Fig. 1

Classification of IgG4-related periaortitis/periarteritis distribution into five types. Type 1 localized at the infra-renal artery portion of the abdominal aorta (16 cases; 24.6%); Type 2 added continuation to medium-sized arteries, mainly the iliac arteries (29 cases; 44.6%); Type 3 added separate localization to the ascending aorta (eight cases; 12.3%); Type 4 affected medium-sized arteries only (six cases; 9.2%); and Type 5 was other involvement