Characteristics of autoimmune pancreatitis based on serum IgG4 level

Background: Autoimmune pancreatitis is categorized as an IgG4-related autoimmune disease, mostly associated with serological alterations, however characteristics of autoimmune pancreatitis based on serum markers have not been fully evaluated. Methods: We evaluated demographics, symptoms, imaging and therapeutic outcome in 27 cases of autoimmune pancreatitis stratified by serum IgG4 level. Results: Twenty patients (74%) had elevated serum IgG4 and 7 (26%) had normal IgG4 levels. Compared to patients with normal serum IgG4 levels, patients with elevated IgG4 had higher incidence of jaundice at onset (14.3% vs. 80%, respectively; P= 0.002), more frequent diffuse pancreatic enlargement at imaging (14.3% vs. 60%, respectively; P= 0.04), significantly higher (18)F-2-fluoro-2-deoxy-D-glucose uptake of pancreatic lesions (SUV max: 4.0 vs. 5.7, respectively; P=0.02), more frequent extrapancreatic lesions (42.9% vs. 85%, respectively; P= 0.03). Response to steroids was recognized regardless of serum IgG4 level, however maintenance therapy was required more frequently amongst patients with elevated compared to normal IgG4 (85.7% vs. 33.3%, respectively; P= 0.04). Conclusions: Clinical features of autoimmune pancreatitis are different based on level of serum IgG4. Further studies are needed to clarify if normal serum IgG4 cases are a precursor of active type 1 or type 2 autoimmune pancreatitis. (C) 2011 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.