Wallace ZS, et al. - Researchers examined the clinical phenotypes of IgG4-related disease in 2 cross-sectional studies assembled by an international, multispecialty network of IgG4-RD specialists. They recognized following 4 IgG4-RD phenotypes with distinct signs: Group 1 (31%), Pancreato-Hepato-Biliary disease; Group 2 (24%), Retroperitoneal Fibrosis and/or Aortitis; Group 3 (24%), Head and Neck-Limited disease and Group 4 (22%), classic Mikulicz syndrome with systemic involvement. They noticed a higher median serum IgG4 concentration (1170 mg/dL) among subjects in Group 4 as compared to groups 1–3 (316, 178 and 445 mg/dL, respectively). These phenotypes helped as a framework to classify IgG4-RD and in investigating the etiology as well as optimal treatment.