Pleural fluid cytology, biochemistry and adenosine deminase level study in differentiating tubercular and non tubercular causes of pleural effusion

Abstract

IntroductionTuberculosis (TB) is one of the commonest infectious disease burdens of developing countries. Bangladesh is ranked sixth in the world of tuberculosis with around 300000 new cases per year.1 TB usually affects lung but extra pulmonary TB is also common and occurs at around 4% of all TB cases. 2 Among the extra pulmonary TB cases tuberculous pleural effusion (TPE) is the most common form. 3 Diagnosis of pulmonary TB is done by sputum for Acid Fast Bacilli (AFB). But the diagnosis of TPE is challenging as percentage of finding AFB in pleural fluid or typical histopathology of pleural biopsy is very low and AFB culture is time consuming, though they are gold standard. 4 Also the expertise and centre doing pleural biopsyis lacking in high incidence areas of TB in our country. ELISA, PCR and TB interferon tests are very expensive as well. Pleural TB occurs as a result of a TB antigen entering the pleural space, usually through the rupture of a subpleural focus, followed by a local, delayed hypersensitivity reaction mediated by CD4+ T lymphocytes and macrophages. The activated macrophages enter the pleural cavity, producing adenosine deaminase during its proliferation process.