IgG4 Aortitis and Periaortitis

Sites of involvement:

(1) thoracic aorta

(2) abdominal aorta

Features:

(1) variable aneurysm formation

(2) dense lymphoplasmacytic aortitis and periaortitis

(3) sclerosing/storiform fibrosis

(4) variable retroperitoneal fibrosis

(5) variable obliterative phlebitis

Evidence for IgG4:

(1) variable elevated in serum IgG4 concentrations

(2) sections of the aorta showing elevated number of IgG4 positive plasma cells with a high IgG4 to IgG ratio