IgG4-RD with PAO/PA might be a distinct spectrum of IgG4-RD, as it is characterized by prominent fibrosis, sparse lymphoplasmacytic infiltration, fewer extra-nodal germinal centers, and mildly elevated serum IgG1, IgG4, and IgE concentrations [5, 28, 34]. The gene discussed is IGHE; the disease is immunoglobulin G4-related sclerosing disease.