We read with great interest the article by Kim et al. (1), titled “Appendiceal immunoglobulin G4-related disease mimicking appendiceal tumor or appendicitis: a case report,” that described the first report of immunoglobulin G4 (IgG4)-related disease involving appendix. The authors emphasized the significance of recognizing this relatively recent entity in the differential diagnosis for a massfo...

Immunoglobulin G4-related sclerosing disease (IgG4-RSD) is a fibroinflammatory condition that has the potential to affect nearly every organ system. Classic histological findings include storiform fibrosis and lymphoplasmacytic infiltrates of immunoglobulin G4 (IgG4)-positive plasma cells. The clinical features of IgG4-RSD may be an under-recognized disease process that can mimic other autoimmu...