CRA33 SMEAR-NEGATIVE PLEURAL TUBERCULOSIS MIMICKING ACS AND CAP: A REMINDER FROM AN ENDEMIC REGION

HY Chuah¹

¹Klinik Kesihatan Kampar, Perak, Malaysia

Introduction
Pleural tuberculosis is a common form of extrapulmonary tuberculosis. Diagnosis is often delayed due to non-specific symptoms and inconclusive initial tests. This case report describes a smear-negative pleural tuberculosis initially misdiagnosed as acute coronary syndrome (ACS) and community-acquired pneumonia (CAP), emphasizing the need to always suspect tuberculosis in endemic regions.

Case Presentation
A 37-year-old previously well woman presented to a health clinic with palpitations and left-sided chest pain for one week. She denied fever, cough, dyspnoea and constitutional symptoms. Electrocardiogram showed sinus tachycardia with T-wave inversion over V1–V4, raising suspicion for ACS. After antiplatelet loading, she was referred to hospital. There, her chest X-ray showed left pleural effusion. Troponin I was normal. She was treated for CAP with parapneumonic effusion and discharged with antibiotics.
She returned three weeks later with similar symptoms. Repeated chest X-ray showed worsening left pleural effusion, extending up to midzone. First thoracocentesis drained 1280cc clear fluid while the second one drained 1800cc after intrapleural fibrinolytics. Initial pleural fluid tests (AFB smear, Gram stain, culture, TB GeneXpert, TB PCR) were all negative. She was empirically treated for CAP. Cytology later revealed lymphocytic effusion and pleural fluid adenosine deaminase (ADA) returned markedly elevated at 320.7U/L. A diagnosis of pleural tuberculosis was made and anti-tuberculous therapy was initiated. Mycobacterial culture confirmed presence of Mycobacterium tuberculosis. She improved with treatment, with resolving symptoms and effusion on follow-up imaging.

Discussion and Conclusion
Smear-negative pleural tuberculosis can mimic cardiac or other infectious diseases like CAP leading to delayed diagnosis, particularly when the initial presentations suggest more common causes. In endemic areas, tuberculosis should remain a key differential diagnosis. Pleural fluid ADA is a valuable diagnostic tool for pleural tuberculosis.