Site-Specific Thoracoscopic Findings, Diagnostic Yield, and Predictive Morphology for Malignant versus Tubercular Pleural Disease

Background: Undiagnosed exudative pleural effusion frequently requires tissue diagnosis, particularly where tuberculosis and malignancy coexist. Medical thoracoscopy permits direct visualisation and targeted biopsy, but the diagnostic relevance of site-specific pleural morphology remains incompletely defined.

Aims: To determine the diagnostic yield of medical thoracoscopy and evaluate whether site-specific thoracoscopic morphology can differentiate malignant from tubercular pleural disease.

Materials and Methods: This prospective observational study enrolled 30 adults with exudative pleural effusion that remained unexplained after clinical, radiological, biochemical, microbiological and cytological assessment. Thoracoscopy was performed under local anaesthesia with conscious sedation. Apical, mid-costal, lower-costal and diaphragmatic findings were recorded, targeted biopsies were obtained, and final diagnoses were established by histopathology with ancillary testing. Associations were examined using Fisher exact or chi-square tests, Mann-Whitney U tests, Spearman correlation and exploratory penalised regression.

Results: Thoracoscopy established a conclusive diagnosis in 29 of 30 patients (96.7%). Tubercular pleuritis accounted for 12 cases (40.0%), malignant disease for 14 (46.7%) and other benign disease for four (13.3%). Inflammation or hyperaemia (73.3%), pleural thickening (66.7%), nodules (56.7%) and adhesions (56.7%) were common. Apical disease most often appeared as inflammation or nodules (30.0% each), lower-costal disease as adhesions (33.3%) or thickening (30.0%), and diaphragmatic disease as inflammation (50.0%). Parietal pleural nodules were present in all malignant cases but only 3 of 12 tubercular cases and no other benign cases (p < 0.001); sensitivity, specificity, positive predictive value and negative predictive value for malignancy were 100%, 81.2%, 82.4% and 100%, respectively. Mean pleural-fluid adenosine deaminase was higher in tuberculosis than malignancy (66.4 versus 25.3 U/L; p < 0.001). Most patients (60.0%) had no complication; recorded adverse events were minor and self-limited.

Conclusion: Medical thoracoscopy provided very high diagnostic yield with acceptable safety. Pleural nodularity strongly favoured malignancy, whereas diffuse inflammation or hyperaemia and high pleural-fluid adenosine deaminase favoured tubercular or inflammatory disease. These visual patterns can guide targeted biopsy but should complement, not replace, histopathological confirmation.