title: Inflammatory pseudotumors mimicking intrahepatic cholangiocarcinoma of the liver; IgG4-positivity and its clinical significance.
abstract: BACKGROUND
  Inflammatory pseudotumor (IPT) of the liver is a benign condition with a good prognosis. However, it is difficult to distinguish clinical and radiological findings of IPT from those of malignancies. The aims of this study are to determine the clinical, radiological, and pathological characteristics, particularly relating to the role of the autoimmune mechanism in the development of inflammatory pseudotumours (IPTs) of the liver, and to suggest appropriate diagnostic and therapeutic strategy.
  
  
  METHODS
  The clinical, diagnostic, and pathological characteristics including IgG4 immunohistochemical stain and follow-up data of 22 IPT patients were retrospectively analyzed.
  
  
  RESULTS
  The patients were 16 men and 6 women with a mean age of 59 years. Fifteen patients (68.2%) had associated biliary diseases. Of the 16 patients treated conservatively, the masses completely resolved in 10 patients, and reduced in size in 5 patients within the first 6 months. The remaining 6 patients were treated by surgical resection. IgG4 staining of 17 tissue samples from 22 patients were negative, most of the infiltrate being of fibrohistiocytic type, whereas 4 of 5 lymphoplasmacytic cells of dominant tumors show positive staining of IgG4. Although IgG4-related sclerosing cholangitis was mostly of lymphoplasmacytic type, other histological and clinical characteristics were similar in both types of IPTs.
  
  
  CONCLUSIONS
  IPTs of the liver can be diagnosed based on radiological and pathological findings by needle biopsy. Although the lymphoplasmacytic type of IPTs seems to correspond to IgG4-related disease, as assessed by IgG4 immunohistochemical stain, its clinical significance is unknown. Although most IPTs can be resolved with conservative therapy, surgical resection should be considered in cases of uncertain biopsy result, presumed malignant lesion, combination with other pathology, or lack of response to conservative management.
authors: Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, Keimyung University Dongsan Medical Center, 56 Dalseong-ro, Jung-gu, Daegu 700-712, Republic of Korea.
authors: Keun Soo
authors: KS
authors: Ahn
authors: Koo Jeong
authors: KJ
authors: Kang
authors: Yong Hoon
authors: YH
authors: Kim
authors: Tae Jin
authors: TJ
authors: Lim
authors: Hye Ra
authors: HR
authors: Jung
authors: Yu Na
authors: YN
authors: Kang
authors: Jung Hyeok
authors: JH
authors: Kwon
mesh_terms: D000328:Adult; D000368:Aged; D001650:Bile Duct Neoplasms / Q000175:diagnosis*; D001653:Bile Ducts, Intrahepatic; D018281:Cholangiocarcinoma / Q000175:diagnosis*; D005260:Female; D006104:Granuloma, Plasma Cell / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism*; D006644:Histiocytes / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D007074:Immunoglobulin G