Annulus of Zinn

IgG4-related disease (IgG4-RD) is a newly recognized, multiorgan, fibro-inflammatory disease characterized by mass forming lesion with dense lymphoplasmacytic infiltration with large numbers of IgG4+ plasma cells, storiform fibrosis and sometimes obliterative phlebitis. IgG4-RD was first described in 2001 by Japanese researchers in patients with autoimmune pancreatitis with high levels of serum IgG.[1, 2] IgG4-RD usually affects individuals of middle to old age, with an onset at 50–70 years, although