Primary Pleural Tuberculosis Presenting With Noncaseating Granulomas: A Diagnostic Challenge.

Tuberculous pleural effusion is the second most common form of extrapulmonary tuberculosis after tuberculous lymphadenitis. Despite its frequency, diagnosis remains challenging due to its paucibacillary nature, and confirmation often requires invasive procedures. We report a 26-year-old male with no significant medical history who presented with persistent dyspnea, cough, and left-sided chest pain after recent travel to Pakistan. He denied known tuberculosis exposure. Imaging demonstrated a left pleural effusion, and thoracentesis revealed a lymphocytic exudate with elevated adenosine deaminase. Pleural fluid acid-fast bacilli smear and tuberculosis polymerase chain reaction were negative. Given the high clinical suspicion for tuberculosis, the patient underwent thoracoscopy with pleural biopsy, which demonstrated noncaseating granulomas. Although the histopathological findings were atypical, empiric antituberculous therapy was initiated. One month later, pleural biopsy cultures grew Mycobacterium tuberculosis, confirming the diagnosis. Pleural tuberculosis remains difficult to diagnose, as conventional microbiological tests are highly specific but have limited sensitivity. This case highlights the critical role of pleural biopsy in guiding early management and underscores that empiric therapy should be strongly considered when clinical suspicion and epidemiologic risk factors are high, even if initial diagnostic studies are negative.