Mesothelial cells in pleural fluid: TB or not TB?

Eighty-five samples of pleural fluid obtained from 76 patients with biopsy-proven tuberculous pleurisy were examined cytologically. Numerous reactive mesothelial cells were present in only 1,2% of specimens examined. In contrast, 65,3% of pleural fluid aspirates obtained from a control group of patients in congestive cardiac failure contained marked mesothelial exfoliation. The suggestion that the presence of numerous, often highly reactive mesothelial cells in a pleural aspirate makes the diagnosis of tuberculosis unlikely is confirmed.