Diagnostic Yield of Closed Pleural Biopsy in Undiagnosed Exudative Pleural Effusions.

In our practice, etiological diagnosis of pleural effusion is sometimes difficult despite cytological, biochemical and microbiological tests. The aim of the present study was to make an etiological diagnosis by means of closed pleural biopsy in undiagnosed pleural effusions. The study group consisted of patients with exudative pleural effusion where etiology was not determined by means of conventional cytological, biochemical and microbiological investigations. Pleural tissue was obtained by Abrams pleural biopsy needle. Pleural biopsy was subjected to histopathology, Ziehl-Neelsen (Z-N) staining and mycobacterial culture. Four hundred fifty eight patients with pleural effusion were screened over three years and 82 of them were found to have undiagnosed exudative effusion after investigations, as mentioned in the Method section. The age of the 82 subjects [56 (68.29%) men and 26 (31.71%) women] ranged from 15 to 65 years (mean 32.6). Histopathology showed epitheloid granuloma with caseation necrosis in 50 (60.9%) patients and non-specific chronic inflammation in 14 (17.1%) subjects. Ziehl-Neelsen stain was positive for acid fast bacilli (AFB) in 10 (12.2%) patients and culture of pleural tissue showed the presence of Mycobacterium tuberculosis in 18 (21.9%) patients. In the era of thoracoscopy, percutaneous closed needle pleural biopsy still holds a significant role in cases of undiagnosed exudative pleural effusions where thoracoscopy is not available, being also a cost effective approach for developing countries. It can achieve specific diagnosis among 86.6% of cases with undiagnosed exudative pleural effusions.