Unmasking Diffuse Large B-Cell Lymphoma: A Challenging Case of Acute Cardiac Tamponade in the Setting of Right-Sided Heart Mass Invasion.

Cardiac metastases, particularly those originating from non-Hodgkin lymphoma, are often underdiagnosed and represent a rare but critical manifestation of advanced cancer. This case report discusses a 57-year-old female with a history of hypertension who initially presented with symptoms of cardiac tamponade, leading to the discovery of a large cardiac mass, ultimately diagnosed as diffuse large B-cell lymphoma following a cytological examination of the pericardial fluid and lymph node biopsy. Further imaging, including echocardiography and computed tomography scans, showed extensive metastasis to the pericardium, mediastinum, and other areas, such as the thyroid and peritoneum. Despite the prompt initiation of management, the patient suffered a massive pulmonary embolism, highlighting the poor prognosis associated with metastatic cardiac lymphoma. This case underscores the importance of bedside echocardiography as a rapid initial method for identifying cardiac tamponade, as well as maintaining a high index of suspicion for hematologic malignancies in patients presenting with unexplained pericardial effusions. It emphasizes the need for comprehensive diagnostic approaches and multidisciplinary management to improve patient outcomes in this rare and challenging clinical scenario.