Diagnostic Utility of Pleural Fluid Eosinophilia

Diagnostic utility of eosinophilic pleural effusion (EPE) is still the matter of controversy. Some earlier studies have showed that pleural fluid eosinophilia considerably reduces the probability of malignancy, while some later analyses were not able to confirm such an observation. To evaluate the diagnostic significance of EPE the retrospective study of all patients with pleural effusion (PE) managed in our hospital between 1995 and 2001 has been undertaken. We analyzed 915 patients with PE and 1086 pleural effusions subjected to a biochemical, cytological and bacteriological examinations. We identified 72 (7.9%) patients with EPE and 82 EPEs liquid (7.5%) among them. The group of patients with EPE consisted of 41 (57%) males and 31 (43%) females; average age 62.2 year (range 21.0–94.0). Etiologic distribution showed the largest subgroup were patients with malignant EPE (n = 28, 38.9%) followed by idiopathic EPE (n = 12, 16.7%) and parapneumonic EPE (n = 11, 15.3%). Looking for predictors of malignancy in EPE we found some differences between malignant and nonmalignant EPE: patients with malignant EPE were older (67.9 ± 13.6) then patients with nonmalignant EPE (58.7 ± 15.6; p < 0.015), and have higher percentage of lymphocytes in PE (47.9 ± 16.9 vs. 37.9 ± 18.9; p < 0.03). Similarly we noticed some differences between two largest groups (malignant and idiopathic PE). Patients with malignant PE were older (67.9 ± 13.6 vs. 53.9 ± 13.6 yrs; p = 0.005), had lower pleural fluid eosinophilia (25.2 ± 15.3% vs. 41.4 ± 21.0%; p = 0.01) and higher percentage of lymphocyte in PE (47.9 ± 16.9 vs. 29.6 ± 19.1%; p = 0.004). We conclude that pleural fluid eosinophilia cannot be considered as predictor of nonmalignant etiology. The older age and the higher number of lymphocytes in EPE might suggest malignant etiology of pleural effusion.