Background Autoimmune pancreatitis (AIP) has been classified into type 1 and type 2
subtypes. Serum immunoglobulin G4 (IgG4) elevation characterizes type 1 AIP. Type 2 AIP
and a subset of type 1 AIP are seronegative, ie, have normal serum IgG4 levels. Aim We
compared the profiles of the three subsets of AIP to identify the unique characteristics of
seronegative type 1 AIP and type 2 AIP. Methods We compared the clinical profiles of 69
seropositive type 1 AIP patients, 21 seronegative type 1 AIP patients and 22 type 2 AIP …