MSLN and Pleural effusion: Fibulin-3 was first studied as a biomarker of MM by Pass et al. who reported that plasma fibulin-3 levels can distinguish a healthy person with exposure to asbestos from patients with MM.13 They found that in conjunction with fibulin-3 levels in pleural effusions, plasma fibulin-3 levels can further differentiate MM effusion from other malignant and benign effusions.13 Recent studies identified soluble mesothelin as a superior diagnostic biomarker for MM compared to fibulin-3, whereas fibulin-3 provided superior prognostic information compared to mesothelin.26