Pleural fluid mesothelin for the differential diagnosis of exudative pleural effusions.

BACKGROUND Malignant mesothelioma (MM) is a highly aggressive tumor that can be difficult to diagnose, resulting in a delayed diagnosis in some cases. Recent studies have reported that determination of soluble mesothelin-related peptides (SMRP) in pleural fluid may be a promising marker for use in the diagnosis of MM. PATIENTS AND METHODS Pleural fluid SMRP concentration was measured in 68 patients: 47 had malignant pleural effusions (18 MM and 29 metastatic effusion) and 21 had benign pleural effusion (8 infectious disease and 13 idiopathic effusion). Mann-Whitney analysis was used to compare SMRP values according to the etiology of the effusion. RESULTS Pleural fluid SMRP concentration was significantly higher in patients with malignant pleural effusion than in those with benign effusion (P=0.02). When malignant pleural effusions were analyzed separately, MM patients had the highest median pleural fluid SMRP concentration, with significant differences as compared to patients with idiopathic pleural effusion. CONCLUSIONS Soluble mesothelin-related peptide measurement in pleural fluid may aid in the diagnosis of patients presenting with pleural effusion.