RT Journal Article SR Electronic T1 Tumor-like Chronic Pancreatitis Is Often Autoimmune Pancreatitis JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 6163 OP 6166 VO 35 IS 11 A1 SARI RÁTY A1 JUHANI SAND A1 ISTO NORDBACK A1 IRINA RINTA-KIIKKA A1 KAIJA VASAMA A1 JAANA HAGSTRÖM A1 STIG NORDLING A1 JUKKA SIRÉN A1 TUULA KIVILUOTO A1 CAJ HAGLUND YR 2015 UL http://ar.iiarjournals.org/content/35/11/6163.abstract AB Background: Distinguishing between pancreatic cancer and chronic pancreatitis (CP) is often difficult. Certain (5-6%) CP cases are autoimmune in nature, and these patients respond to corticosteroid treatment, making surgery avoidable. Our aim was to evaluate the incidence of autoimmune pancreatitis (AIP) among patients operated on for a pancreatic mass with a final histology of CP. Patients and Methods: A total of 33 patients were operated on at the Tampere or Helsinki University Hospital for suspicion of cancer, but with final histopathological diagnosis of CP. The median age was 58 (31-81) years; 26 patients (79%) were male. There were 28 pancreaticoduodenectomes and five left pancreatic resections. Surgical specimens were re-evaluated by experienced pathologists, with representative samples chosen for immunohistochemistry Each sample was scored as positive or negative for immunoglobulin G4 (IgG4) independently by two pathologists. Honolulu consensus criteria served for AIP sub-typing. Results: Out of the 33 specimens, 10 (30%) were positive for IgG4. Histopathological re-evaluation of these revealed all to be type 1 AIP. Conclusion: The proportion of AIP, according to IgG4-positive immunohistochemistry and histological re-evaluation, was much higher than expected. This suggests that by focusing on diagnosis of AIP preoperatively, certain patients might be treated with corticosteroids and possibly avoid unnecessary surgery.