Eosinophilic pleural effusion in adults at Srinagarind Hospital

The presence of pleural eosinophilia remains a controversy in etiology and prognosis. We conducted this study to evaluate the etiology of eosinophilic pleural effusion and to define the factors that determine malignancy in eosinophilic pleural effusion. Between 1 August 1994 and 1 July 2000, 50 patients were diagnosed with eosinophilic pleural effusion; 35 men and 15 women averaging 56.4 years of age. Most (96%) had exudative pleural effusion. Malignancy was the most common (46%) established cause followed by tuberculosis (10%), parapneumonic effusion (8%), and empyema thoracis (2%). We encountered only one case of pneumothorax and parasitic pleural effusion (from Strongyloides stercoralis). Unknown causes constituted 22% of cases. The etiology of those who had previously undergone thoracocentesis did not differ from those having their first thoracocentesis. Patients with malignant pleural effusion had significant longer duration of clinical symptoms (> or = 1 month) and weight loss than benign pleural effusion. The median duration of symptoms in benign pleural effusion was 14 days. Fever was more characteristic in patients with benign than in those with malignant pleural effusion. The percentage of eosinophils in pleural fluid and blood did not differ between the two groups. Pleural fluid eosinophils in malignant vs benign pleural effusion were 26.6% (range 10% to 63%), and 30.6% (range 10% to 93%), respectively. We concluded that, pleural eosinophilia did not indicate benign conditions which would spontaneously resolve. Malignant pleural effusion should be considered especially in areas malignancy is prevalent.