title: IgG4-related sclerosing cholangitis in the absence of autoimmune pancreatitis mimicking extrahepatic cholangiocarcinoma.
abstract: OBJECTIVE
  IgG4-related sclerosing cholangitis in extrahepatic bile ducts in the absence of autoimmune pancreatitis (AIP) is rare and is poorly studied. Herein, we present the clinicopathological features of four cases of IgG4-related sclerosing cholangitis.
  
  
  RESULTS
  The clinicopathological features of IgG4-related sclerosing cholangitis were compared with those of IgG4-related sclerosing cholangitis with AIP (n = 7), extrahepatic cholangiocarcinoma (n = 29), primary sclerosing cholangitis (n = 40), and secondary sclerosing cholangitis (n = 12). Several histomorphologic features distinguish IgG4-related sclerosing cholangitis, including a marked degree of bile duct injury, a higher percentage of lymphoid follicle formation, a higher percentage of perineuritis, and a more diffuse and dense lymphoplasmacytic infiltrate. All four cases of IgG4-related sclerosing cholangitis occurred exclusively in males. Of these cases, none had IgG4 serology checked preoperatively, and all had a preoperative diagnosis of extrahepatic cholangiocarcinoma. Clinical follow-up was available in 2 patients with a mean time of 11 months. Follow-up confirmed the benign course of the disease as the patients showed no evidence of relapse. IgG4-related conditions, including sclerosing cholecystitis and retroperitoneal fibrosis, were noted in three patients.
  
  
  CONCLUSIONS
  IgG4-related sclerosing cholangitis in the absence of AIP presents as a distinct and under-recognized disease that mimics extrahepatic cholangiocarcinoma clinically. Awareness of this entity is essential to avoid erroneously diagnosing malignancy. The current threshold of 10 IgG4-positive plasma cells/high-power field (HPF) in the biopsy is not specific enough to exclude cholangiocarcinoma. Therefore, we suggest the diagnostic cut-off to be 50 IgG4-positive plasma cells/HPF in the biopsy.
authors: Department of Pathology and Laboratory Medicine, Indiana University School of Medicine , Indianapolis, IN , USA.
authors: Jingmei
authors: J
authors: Lin
authors: Oscar W
authors: OW
authors: Cummings
authors: Joel K
authors: JK
authors: Greenson
authors: Michael G
authors: MG
authors: House
authors: Xiuli
authors: X
authors: Liu
authors: Ilke
authors: I
authors: Nalbantoglu
authors: Rish
authors: R
authors: Pai
authors: Darell D
authors: DD
authors: Davidson
authors: Sarah A
authors: SA
authors: Reuss
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001327:Autoimmune Diseases / Q000150:complications; D001650:Bile Duct Neoplasms / Q000175:diagnosis*; D017734:Bile Ducts, Extrahepatic / Q000737:chemistry; D018281:Cholangiocarcinoma / Q000175:diagnosis*; D015209:Cholangitis, Sclerosing / Q000276:immunology* / Q000473:pathology* / Q000601:surgery; D003951:Diagnostic Errors; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D041781:Jaundice, Obstructive / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000209:etiology; D010195:Pancreatitis / Q000150:complications / Q000276:immunology; D015431:Weight Loss
chemical_list: D007074:Immunoglobulin G
keywords: IgG4-related sclerosing cholangitis; autoimmune pancreatitis; extrahepatic bile ducts; extrahepatic cholangiocarcinoma; primary sclerosing cholangitis