Patients with an inflammatory abdominal aortic aneurysm can be divided into those with an elevated serum IgG4 and those without.
Features of IgG4-related inflammatory abdominal aortic aneurysm:
(1) serum IgG4 concentration above the upper limit of normal
(2) periaortitis with an inflammatory cell infiltrate consisting of lymphocytes, plasma cells, lymphoid follicles and eosinophils
(3) plasma cells in the inflammatory cell infiltrate often IgG4 positive
(4) retroperitoneal fibrosis
(5) obliterative phlebitis (inflammatory cell infiltration resulting in venous occlusion)
Other types of IgG4-related inflammatory conditions are discussed in Chapter 22.
