Luo W, et al. - By analyzing complete clinical data of 11 consecutive patients with idiopathic eosinophilic pleural effusion (IEPE), researchers tried to gain insight into the characteristics of IEPE as well as to outline the diagnostic procedure for this disease. Respiratory symptoms were present in all the 11 patients and the occurrence of unilateral pleural effusion (PE) was noted in 4 patients. The mean percentage of eosinophils in PE was identified to be 22.4% (range, 12.4–50.5%). In PE, lactate dehydrogenase, adenosine deaminase, proteins and carcinoembryonic antigen were detected to be 246.0 U/L, 13.8 U/L, 42.6 g/dl and 2.17 mg/mL, respectively. Experts found that parasite-specific IgG antibody in blood and parasite eggs in stool were both negative. Pleural biopsy showed no evidence of tuberculosis or malignancy. Glucocorticoid use led to elimination of symptoms and abnormal pulmonary imaging. Experts concluded that IEPE is a diagnosis of exclusion. Inquiring complete medical, surgical and drug-related histories in patients with eosinophilic pleural effusion without an obvious cause was recommended, and a thorough work-up is crucial. Follow-up following the use of glucocorticoid until effusion resolves was also advised.