Acute Encephalopathy and Cardiac Tamponade as Initial Presentations of High-Grade B-Cell Lymphoma.

Cardiac tamponade is a life-threatening emergency caused by the accumulation of pericardial fluid, resulting in impaired cardiac filling. Although malignancy is a recognized cause of pericardial effusion, cardiac tamponade is a rare initial presentation of high-grade B-cell lymphoma (HGBCL) and may pose a diagnostic challenge because of its nonspecific clinical manifestations. A 67-year-old man with a history of hypertension, hyperlipidemia, and schizophrenia presented from a group home with acute altered mental status and dyspnea. Initial computed tomography of the head was negative for acute cerebrovascular pathology but incidentally demonstrated a large pericardial effusion and bilateral pleural effusions. Laboratory evaluation revealed severe hyponatremia, elevated B-type natriuretic peptide, and rhabdomyolysis. Transthoracic echocardiography confirmed a large circumferential pericardial effusion with findings concerning for cardiac tamponade, prompting emergent pericardiocentesis with drainage of 2.2 L of hemorrhagic fluid. Although he initially improved, his hospital course was complicated by hypoxemic respiratory failure requiring mechanical ventilation, persistent bilateral pleural effusions, and atrial arrhythmias. Cytologic examination of pleural fluid demonstrated HGBCL. The patient subsequently underwent a pericardial window for recurrent pericardial effusion, improved clinically, was successfully extubated, and was discharged with outpatient hematology follow-up to initiate systemic chemotherapy. This case illustrates cardiac tamponade as a rare but potentially fatal initial manifestation of HGBCL. Recognition of hemorrhagic pericardial effusion as a possible presentation of occult hematologic malignancy is critical, as prompt pericardial decompression combined with timely diagnostic evaluation can facilitate early oncologic treatment and improve clinical outcomes.