Diagnostic yield and etiological spectrum of medical thoracoscopy-guided pleural biopsy in various exudative pleural effusions: experience from a rural tertiary center in north India

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Exudative pleural effusions still today remain a frequent diagnostic challenge. Approximately 20-40% of cases remain undiagnosed after a pleural fluid study and closed pleural biopsy. Medical thoracoscopy (MT), a new tool, enables direct visualization and targeted pleural biopsy, substantially improving diagnostic accuracy. The objective of this study was to determine the diagnostic yield, etiological profile, and procedure-related complications of MT-guided pleural biopsy in various groups of moderate to massive exudative effusions from a rural tertiary center in north India. In secondary objectives, we also analyzed the same in undiagnosed, hemorrhagic, and pyothorax patients as our experience with MT. This cross-sectional study was conducted and collected data over the years (2015-2024). A total of 103 patients (67 males, 36 females; mean age 47.2±17.4 years) with exudative pleural effusion (per Light’s criteria) and met inclusion exclusion criteria underwent semi-rigid MT under conscious sedation. Undiagnosed effusion was defined as exudative effusion with negative microbiological (cartridge-based nucleic acid amplification test, Gram stain culture, tuberculosis (TB) culture) and malignant cytological investigations, and pleural fluid ADA <70 U/L was considered. Histopathological findings were analyzed to determine diagnostic yield, etiological distribution, and complications. The overall diagnostic yield was 95.1% (98/103). Malignancy accounted for 37 (35.9%), TB for 29 (28.2%), and inflammatory lesions for 31 (30.1%); 1 case (0.97%) was sarcoidosis, and 5 (4.9%) were non-diagnostic. In the undiagnosed group (n=67), diagnostic yield was 94.0%, with malignancy [37 (55.2%)] as the leading cause, followed by TB [16 (23.88%)] and inflammatory lesions [9 (13.43%)]. Metastatic adenocarcinoma was the most common malignant subtype (35.1%). Among hemorrhagic effusions (n=30), 70% were malignant. Among 37 cases of pyothorax, it was detected that, based on histopathology, 9 patients (24%) had tuberculous pyothorax and one malignant case. Complications occurred in an overall 10.7% of patients, predominantly minor and safe. Mean chest tube duration was 2.8 days for TB, 5.8 days for inflammatory, and 6.7 days for malignant effusions. Overall, MT-guided pleural biopsy is a safe, minimally invasive, and high-yield diagnostic tool for exudative pleural effusions. It should be prioritized for undiagnosed pyothorax and hemorrhagic effusions to ensure definitive etiological diagnosis and evidence-based personalized management to avoid empirical use of antitubercular therapy.