title: Prevalence of autoimmune pancreatitis and other benign disorders in pancreatoduodenectomy for presumed malignancy of the pancreatic head.
abstract: BACKGROUND
  Occasionally patients undergoing resection for presumed malignancy of the pancreatic head are diagnosed postoperatively with benign disease. Autoimmune pancreatitis (AIP) is a rare disease that mimics pancreatic cancer. We aimed to determine the prevalence of benign disease and AIP in patients who underwent pancreatoduodenectomy (PD) over a 9-year period, and to explore if and how surgery could have been avoided.
  
  
  METHODS
  All patients undergoing PD between 2000 and 2009 in a tertiary referral centre were analyzed retrospectively. In cancer-negative cases, postoperative diagnosis was reassessed. Preoperative index of suspicion of malignancy was scored as non-specific, suggestive, or high. In AIP patients, diagnostic criteria systems were checked.
  
  
  RESULTS
  A total of 274 PDs were performed for presumed malignancy. The prevalence of benign disease was 8.4 %, overall prevalence of AIP was 2.6 %. Based on preoperative index of suspicion of malignancy, surgery could have been avoided in 3 non-AIP patients. All AIP patients had sufficient index to justify surgery. If diagnostic criteria would have been checked; however, surgery could have been avoided in one to five AIP patients.
  
  
  CONCLUSIONS
  The prevalence of benign disease in patients who underwent PD for presumed malignancy was 8.4 %, nearly one-third attributable to AIP. Although misdiagnosis of AIP as carcinoma is a problem of limited quantitative importance, every effort to establish the correct diagnosis should be undertaken considering the major therapeutic consequences. IgG4 measurement and systematic use of diagnostic criteria systems are recommended for every candidate patient for PD when there is no histological proof of malignancy.
authors.affiliation: Department of Gastroenterology and Hepatology, Erasmus University Medical Center, PO box 2040, 3000 CA Rotterdam, The Netherlands. mvanheerde@amphia.nl
authors.forename: M J
authors.initials: MJ
authors.lastname: van Heerde
authors.forename: K
authors.initials: K
authors.lastname: Biermann
authors.forename: P E
authors.initials: PE
authors.lastname: Zondervan
authors.forename: G
authors.initials: G
authors.lastname: Kazemier
authors.forename: C H J
authors.initials: CH
authors.lastname: van Eijck
authors.forename: C
authors.initials: C
authors.lastname: Pek
authors.forename: E J
authors.initials: EJ
authors.lastname: Kuipers
authors.forename: H R
authors.initials: HR
authors.lastname: van Buuren
mesh_terms: D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000145:classification; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000175:diagnosis* / Q000601:surgery*; D016577:Pancreaticoduodenectomy; D010195:Pancreatitis / Q000175:diagnosis*
chemical_list: D007074:Immunoglobulin G