Enomoto Y, et al. - Given that pathological differential diagnoses of pleuroparenchymal fibroelastosis (PPFE) include usual interstitial pneumonia (UIP) and pulmonary apical cap (PAC), researchers identified specific immunostaining makers to distinguish between these diseases. Immunohistochemistry was conducted utilizing several pleural mesothelial cell-related markers, including cytokeratin-5/6, CAM5.2, WT-1, calretinin, desmin and podoplanin, for PPFE (n = 4), UIP (n = 10) and PAC (n = 3) lung sections. Results of this study suggested that the presence of podoplanin-positive myofibroblasts could be a pathological hallmark of PPFE, proposing a pathogenic process distinct from UIP though common to PAC.