Assessment of the histopathological prototypes of the pleural fluid and granulomatous tissue reaction associated with pleural tuberculosis

PurposeThe aim of this study is to differentiate between the histopathological features of pleural tuberculosis both free and encysted forms of pleural effusion as regards pleural fluid cytology and pleural tissue granulomatous tissue reaction and assess the effects of combined microbial infection on histopathological and clinical residuals.Patients and methodsOne hundred and ninety patients were confirmed to be tuberculous by pleural tissue biopsy. Pleural fluid cytopathology and TB granulomatous tissue biopsy samples were studied.ResultsWithin histopathological features in TB pleural effusion is typical granulomatous TB reaction that was prevalent in both free and encysted forms of pleural effusion with high percentage (97% and 87.5% respectively). On the other hand, lymphocytic exudative smear was predominant in the free TB effusion group than both inflammatory and hemorrhagic ones (74.7% versus 23.5% and 1.8% respectively) while the encysted effusion group presented higher predominance to inflammatory exudative smear than other types (54.2% versus 41.7% and 4.2% respectively). Moderate cellularity was higher in percentage in both free and encysted groups 77.7% and 62.5% respectively. Also, langerhans cells prevailed in both effusion types. Lastly, non TB culture was present in all cases of encysted pleural effusions but accounted only for 3% of free effusion cases.ConclusionDifferentiation between free and encysted forms of pleural tuberculous effusion as regards effusion cytopathological criteria and pleural tissue histopathological patterns represent an important support in understanding the pathogenesis of pleural tuberculous tissue reactions and other positive cultural diagnosis can aggravate TB granulomatous reactions.