IgG4-related disease is becoming increasingly recognized as a cause for chronic inflammation with fibrosis and organ dysfunction. Multiple tissues may be involved. Shown here is a fibrous proliferation with infiltrates of plasma cells, typical of the inflammatory reaction that can involve multiple tissues.
The diagnosis of IgG4-RD can be made with the following 3 criteria:
If only organ involvement is present with only 1 of the remaining 2 criteria, then IgG4-RD may be considered as possible, but radiologic imaging features are needed, or... the patient responds within several weeks to a course of corticoteroid therapy. Just an increase in serum IgG4 is suggestive of IgG4-RD but is not specific.