By limiting our study population to those with high ADA levels, we were able to evaluate a larger subset of patients with high ADA than the study by Porcel et al. Our study showed that hematologic malignancies were more prevalent than TBP in pleural effusion with ADA ≥ 150 IU/L, which is lower than the 250 IU/L suggested by a prior study. This evidence concerns the gene ADA and hematologic disorder.