Subacute normotensive cardiac tamponade as the initial presentation of metastatic lung adenocarcinoma: a case report.

BACKGROUND: Malignant pericardial effusion as the initial presentation of lung cancer is rare, and its diagnosis can be challenging, particularly when clinical features mimic common infectious or cardiogenic conditions. This case highlights the value of echocardiography and pericardial fluid cytology in identifying occult malignancy in patients with persistent cardiorespiratory symptoms and inconclusive initial workup. It also draws attention to the atypical occurrence of lung adenocarcinoma in a female patient, in whom breast cancer is more commonly associated with malignant pericardial effusion.

CASE PRESENTATION: A 54-year-old Malaysian woman of Chinese ethnicity, presented with a 3-week history of productive cough, low-grade fever, and exertional dyspnea. She was initially treated for community-acquired pneumonia with right parapneumonic effusion. Despite intravenous antibiotics and pigtail drainage of an exudative pleural effusion, her symptoms persisted. Computed tomography pulmonary angiography (CTPA), performed to rule out pulmonary embolism, revealed subsegmental emboli and circumferential pericardial effusion with reflux into the inferior vena cava. Echocardiography confirmed tamponade physiology despite normotension. Urgent pericardiocentesis drained 600 mL of hemorrhagic fluid, with cytology revealing malignant adenocarcinoma cells. PET-CT subsequently identified a hypermetabolic right upper lobe lung mass with widespread metastases to the pleura, pericardium, bones, adrenal glands, and subcutaneous tissues. She was referred for further oncologic and respiratory management.

CONCLUSIONS: This case demonstrates how subacute, normotensive cardiac tamponade can present subtly and be easily overlooked. In patients with persistent tachycardia and unexplained effusions, particularly when initial imaging and pleural fluid cytology are inconclusive, early echocardiographic assessment and pericardial fluid analysis are essential. Multidisciplinary collaboration enabled timely identification of an underlying malignancy, reinforcing the need for a high index of suspicion when evaluating hemorrhagic pericardial effusions.