Figure 1.

Classification of IgG4‐SC by cholangiographic features. Type 1 IgG4‐SC is defined by a low bile duct stricture, which is most frequently associated with AIP, and corresponds with compression of the intrapancreatic bile duct by inflammation/fibrosis within the head of pancreas. Type 2 IgG4‐SC is defined by both a diffuse intrahepatic cholangiopathy and a lower common bile duct (CBD) stricture. Type 3 IgG4‐SC includes a hilar and lower CBD stricture. Type 4 IgG4‐SC is defined by hilar stricturing alone. The type determines the differential diagnosis for IgG4‐SC: type 1, pancreatic cancer, distal CCA, chronic pancreatitis; type 2, PSC and those for type 1; type 3, hilar CCA and those for type 1; and type 4, hilar CCA, which is the most difficult to differentiate. Adapted with permission from Pancreas.7 Copyright 2006, Wolters Kluwer Health.