A diagnostic trap: Malignant pericardial effusion mimicking tuberculous pericarditis

A middle-aged male with a history of treated pulmonary tuberculosis and industrial asbestos exposure complained of increasing dyspnea and chest pain for 15 days. Upon examination, he was tachycardic (100/min), tachypneic (24/min), hypotensive (100/60 mmHg), with raised jugular venous pressure and muffled heart sounds. A respiratory examination revealed decreased breath sounds in the right lung fields. Chest radiography (Fig. 1) demonstrated gross cardiomegaly with a globular cardiac silhouette suggestive of massive pericardial effusion, along with calcified pleural plaques on the right and post-tuberculous fibrotic changes with volume loss in the right upper lobe. Transthoracic echocardiography revealed a significant circumferential pericardial effusion (>20 mm) with symptoms of cardiac tamponade, including right atrial and ventricular collapse and a plethoric inferior vena cava (Adler et al., 2025 [1]). Emergency pericardiocentesis was performed. The aspirated fluid was haemorrhagic with an adenosine deaminase (ADA) level of 27.5 U/L, which was not supportive of tuberculous etiology (Porcel et al., 2010 [2]). Cytological examination revealed malignant cells. Contrast-enhanced computed tomography (Fig. 2) of the chest demonstrated a spiculated lesion in the left upper lobe. CT-guided biopsy confirmed non-small cell lung carcinoma. Immunocytochemistry was positive for thyroid transcription factor-1, consistent with lung adenocarcinoma. This case highlights a diagnostic challenge in tuberculosis-endemic regions, where prior TB history can lead to anchoring bias. Both tuberculous and malignant pericardial effusions may present similarly (Burazor et al., 2013 [3], Ben-Horin et al., 2006 [4]). Haemorrhagic fluid with low ADA should prompt evaluation for malignancy. Early cytological analysis is critical, as it has significant diagnostic and prognostic value in malignant pericardial effusion (Gornik et al., 2005 [5]).