Brief Article
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World J Gastroenterol. Jul 7, 2013; 19(25): 4031-4038
Published online Jul 7, 2013. doi: 10.3748/wjg.v19.i25.4031
Clinical and pathological differences between serum immunoglobulin G4-positive and -negative type 1 autoimmune pancreatitis
Woo Hyun Paik, Ji Kon Ryu, Jin Myung Park, Byeong Jun Song, Joo Kyung Park, Yong-Tae Kim, Kyoungbun Lee
Woo Hyun Paik, Ji Kon Ryu, Jin Myung Park, Byeong Jun Song, Joo Kyung Park, Yong-Tae Kim, Department of Internal Medicine, Liver Research Institute, Seoul 110-744, South Korea
Ji Kon Ryu, Division of Gastroenterology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744, South Korea
Kyoungbun Lee, Department of Pathology, Seoul National University College of Medicine, Seoul 110-744, South Korea
Author contributions: All authors were involved in recruitment of patients and diagnosis of autoimmune pancreatitis; Paik WH and Park JM performed the research and wrote the paper; Ryu JK designed the research, analyzed the data and contributed to the preparation, editing, and final approval of the manuscript; Park JK and Song BJ wrote the paper; Kim YT contributed to the preparation and final approval of the manuscript and conceived the project; Lee KB was involved in re-evaluation of the histology.
Correspondence to: Ji Kon Ryu, MD, PhD, Associate Professor, Division of Gastroenterology, Department of Internal Medicine, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 110-744, South Korea. jkryu@snu.ac.kr
Telephone: +82-2-20721962 Fax: +82-2-7436701
Received: February 17, 2013
Revised: April 1, 2013
Accepted: April 18, 2013
Published online: July 7, 2013
Abstract

AIM: To identify clinical and pathological differences between serum immunoglobulin G4 (IgG4)-positive (SIP) and IgG4-negative (SIN) type 1 autoimmune pancreatitis (AIP) in South Korea.

METHODS: AIP was diagnosed by the international consensus diagnostic criteria. The medical records and pathology were retrospectively reviewed and IgG4-positive cells were counted in a high power field (HPF). Type I AIP was defined as a high serum level of IgG4 or histological finding. SIN type 1 AIP was defined as a histological evidence of type 1 AIP and a normal serum IgG4 level. The clinical and pathological findings were compared between the two groups. The analysis was performed using Student’s t test, Fischer’s exact test and Mann-Whitney’s U test. A P value of < 0.05 was considered statistically significant. As repeated comparison was made, P values of less than 5% (P < 0.05) were considered significant.

RESULTS: Twenty five patients with definite type 1 AIP (19 histologically and six serologically diagnosed cases) were enrolled. The mean tissue IgG4 concentrations were significantly higher in SIP than SIN group (40 cells per HPF vs 18 cells per HPF, P = 0.02). Among eight SIN patients, the tissue IgG4 concentrations were less than 15 cells per HPF in most of cases, except one. The sensitivity of serum IgG4 was 68% (17 SIP and eight SIN AIP). Other organ involvement was more frequently associated with SIP than SIN AIP (59% vs 26%, P = 0.016). However, the relapse rate and diffuse swelling of the pancreas were not associated with serum IgG4 level. The concentrations of IgG4-positive cells per HPF were higher in SIP than SIN AIP (40 vs 18, P = 0.02).

CONCLUSION: The sensitivity of serum IgG4 was 68% in type 1 AIP. High serum IgG4 level was associated with other organ involvement and tissue IgG4 concentration but did not affect the relapse rate in type 1 AIP.

Keywords: Autoimmunity, Chronic pancreatitis, Immunoglobulin G4-related systemic disease, Lymphoplasmacytic sclerosing pancreatitis, Immunoglobulin G4

Core tip: Type 1 autoimmune pancreatitis (AIP) is one of the immunoglobulin G4 (IgG4)-related diseases and serum IgG4 is known as a useful diagnostic marker. However, the sensitivity of serum IgG4 is variable. The sensitivity of serum IgG4 was not sufficient (68%) in definite type 1 AIP. The demographic findings were not different between SIP and SIN type 1 AIP, but other organ involvement was significantly more common in SIP than in SIN type 1 AIP. High serum IgG4 level was associated with other organ involvement and tissue IgG4 concentration, but did not affect the relapse rate in type 1 AIP.