title: Differences between diffuse and focal autoimmune pancreatitis.
abstract: OBJECTIVE
  To investigate differences in clinical features between diffuse- and focal-type autoimmune pancreatitis (AIP).
  
  
  METHODS
  Based on radiological findings by computed tomography and/or magnetic resonance imaging, we divided 67 AIP patients into diffuse type (D type) and focal type (F type). We further divided F type into head type (H type) and body and/or tail type (B/T type) according to the location of enlargement. Finally, we classified the 67 AIP patients into three groups: D type, H type and B/T type. We compared the three types of AIP in terms of clinical, laboratory, radiological, functional and histological findings and clinical course.
  
  
  RESULTS
  There were 34 patients with D-type, 19 with H-type and 14 with B/T-type AIP. Although obstructive jaundice was frequently detected in D-type patients (88%) and H-type patients (68%), no B/T-type patients showed jaundice as an initial symptom (P < 0.001). There were no differences in frequency of abdominal pain, but acute pancreatitis was associated more frequently in B/T-type patients (36%) than in D-type patients (3%) (P = 0.017). Serum immunoglobulin G (IgG)4 levels were significantly higher in D-type patients (median 309 mg/dL) than in B/T-type patients (133.5 mg/dL) (P = 0.042). Serum amylase levels in B/T-type patients (median: 114 IU/L) were significantly greater than in H-type patients (72 IU/L) (P = 0.049). Lymphoplasmacytic sclerosing pancreatitis (LPSP) was histologically confirmed in 6 D-type, 7 H-type and 4 B/T-type patients; idiopathic duct-centric pancreatitis was observed in no patients. Marked fibrosis and abundant infiltration of CD20-positive B lymphocytes with few IgG4-positive plasma cells were detected in 2 B/T-type patients. Steroid therapy was effective in all 50 patients (31 D type, 13 H type and 6 B/T type). Although AIP relapsed during tapering or after stopping steroids in 3 D-type and 3 H-type patients, no patients relapsed in B/T type. During follow-up, radiological features of 6 B/T-type patients were not changed and 1 B/T-type patient improved naturally.
  
  
  CONCLUSIONS
  Clinical features of H-type AIP were similar to those of D-type, but B/T-type differed from D and H types. B/T-type may involve diseases other than LPSP.
authors.affiliation: Department of Internal Medicine, Tokyo Metropolitan Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Tabata
authors.forename: Terumi
authors.initials: T
authors.lastname: Kamisawa
authors.forename: Kensuke
authors.initials: K
authors.lastname: Takuma
authors.forename: Seiichi
authors.initials: S
authors.lastname: Hara
authors.forename: Sawako
authors.initials: S
authors.lastname: Kuruma
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Inaba
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001327:Autoimmune Diseases / Q000145:classification* / Q000276:immunology / Q000473:pathology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D010195:Pancreatitis / Q000145:classification* / Q000276:immunology / Q000473:pathology
chemical_list: D007074:Immunoglobulin G