title: Infiltration of peritumoural but tumour-free parenchyma with IgG4-positive plasma cells in hilar cholangiocarcinoma and pancreatic adenocarcinoma.
abstract: BACKGROUND
  Recently, new guidelines for diagnosing IgG4-associated cholangitis have been published devaluing the diagnostic significance of IgG4-positive plasma cells and steroid trials. We sought to evaluate the utility of IgG4-positive plasma cells in discriminating IgG4-associated cholangitis from hilar cholangiocarcinoma and autoimmune pancreatitis from pancreatic adenocarcinoma under conditions when malignancy is likely to be missed.
  
  
  METHODS
  Resection specimens obtained from patients with hilar cholangiocarcinoma, pancreatic adenocarcinoma or hepatocellular carcinoma were re-evaluated for IgG4-positivity. Histological analysis focussed on peritumoural but tumour-free sections. Perioperative biochemical and clinical data were reviewed.
  
  
  RESULTS
  Nineteen patients with hilar cholangiocarcinoma and 29 patients with pancreatic adenocarcinoma were eligible for histological re-evaluation. Six of 19 (32%) patients with hilar cholangiocarcinoma and 5 of 29 (17%) patients with pancreatic adenocarcinoma were IgG4-positive (≥20 IgG4-positive plasma cells per high power field). Patients with IgG4-positive hilar cholangiocarcinoma showed significantly higher levels of serum total bilirubin (3.6mg/dl vs. 1.8mg/dl; P<0.05) and serum alanine-aminotransferase (median 343U/l vs. 63U/l, P<0.05) compared to IgG4-negative patients with hilar cholangiocarcinoma.
  
  
  CONCLUSIONS
  IgG4-positive plasma cells are of limited utility especially in distinguishing hilar cholangiocarcinoma from IgG4-associated cholangitis even when combined with clinical parameters and may be misleading under conditions when malignancy is missed.
authors.affiliation: I. Department of Medicine, University Medical Centre Hamburg-Eppendorf, Germany. Electronic address: yazidresheq@gmx.de.
authors.forename: Yazid J
authors.initials: YJ
authors.lastname: Resheq
authors.forename: Alexander
authors.initials: A
authors.lastname: Quaas
authors.forename: Daniel
authors.initials: D
authors.lastname: von Renteln
authors.forename: Christoph
authors.initials: C
authors.lastname: Schramm
authors.forename: Ansgar W
authors.initials: AW
authors.lastname: Lohse
authors.forename: Stefan
authors.initials: S
authors.lastname: Lüth
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis*; D000368:Aged; D000410:Alanine Transaminase / Q000097:blood; D001327:Autoimmune Diseases / Q000175:diagnosis*; D001650:Bile Duct Neoplasms / Q000097:blood / Q000175:diagnosis*; D001653:Bile Ducts, Intrahepatic / Q000473:pathology*; D001663:Bilirubin / Q000097:blood; D018281:Cholangiocarcinoma / Q000097:blood / Q000175:diagnosis*; D002761:Cholangitis / Q000175:diagnosis* / Q000276:immunology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D010195:Pancreatitis / Q000175:diagnosis* / Q000276:immunology; D010950:Plasma Cells / Q000737:chemistry
chemical_list: D007074:Immunoglobulin G; D000410:Alanine Transaminase; D001663:Bilirubin
keywords: Autoimmune pancreatitis; IgG4; IgG4-associated cholangitis; Malignancy