Fig. 2

Pathological findings. a: Macroscopic observation shows that the dura surface was red and edematous, and very fragile. b: The photomicrograph shows that the solid lesion consisted of proliferated fibroblast cells and infiltrated mononuclear cells, including predominantly plasma cells, with abundant collagenous tissue (H&E; original magnification, × 400). c and d: IgG(C) and IgG4(D) staining revealed that most of the plasma cell infiltration into sclerosing lesions were IgG positive (IgG4-positive plasma cell/high power field, 60), and the ratio of IgG4-positive plasma cells (arrow) to the overall IgG-positive cells (arrow) is greater than 50% in the area containing the highest infiltration of plasma cells (original magnification, × 400) (H&E, hematoxylin and eosin; IgG, immunoglobulin G)