Fig. 1

The inflammation and fibrosis grade of IgG4-RS. a Stage 1: marked diffuse lymphoplasmacytic infiltration. Lymphoid follicles have developed. Fibrosis in the centers of lobules or periductal areas and atrophy of acini (H&E staining, ×100 magnification). b Stage 2: even more prominent lymphoplasmacytic infiltration, with formation of lymphoid follicles with reactive germinal centers, reduction of the parenchyma in the salivary gland, myofibroblast hyperplasia, and storiform fibrosis. Severe fibrosis in lobule centers or periductal areas as well as severe atrophy of acini, but the outline of lobules is retained (H&E, ×100). c Stage 3: destruction of the lobular architecture with marked parenchymal loss and sclerosis, the outlines of lobules are not clear. Germinal centers have degenerated and the light area is obscured (H&E, ×100). H&E hematoxylin and eosin