title: Isolated IgG4-related sclerosing cholangitis misdiagnosed as malignancy in an area with endemic cholangiocarcinoma: a case report.
abstract: BACKGROUND
  The most common cause of perihilar obstruction is cholangiocarcinoma, especially in Thailand. Benign perihilar stricture represents less than 20% of cases. IgG4-related disease and IgG4-related sclerosing cholangitis, however, have been receiving increased recognition. Isolated IgG4-related sclerosing cholangitis is less common. The preoperative diagnosis of IgG4-related sclerosing cholangitis without pancreatic involvement is very difficult because the clinical presentation and preoperative evaluation are extremely difficult to distinguish from perihilar cholangiocarcinoma.
  
  
  METHODS
  We report the case of a 56-year-old man who presented with obstructive jaundice with preoperative imaging showing proximal common bile duct obstruction. He underwent right lobe liver hepatectomy with extrahepatic bile duct resection and regional lymph node dissection due to high suspicion of malignancy. The pathological report showed severe acute and chronic inflammation of the bile duct with morphology and immunohistochemistry suggestive of IgG4-related sclerosing cholangitis.
  
  
  CONCLUSIONS
  IgG4-related sclerosing cholangitis with perihilar obstruction should be considered even in areas where cholangiocarcinoma is endemic.
authors.affiliation: Department of Surgery, Ramathibodi Hospital, Mahidol University, Bangkok, 10400, Thailand. narongsak.run@mahidol.ac.th.
authors.forename: Narongsak
authors.identifier: http://orcid.org/0000-0003-3522-5800
authors.initials: N
authors.lastname: Rungsakulkij
authors.affiliation: Department of Pathology, Ramathibodi Hospital, Mahidol University, Bangkok, 10400, Thailand.
authors.forename: Pattana
authors.initials: P
authors.lastname: Sornmayura
authors.affiliation: Department of Radiology, Ramathibodi Hospital, Mahidol University, Bangkok, 10400, Thailand.
authors.forename: Penampai
authors.initials: P
authors.lastname: Tannaphai
mesh_terms: D001650:Bile Duct Neoplasms / Q000175:diagnosis*; D017734:Bile Ducts, Extrahepatic / Q000473:pathology; D018281:Cholangiocarcinoma / Q000175:diagnosis*; D015209:Cholangitis, Sclerosing / Q000175:diagnosis*; D003951:Diagnostic Errors; D006498:Hepatectomy; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007249:Inflammation / Q000175:diagnosis; D041781:Jaundice, Obstructive / Q000209:etiology*; D018285:Klatskin Tumor / Q000175:diagnosis; D008297:Male; D008875:Middle Aged
chemical_list: D007074:Immunoglobulin G
keywords: Benign biliary stricture; Cholangiocarcinoma; IgG4, IgG4-related sclerosing cholangitis; Sclerosing cholangitis