Key words forehead IgG4-related disease IgG4-related skin diseases pseudolymphoma recurrence Abbreviation used: IgG4-RD (Immunoglobulin G4-related disease) Introduction Immunoglobulin G4-related disease (IgG4-RD) is a condition involving the formation of nodules or plaques comprising accumulated IgG4-producing plasma cells. The diagnostic criteria for this new disease, which was identified in Japan, were established in 2011. 1 Umehara H. Okazaki K. Masaki Y. et al.
