Primary Pleural Tuberculosis Presenting With Noncaseating Granulomas: A Diagnostic Challenge

IntroductionTuberculous pleural effusion is the second most common form of extrapulmonary tuberculosis after tuberculous lymphadenitis. However, its diagnosis remains challenging due to its paucibacillary nature, requiring invasive procedures for diagnosis confirmation.Presentation of CaseA 26-year-old male with no significant medical history presented with persistent dyspnea, cough, and left-sided chest pain. He had a history of travel to Pakistan but denied known tuberculosis exposure. Initial imaging revealed a left pleural effusion, and thoracentesis showed a lymphocytic exudate with elevated adenosine deaminase. Pleural fluid tuberculosis polymerase chain reaction and acid-fast bacilli smear were both negative. Given high clinical suspicion for tuberculosis, he underwent thoracoscopy with pleural biopsy, which demonstrated non-caseating granulomas. Despite the atypical histology, he was empirically started on anti-tuberculous therapy. One month later, pleural biopsy cultures confirmed Mycobacterium tuberculosis, solidifying the diagnosis.DiscussionPleural tuberculosis is challenging to diagnose, as conventional microbiological tests often have limited reliability. While acid-fast bacilli smear and tuberculosis polymerase chain reaction are highly specific, their sensitivity remains low, limiting their diagnostic utility. In contrast, pleural biopsy is the most important diagnostic tool, as it provides both histopathologic and microbiological confirmation. In this case, the biopsy findings played a crucial role in guiding early treatment despite negative initial microbiological results, ultimately leading to a confirmed diagnosis.ConclusionEmpiric treatment should be strongly considered in patients with suspected tuberculous pleuritis, even if initial diagnostic tests are negative, especially when the pretest probability is high due to prior tuberculosis exposure, or travel from endemic regions.