Rheumatologist should be familiar with the concept of IgG4-related disease (IgG4-RD). Due to the clinical spectrum IgG4-RD can fall directly within the scope of rheumatology and are often diagnosed primarily by rheumatologists. Furthermore, IgG4RD are relevant differential diagnoses for many other rheumatic conditions. Finally, there are an increasing amount of data suggesting an important role of immunological processes observed in IgG4-RD for other rheumatic diseases.
Keywords: Differential diagnosis; Fibrosis; Periaortitis; Plasma cells; Rheumatoid arthritis.