Peri-lobular fibrosis in the subpleural area
Subpleural fibrosis was predominantly seen in in the lateral-to-dorsal side of the bilateral lower lobes. Pleura was fibrously thickened, and fibrosis was extended along with lobular septum, making peri-lobular patterns (Figure 5ad). Masson trichrome (MT) staining revealed that the fibrosis was apparent in the band-like area (width 3-4 mm) of the subpleural region (Figure 5d).