title: Autoimmune pancreatitis: current diagnostic criteria are suboptimal.
abstract: OBJECTIVE
  The preoperative diagnosis of autoimmune pancreatitis (AIP) is difficult, given its similar clinical presentation to pancreatic cancer. The aims of the study are to describe our center's experience with AIP and apply the Japanese AIP diagnostic criteria to a cohort of patients with histologically-proven AIP in order to assess their performance characteristics.
  
  
  METHODS
  A prospective pathology database was queried for AIP patients who were evaluated and/or treated at Johns Hopkins Hospital from 2002 to 2009. AIP histology was defined by the presence of lymphoplasmacytic infiltration, periductal inflammation, fibrosis, and periphlebitis. Imaging, clinical, and biochemical data were analyzed.
  
  
  RESULTS
  Thirty patients had pancreatic resection with pathological confirmation of AIP. Imaging revealed pancreatic mass (45%), focal prominence without mass lesion (24%), diffuse enlargement (17%), and normal pancreas (14%). Twenty-four patients underwent an endoscopic retrograde cholangiopancreatography and/or magnetic resonance cholangiopancreatography, and 4/24 (17%) had pancreatic ductal narrowing or irregularity. Extrapancreaticobiliary organ involvement was found in 6% (n = 2) of patients. Biliary strictures were present in 87% of patients. Of 16 patients who underwent preoperative tissue biopsy, 10 had non-diagnostic pathology, five had cellular atypia, and one had AIP. Serum immunoglobulin G4 (IgG4) levels were elevated in 12 of 29 (41%) patients. Three (10%) patients had evidence of extrapancreatic manifestations of AIP. When applying the Japanese criteria to the 27 patients who had serum IgG4 measurement, preoperative biopsy, and cross-sectional abdominal imaging, only 44% of the patients would have been diagnosed accurately.
  
  
  CONCLUSIONS
  When applied to a highly-selected single-center referral population in the USA, current Japanese guidelines for the diagnosis of AIP are found to have suboptimal sensitivity.
authors.affiliation: Department of Medicine and Division of Gastroenterology and Hepatology, The Sol Goldman Pancreatic Cancer Research Center, The Johns Hopkins Medical Institutions, Baltimore, Maryland, USA. samgiday@gmail.com
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Giday
authors.forename: Mouen A
authors.initials: MA
authors.lastname: Khashab
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Buscaglia
authors.forename: Devi Mukkai
authors.initials: DM
authors.lastname: Krishnamurty
authors.forename: Terina
authors.initials: T
authors.lastname: Chen
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Kalloo
authors.forename: Marcia I
authors.initials: MI
authors.lastname: Canto
authors.forename: Patrick I
authors.initials: PI
authors.lastname: Okolo
authors.forename: Ralph H
authors.initials: RH
authors.lastname: Hruban
authors.forename: Sanjay B
authors.initials: SB
authors.lastname: Jagannath
mesh_terms: D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology / Q000601:surgery; D015142:Baltimore; D015415:Biomarkers / Q000097:blood; D001706:Biopsy; D002760:Cholangiopancreatography, Endoscopic Retrograde; D049448:Cholangiopancreatography, Magnetic Resonance; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D010195:Pancreatitis / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology / Q000601:surgery; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; D007074:Immunoglobulin G