Single organ autoimmune disorders, previously known as autoimmune pancreatitis (AIP), autoimmune cholangitis, and autoimmune sclerosing cholangitis, are now considered organ-specific manifestations of systemic immunoglobulin G4-related disease (IgG4-RD). Autoimmune pancreatitis and IgG4-RD are characterized by elevated serum IgG4 antibody (Ab) levels, accumulation of IgG4-expressing plasmacytes in affected organs, and multiorgan involvement.