title: Prevalence and distribution of extrapancreatic lesions complicating autoimmune pancreatitis.
abstract: BACKGROUND
  Autoimmune pancreatitis is a unique form of chronic pancreatitis characterized by high serum IgG4 concentrations and abundant IgG4-bearing plasma cell infiltration in the pancreatic lesion, and it has been reported to be associated with a variety of extrapancreatic lesions, leading us to postulate the concept of a systemic inflammatory disease. To confirm this, we clarified the exact distribution of these extrapancreatic lesions and provide a panoramic view of them.
  
  
  METHODS
  The frequency, distribution, clinical characteristics, and pathology of five extrapancreatic lesions were determined in 64 patients with autoimmune pancreatitis by examining clinical and laboratory findings.
  
  
  RESULTS
  The most frequent extrapancreatic lesion was hilar lymphadenopathy (80.4%), followed by extrapancreatic bile duct lesions (73.9%), lachrymal and salivary gland lesions (39.1%), hypothyroidism (22.2%), and retroperitoneal fibrosis (12.5%). No patients had all five types of lesions. Patients with hilar lymphadenopathy or lachrymal and salivary gland lesions were found to have significantly higher IgG4 levels than those without (P = 0.0042 and 0.0227, respectively). Patients with three lesions were found to have significantly higher IgG4 levels than those with no lesion, suggesting that patients with multiple extrapancreatic lesions have active disease. Similar to pancreatic lesions, extrapancreatic lesions have a characteristic histological finding of abundant IgG4-bearing plasma cell infiltration, and they respond favorably to corticosteroid therapy.
  
  
  CONCLUSIONS
  Autoimmune pancreatitis was recognized as a systemic inflammatory disease. Furthermore, recognition of these characteristic findings will aid in the correct diagnosis of this disease.
authors.affiliation: Department of Medicine, Gastroenterology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Hamano
authors.forename: Norikazu
authors.initials: N
authors.lastname: Arakura
authors.forename: Takashi
authors.initials: T
authors.lastname: Muraki
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Ozaki
authors.forename: Kendo
authors.initials: K
authors.lastname: Kiyosawa
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Kawa
mesh_terms: D000328:Adult; D000368:Aged; D001327:Autoimmune Diseases / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D017734:Bile Ducts, Extrahepatic / Q000473:pathology; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000453:epidemiology; D007074:Immunoglobulin G / Q000097:blood; D008206:Lymphatic Diseases / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D050500:Pancreatitis, Chronic / Q000097:blood / Q000150:complications* / Q000276:immunology / Q000503:physiopathology; D015995:Prevalence; D012185:Retroperitoneal Fibrosis / Q000453:epidemiology; D012466:Salivary Gland Diseases / Q000453:epidemiology
chemical_list: D007074:Immunoglobulin G