Diagnostic utility of eosinophils in the pleural fluid

This study was conducted to assess the prevalence of eosinophilia in 358 co nsecutive samples of pleural fluid (all cases corresponded to first thorace ntesis), to review the cause of eosinophilic pleural effusions, and to dete rmine whether the presence of eosinophils increases the likelihood of nonma lignant underlying disorders. Eosinophilic pleural effusions were identified in 45 patients (12.6%): mali gnant underlying conditions were diagnosed in 11 patients (24.4% with eosin ophilic effusions) and benign aetiologies were found in 27 patients. Benign aetiologies included uncomplicated paraneumonic effusion in 10 patients, t uberculosis in seven, complicated paraneumonic in five, liver cirrhosis in three, hydronephrosis in one and pulmonary thromboembolism in one. Seven pl eural effusions were idiopathic, There was no difference in the prevalence between eosinophilic and noneosinophilic effusions according to the differe nt diagnoses. With parameters of sensitivity, specificity, pretest and post -test probability and positive and negative predictive values for any preva lence figure using the Bayes' theorem and for any value of eosinophils (bot h in percentage or absolute numbers) in the pleural fluid (receiver operati ng characteristic curve) an adequate predictor of benign disease was not fo und. It is concluded that pleural eosinophilia at the initial thoracentesis cann ot be considered as a predictor of an underlying benign disorder.