Pleural tuberculosis (TB), a form of extrapulmonary TB, can be difficult to diagnose. High numbers of lymphocytes in pleural fluid have been considered part of the diagnostic criteria for pleural TB; however, in many cases, neutrophils rather than lymphocytes are the predominant cell type in pleural effusions, making diagnosis more complicated. Additionally, there is limited information on the clinical and laboratory characteristics of neutrophil-predominant pleural effusions caused by Mycobacterium tuberculosis (MTB). To investigate clinical and laboratory differences between lymphocyte- and neutrophil-predominant pleural TB, we retrospectively analyzed 200 patients with the two types of pleural TB. Of these patients, 9.5% had neutrophil-predominant pleural TB. Patients with lymphocyte-predominant and neutrophil-predominant pleural TB showed similar clinical signs and symptoms. However, neutrophil-predominant pleural TB was associated with significantly higher inflammatory serum markers, such as white blood cell count (P = 0.001) and C-reactive protein (P = 0.001). Moreover, MTB was more frequently detected in the pleural fluid from patients in the neutrophil-predominant group than the lymphocyte-predominant group, with the former group exhibiting significantly higher rates of positive results for acid-fast bacilli in sputum (36.8 versus 9.4%, P = 0.003), diagnostic yield of MTB culture (78.9% versus 22.7%, P < 0.001) and MTB detected by polymerase chain reaction (31.6% versus 5.0%, P = 0.001). Four of seven patients with repeated pleural fluid analyses revealed persistent neutrophil-predominant features, which does not support the traditional viewpoint that neutrophil-predominant pleural TB is a temporary form that rapidly develops into lymphocyte-predominant pleural TB. In conclusion, neutrophil-predominant pleural TB showed a more intense inflammatory response and a higher positive rate in microbiological testing compared to lymphocyte-predominant pleural TB. Pleural TB should be considered in neutrophil-predominant pleural effusions, and microbiological tests are warranted.

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Background and objective: The association between airflow limitation severity and post-operative pulmonary complications (PPCs) among COPD patients undergoing extra-pulmonary surgery is unknown. We evaluated the association between forced expiratory volume in 1 s (FEV 1 ) and PPC in COPD patients undergoing extra-pulmonary surgery. Methods: Using prospective cohort of PPC evaluation for extra-pulmonary surgery, we identified 694 COPD patients who conducted PPC evaluation before extrapulmonary surgery between March 2014 and January 2015 at a tertiary hospital, Seoul, Korea. Results: The overall incidence of PPC was 24.4%. The incidence of PPC in quintiles 1-5 of FEV 1 (% predicted) was 31.4, 25.8, 23.7, 21.6 and 19.7%, respectively (P for trend: 0.019). In fully adjusted multivariable models, the relative risks (RRs, 95% CI) for PPC comparing participants in quintiles 1-4 of FEV 1 (% predicted) with those in quintile 5 were 1.69 (1.03-2.79), 1.41 (0.83-2.37), 1.26 (0.75-2.11) and 1.30 (0.76-2.22), respectively (P for trend: 0.046). The association of severe airflow limitation with respiratory failure and post-operative exacerbations was stronger in participants who did not use bronchodilators compared with those who did. Conclusion: We found a progressive and significant relationship between severity of airflow limitation and the incidence of PPC in COPD patients undergoing extra-pulmonary surgery. Furthermore, perioperative bronchodilator use was associated with a reduced risk