin, chest pain, dyspnea, and few early clinical signs, but who was later found to have cardiac tamponade and a large cardiac mass on echocardiography and cardiovascular magnetic resonance. A high index of suspicion is needed to diagnose PCL, and echocardiogram remains an important diagnostic tool.
