title: Characteristics of autoimmune pancreatitis based on serum IgG4 level.
abstract: 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 18F-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.
authors.affiliation: Division of Endoscopy, Shizuoka Cancer Center, Shimonagakubo, Nagaizumi, Suntogun, Shizuoka, Japan. h.matsubayashi@scchr.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsubayashi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sawai
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kimura
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Masaki
authors.initials: M
authors.lastname: Tanaka
authors.forename: Naomi
authors.initials: N
authors.lastname: Kakushima
authors.forename: Kohei
authors.initials: K
authors.lastname: Takizawa
authors.forename: Maho
authors.initials: M
authors.lastname: Kadooka
authors.forename: Toshitatsu
authors.initials: T
authors.lastname: Takao
authors.forename: Sachin
authors.initials: S
authors.lastname: Hebbar
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ono
mesh_terms: D000368:Aged; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D001323:Autoantibodies / Q000097:blood; D001327:Autoimmune Diseases / Q000175:diagnosis* / Q000276:immunology*; D015415:Biomarkers / Q000097:blood; D016009:Chi-Square Distribution; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood; D007565:Jaundice / Q000209:etiology; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D010195:Pancreatitis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000276:immunology*; D049268:Positron-Emission Tomography; D011239:Prednisolone / Q000627:therapeutic use; D012008:Recurrence; D018709:Statistics, Nonparametric; D014463:Ultrasonography
chemical_list: D000893:Anti-Inflammatory Agents; D001323:Autoantibodies; D015415:Biomarkers; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D019788:Fluorodeoxyglucose F18; D011239:Prednisolone