CASE PRESENTATION: A 52-year-old male smoker from Vietnam presented to our hospital with progressive dyspnea and cough. On admission, he was tachycardic to 112 beats/minute, tachypneic to 28 breaths/minute, and hypoxemic, with an oxygen saturation of 91% on 4L of oxygen. CT angiogram of the chest demonstrated a pleural effusion occupying the entire left hemithorax, a moderate pericardial effusion, and a subsegmental pulmonary embolism. EKG revealed low QRS voltage and electrical alternans, and echocardiography showed a large circumferential pericardial effusion with right ventricular diastolic collapse indicative of tamponade physiology. A pericardial drain and left chest tube were placed, both with return of sanguineous fluid. Chest imaging following drainage of the pleural effusion revealed a mass involving the lingula and left lower lobe, and pericardial fluid cytological analysis demonstrated malignant cells consistent with adenocarcinoma. Video-assisted thoracoscopy and pericardial window were performed, and pleural and pericardial biopsies confirmed lung adenocarcinoma. Tuberculosis was ruled out with negative sputum cultures for acid-fast bacteria and lack of adenosine deaminase in the pleural fluid. Given the advanced stage of his disease, the patient opted for palliative chemotherapy with carboplatin and pemetrexed.