The amendment of the Clinical Diagnostic Criteria in Japan (JPS2011) in response to the proposal of the International Consensus of Diagnostic Criteria (ICDC) for autoimmune pancreatitis

New insights into predictors of autoimmune pancreatitis relapse after steroid therapy

OBJECTIVES

While autoimmune pancreatitis (AIP) responds well to steroid therapy, the high relapse rate in type 1 AIP remains a critical problem. The present study examined predictors of relapse of type 1 AIP following steroid therapy.

MATERIALS AND METHODS

Nine factors potentially predictive of relapse were analyzed in 81 AIP patients receiving steroid therapy with follow-up ≥ 12 months. The rate of serum IgG4 decrease following steroid therapy was calculated by dividing the difference between serum IgG4 values before and at two months after the start of steroid by the IgG4 value before steroid.

RESULTS

A relapse occurred in 11 patients (13.5%) during a median of 38 months. Multivariate analysis revealed that the presence of IgG4-related retroperitoneal fibrosis (HR: 5.59; 95% CI: 1.42-22.0; p = 0.014) and the low rate of serum IgG4 decrease after steroid therapy (HR: 0.048; 95% CI: 0.005-0.46; p = 0.008) were significant, independent predictors of AIP relapse. The cut-off value based on receiver operating characteristic curve data for the rate of serum IgG4 decrease before and at two months after steroid therapy distinguishing patients with and without a relapse was 0.65. Using this cut-off value, the area under the curve, sensitivity, and specificity were found to be 0.63, 0.73, and 0.60, respectively.

CONCLUSION

The low rate of serum IgG4 decrease after the start of steroid therapy and the presence of IgG4-related retroperitoneal fibrosis were predictive of type 1 AIP relapse. Cautious, gradual tapering of steroid dosage and longer maintenance therapy are recommended for patients with these factors.

Autoimmune pancreatitis: A bibliometric analysis from 2002 to 2022

Background/Objectives

Autoimmune pancreatitis (AIP) is a distinct form of pancreatic inflammatory disease that responds well to glucocorticoid therapy. Knowledge on AIP has rapidly evolved over the past two decades. Based on bibliometric analysis, this study aimed to assess the research status of AIP over the past two decades and determine the research focus and emerging topics.

Methods

AIP-related publications published between January 1, 2002, and June 6, 2022, were retrieved from the Web of Science Core Collection. Bibliometric data were analyzed using HisCite, VOSviewer, CiteSpace, and bibliometrix package. Annual output, leading countries/regions, active institutions and authors, core journals and references, and keywords of AIP were evaluated.

Results

Overall, 1,772 publications were retrieved from 501 journals by 6,767 authors from 63 countries/regions. Japan published articles on AIP the most (n=728, 41.1%), followed by the United States (n=336, 19%), Germany (n=147, 8.3%), China (n=127, 7%), and Italy (n=107, 6%). The top three most prolific authors were Terumi Kamisawa from Tokyo Metropolitan Komagome Hospital (n=117), Kazuichi Okazaki from Kansai Medical University (n=103), and Shigeyuki Kawa from Matsumoto Dental University (n=94). Pancreas was the most productive journal regarding AIP research (n=95), followed by the Journal of Gastroenterology (n=67), Internal Medicine (n=66), Pancreatology (n=63), and World Journal of Gastroenterology (n=62). "Diagnosis" was the most mentioned keyword. "Risk," "malignancy," "outcome," "22-gauge needle," and "fine-needle aspiration" were recognized as emerging topics.

Conclusion

Japan was the leading country in AIP research. Research papers were mainly published in specialized journals. Diagnosis was the research focus. Long-term outcomes and pancreatic tissue acquisition were recognized as research frontiers for AIP.

Recent advances in the management of autoimmune pancreatitis in the era of artificial intelligence

Autoimmune pancreatitis (AIP) is a type of immune-mediated pancreatitis subdivided into two subtypes, type 1 and type 2 AIP. Furthermore, type 1 AIP is considered to be the pancreatic manifestation of the immunoglobulin G4 (IgG4)-related disease. Nowadays, AIP is increasingly researched and recognized, although its diagnosis represents a challenge for several reasons: False positive ultrasound-guided cytological samples for a neoplastic process, difficult to interpret levels of IgG4, the absence of biological markers to diagnose type 2 AIP, and the challenging clinical identification of atypical forms. Furthermore, 60% and 78% of type 1 and type 2 AIP, respectively, are retrospectively diagnosed on surgical specimens of resected pancreas for suspected cancer. As distinguishing AIP from pancreatic ductal adenocarcinoma can be challenging, obtaining a definitive diagnosis can therefore prove difficult, since endoscopic ultrasound fine-needle aspiration or biopsy of the pancreas are suboptimal. This paper focuses on recent innovations in the management of AIP with regard to the use of artificial intelligence, new serum markers, and new therapeutic approaches, while it also outlines the current management recommendations. A better knowledge of AIP can reduce the recourse to surgery and avoid its overuse, although such an approach requires close collaboration between gastroenterologists, surgeons and radiologists. Better knowledge on AIP and IgG4-related disease remains necessary to diagnose and manage patients.

Optimal target b-value on computed diffusion-weighted magnetic resonance imaging for visualization of pancreatic ductal adenocarcinoma and focal autoimmune pancreatitis

PURPOSE

To compare computed diffusion-weighted imaging (cDWI) feasibility with that of directly acquired DWI for visualizing pancreatic ductal adenocarcinoma (PDAC) and focal autoimmune pancreatitis (AIP).

METHODS

From April 2012 to January 2017, 135 patients with PDAC (n = 111) or focal AIP (n = 24) were retrospectively enrolled. They underwent DWI with b-values of 0, 500, and 1000 s/mm². From DWI₀ and DWI₁₀₀₀, we generated cDWIs with targeted b-values of 1500, 2000, and 3000 s/mm². The lesions' signal intensities, image quality, signal intensity ratio (SIR) of lesions and pancreatic parenchyma to spinal cord, and lesion-to-pancreatic parenchyma contrast ratio (CR) were compared among the five DWI protocols (DWI₅₀₀, DWI₁₀₀₀, cDWI₁₅₀₀, cDWI₂₀₀₀, and cDWI₃₀₀₀). SIR was analyzed by receiver operating characteristic (ROC) analyses.

RESULTS

DWI₅₀₀, DWI₁₀₀₀, and cDWI₁₅₀₀ had higher image quality than cDWI₂₀₀₀ and cDWI₃₀₀₀ (P < 0.001). The incidence of clear hyperintense PDAC was highest on cDWI₂₀₀₀, followed by cDWI₁₅₀₀, and cDWI₃₀₀₀ (P < 0.001-0.002), while the incidence of clear hyperintense AIP was higher on DWI₁₀₀₀, cDWI₁₅₀₀, and cDWI₂₀₀₀ than on DWI₅₀₀ and cDWI₃₀₀₀ (P = 0.001-0.022). SIRs decreased whereas CRs increased as the b-value increased, for both PDAC and AIP. The area under the ROC curve (AUC) of SIR_lesion was significantly lower on cDWI₁₅₀₀ than on cDWI₂₀₀₀ and cDWI₃₀₀₀ (P < 0.001).

CONCLUSION

cDWI₁₅₀₀ or cDWI₂₀₀₀ generated from b-values of 0 and 1000 s/mm² were the most effective for visualizing PDAC and focal AIP; however, the SIR_lesion AUC was significantly lower on cDWI₁₅₀₀ than on cDWI₂₀₀₀ and cDWI₃₀₀₀.

Autoimmune pancreatitis: Current perspectives

Over the last two decades, our knowledge and understanding regarding the pathogenesis and biology of autoimmune pancreatitis (AIP) have improved tremendously. Type 1 AIP or IgG4-related pancreatitis (IgG4-RP) is now believed to be the prototype of the multisystemic IgG4-related disease. In view of clinical features like obstructive jaundice and mass-forming lesions in the pancreas in elderly men, type 1 AIP often mimics pancreatic cancer. IgG4-related sclerosing cholangitis concomitantly involving the extrahepatic and intrahepatic biliary tree is the most common extrapancreatic involvement seen in up to 80% of these patients, which needs to distinguish from cholangiocarcinoma. Histology is characterised by lymphoplasmacytic inflammation, abundant IgG4 positive plasma cell infiltration, storiform fibrosis and obliterative phlebitis. Apart from histology, high serum IgG4 levels, pancreatic parenchymal and duct imaging findings and other organ involvement aid in diagnosis especially in cases where definitive histology is not evident. Also, these parameters lay the foundation of various diagnostic criteria proposed over last few years. On the contrary, histology alone is the mainstay for establishing diagnosis of idiopathic duct-centric pancreatitis (IDCP) as it lacks any specific serological marker or imaging. Since both types of AIP respond dramatically to corticosteroid treatment, a biopsy is crucial to establish the preoperative diagnosis and to exclude malignancy so as to avoid unnecessary surgery. This review discusses the morphologic spectrum, treatment and prognosis of IgG4-RP and IDCP with an emphasis on approach to diagnosis with relevant histologic features, differential diagnoses and the challenges faced during biopsy interpretation.

Efficacy and limitations of the histological diagnosis of type 1 autoimmune pancreatitis with endoscopic ultrasound-guided fine needle biopsy with large tissue amounts

OBJECTIVES

We examined the efficacy and limitations of acquiring large specimens by endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) for diagnosing type 1 autoimmune pancreatitis (AIP).

METHODS

Patients from 12 institutions with non-neoplastic diseases or pancreatic ductal adenocarcinoma (PDAC) with large EUS-FNB specimens were investigated. Slides stained with hematoxylin-eosin, elastic, IgG4, and IgG stains were evaluated. The IgG4- and IgG-positive cell numbers were counted in three foci. The diagnoses were based on the Japan Pancreas Society 2011 (JPS 2011) criteria and the International Consensus Diagnostic Criteria (ICDC).

RESULTS

We analyzed 85 non-neoplastic (definite type 1 AIP in 73/85 based on the ICDC) cases and 64 PDAC cases. IgG4-positive cells were numerous (>10 in 85.9%), and the IgG4/IgG ratios were high (>40% in 81.2%). Plasma cell crushing by an artifact caused unsuccessful immunostaining, notably in smaller samples. Tissue lengths were an important factor for the presence of storiform fibrosis and obliterative phlebitis, but storiform fibrosis was equivocal even in large tissues. A definite or possible histological diagnosis was achieved in 45.9% (39/85) and 41.2% (35/85), respectively, and contributed to the definite final diagnosis of type 1 AIP in 33.3% (ICDC) and 55.6% (JPS 2011) in cases with segmental/focal lesions. In the PDAC group, >10 IgG4-positive cells was rare (2/58), but elastic stains revealed fibrous venous occlusions in 10.3% (6/58).

CONCLUSIONS

EUS-FNB with large tissue amounts was useful for diagnosing type 1 AIP, notably by facilitating successful IgG4 immunostaining, but definite diagnosis may not be achieved even in cases with large specimens.

Does IgG4 level evaluation in pancreatic mass play role in avoiding major surgery in uncertain presentation: A case report

A 66-year-old male presented with chief complaints of anorexia associated with mild dull, intermittent epigastric pain for 6 months. The patient was a known diabetic on oral hypoglycemic and on routine checkup was found to have deranged liver function profile. On radiology, an ill-defined hypoechoic enhancing lesion involving head, neck, and uncinate process of pancreas was noted. Whipple's pancreaticodudenectomy was done and reported as IgG4-related autoimmune pancreatitis. Later, IgG (slightly) and IgG4 were found to be markedly raised. We report this case to highlight the importance of IgG4 evaluation prior to major surgery in uncertain pancreatic mass.

Japanese Clinical Diagnostic Criteria for Autoimmune Pancreatitis, 2018: Revision of Japanese Clinical Diagnostic Criteria for Autoimmune Pancreatitis, 2011

Supplemental digital content is available in the text.

Autoimmune Pancreatitis and IgG4-Related Disease: The Storiform Discovery to Treatment

Autoimmune pancreatitis (AIP) is an entity that has been recognized since 1961. Prior to the discovery of elevated serum IgG4 as a useful biomarker for its diagnosis, Dr. Yoshida in 1995 first described the entity of AIP, which in retrospect closely resembles the current concept of type 1 AIP. Since the discovery of IgG4 as a biomarker (the IgG4-era), a novel concept of IgG4-related disease (IgG4-RD) has been accepted as being comprised of two subtypes of AIP: type 1 defined as the pancreatic manifestation of IgG4-RD, and type 2 characterized by granulocytic epithelial lesions. The characteristic features of type 1 AIP are increased serum IgG4 levels, lymphoplasmacytic sclerosing pancreatitis (abundant infiltration of IgG4+ plasmocytes and lymphocytes, storiform fibrosis, and obliterative phlebitis), extrapancreatic manifestations of IgG4-RD (e.g., sclerosing cholangitis, sclerosing sialadenitis, retroperitoneal fibrosis), and steroid responsiveness. These entities can be differentiated from mimickers by a combination of serum IgG4 level, imaging features, and histopathological findings. The current first-line therapy is corticosteroids, or rituximab in high-risk patients with steroid intolerance. Although relapse rates are high, treatment of relapsed disease remains experimental.

Predictive Factors for Autoimmune Pancreatitis Relapse After 3 Years of Maintenance Therapy

OBJECTIVES

Oral corticosteroid treatment is the standard therapy for autoimmune pancreatitis (AIP) and is highly effective. However, relapse may occur during maintenance therapy (MT). We aimed to clarify the predictive factors for relapse after 3 years of MT for use in deciding on the continuation of long-term MT.

METHODS

Among 56 retrospectively recruited AIP patients who received corticosteroid remission induction therapy followed by MT for a minimum of 5 years, 38 subjects were enrolled after exclusion criteria and divided into the relapse group of patients who experienced relapse after 3 years of MT and the nonrelapse group of patients who did not.

RESULTS

According to multivariate analysis, at least 4 other organ involvement numbers at diagnosis (hazard ratio, 5.82; 95% confidence interval, 1.203-28.192) and IgG of 1400 mg/dL or greater at 3 years of MT (hazard ratio, 4.41; 95% confidence interval, 1.096-17.790) were predictive factors for relapse after MT for 3 years, with patients exhibiting both predictive factors having a higher cumulative relapse rate than those with 1 or fewer predictive factor.

CONCLUSIONS

We uncovered 2 predictive factors for AIP relapse after 3 years of MT. These findings will assist in deciding corticosteroid therapy regimens at 3 years of MT to minimize AIP relapse risk and adverse corticosteroid effects.

The use of magnetic resonance elastography in differentiating autoimmune pancreatitis from pancreatic ductal adenocarcinoma: A preliminary study

PURPOSE

To assess the value of magnetic resonance elastography (MRE) in patients with autoimmune pancreatitis (AIP) and in the differentiation of AIP from pancreatic ductal adenocarcinoma (PDAC).

METHOD AND MATERIALS

This prospective study included 14 AIP patients, 26 PDAC patients, and 14 healthy volunteers. All participants underwent pancreatic MRE (40-Hz; 3 T scanner) at enrollment, and 7 AIP patients underwent a second MRE after initiation of steroid therapy. Pancreatic stiffness values were obtained by MRE and a new logistic regression model (the calculated Rad score) was used to combine pancreatic stiffness and the distribution and shape of high-stiffness areas for differentiation of AIP and PDAC. The area under the curve (AUC) was calculated for all parameters using receiver operating characteristic (ROC) analysis.

RESULTS

Pancreatic stiffness was significantly higher (2.67 kPa [interquartile range, 2.24-3.56 kPa]) in AIP than in healthy pancreas (1.24 kPa [1.18-1.24 kPa]) and significantly lower in AIP than in PDAC (3.78 kPa [3.22-5.11 kPa]; both P < 0.05). Diffuse (n = 4 vs 1; P = 0.043) and multiple (n = 3 vs 0; P = 0.037) lesions were more common in AIP, while solitary (n = 25 vs 7; P = 0.001) and nodular lesions (n = 18 vs 2; P =  0.002) were more frequent in PDAC. Rad scores outperformed individual imaging parameters in distinguishing AIP from PDAC (AUC, 0.948 vs 0.607 to 0.782; all P < 0.05), with 84.6% specificity and 92.9% sensitivity. Pancreatic stiffness in AIP decreased significantly, from 2.66 kPa [2.29 to 3.05 kPa] to 1.55 kPa [1.43 to 1.67 kPa] (P = 0.016), during treatment.

CONCLUSIONS

MRE shows promise as a quantitative imaging method for differentiating AIP from PDAC and for monitoring the treatment response in AIP.

Hypothyroidism in patients with autoimmune pancreatitis

AIM

To examine thyroid function and clinical features of hypothyroidism in autoimmune pancreatitis (AIP) patients.

METHODS

We examined thyroid function in 77 patients with type 1 AIP (50 males, 27 females; median age 68 years, range 33-85) diagnosed according to the Japanese diagnostic criteria for AIP 2011. We compared clinical and serological findings between patients with and without various categories of hypothyroidism. The change in hypothyroidism after steroid therapy was also examined.

RESULTS

Eight patients (10%) had hypothyroidism of 6 patients had subclinical hypothyroidism with a normal serum free thyroxine (FT4) and high thyroid stimulating hormone (TSH) level, and 2 patients had central hypothyroidism with low serum free triiodothyronine (FT3), FT4 and TSH levels. A significant goiter of the thyroid was not observed in any patient. There were no significant differences in age; male to female ratio; serum concentrations of IgG and IgG4-related disease (IgG4-RD); presence of anti-thyroglobulin antibody, antinuclear antigen or rheumatoid factor; or presence of extrapancreatic lesions between the 6 patients with subclinical hypothyroidism and patients with euthyroidism. After steroid therapy, both subclinical and central hypothyroidism improved with improvement of the AIP.

CONCLUSION

Hypothyroidism was observed in 8 (10%) of 77 AIP patients and was subclinical in 6 patients and central in 2 patients. Further studies are necessary to clarify whether this subclinical hypothyroidism is another manifestation of IgG4-RD.

Serum apolipoprotein A2 isoforms in autoimmune pancreatitis

Recently, apolipoprotein A2 (apoA2) isoforms have been reported as candidate serum/plasma biomarkers of pancreatic cancer. However, the distribution of apoA2 isoforms in patients with autoimmune pancreatitis (AIP) has not been investigated yet. In this study, we evaluated the distribution of serum apoA2 isoforms; i.e., homodimer apoA2-ATQ/ATQ, heterodimer apoA2-ATQ/AT, and homodimer apoA2-AT/AT, in AIP patients and healthy volunteers (HV) using enzyme-linked immunosorbent assays, and the clinical characteristics and serum levels of each apoA2 isoform in 32 AIP patients and 38 HV were investigated. The calculated apoA2-ATQ/AT levels of the AIP patients were significantly lower than those of the HV, which agreed with results obtained for patients with pancreatic cancer. Interestingly, most of the AIP patients exhibited high levels of apoA2-ATQ along with low levels of apoA2-AT, indicating that the processing of the C-terminal regions of apoA2 dimer was inhibited in the AIP patients. This specific distribution of serum apoA2 isoforms might provide important information about the disease states of AIP patients and aid the differential diagnosis of AIP versus pancreatic cancer.

Diagnosing autoimmune pancreatitis with the Unifying-Autoimmune-Pancreatitis-Criteria

BACKGROUND/OBJECTIVES

We had developed the Unifying-Autoimmune-Pancreatitis-Criteria (U-AIP) to diagnose autoimmune pancreatitis (AiP) within the M-ANNHEIM classification of chronic pancreatitis. In 2011, International-Consensus-Diagnostic-Criteria (ICDC) to diagnose AiP have been published. We had applied the U-AIP long before the ICDC were available. The aims of the study were, first, to describe patients with AiP diagnosed by the U-AIP; second, to compare diagnostic accuracies of the U-AIP and other diagnostic systems; third, to evaluate the clinical applicability of the U-AIP.

METHODS

From 1998 until 2008, we identified patients with AiP using U-AIP, Japanese-, Korean-, Asian-, Mayo-HISORt-, Revised-Mayo-HISORt- and Italian-criteria. We retrospectively verified the diagnosis by ICDC and Revised-Japanese-2011-criteria, compared diagnostic accuracies of all systems and evaluated all criteria in consecutive patients with pancreatitis (2009 until 2010, Pancreas-Outpatient-Clinic-Cohort, n = 84). We retrospectively validated our diagnostic approach in consecutive patients with a pancreatic lesion requiring surgery (Surgical-Cohort, n = 98).

RESULTS

Overall, we identified 21 patients with AiP. Unifying-Autoimmune-Pancreatitis-Criteria and ICDC presented the highest diagnostic accuracies (each 98.8%), highest Youden indices (each 0.95238), and highest proportions of diagnosed patients (each n = 20/21, U-AIP/ICDC vs. other diagnostic systems, p < 0.05, McNemar test). In the Pancreas-Outpatient-Clinic-Cohort, seven patients were diagnosed with AiP (n = 6 by U-AIP, n = 1 by Asian-criteria). International-Consensus-Diagnostic-Criteria confirmed the diagnosis in these individuals. Based on partial fulfillment of U-AIP, AiP was initially suspected in 13% (n = 10/77) of remaining patients from the Pancreas-Outpatient-Clinic-Cohort. In the Surgical-cohort, we identified one patient with AiP by U-AIP and ICDC.

CONCLUSIONS

Unifying-Autoimmune-Pancreatitis-Criteria revealed a satisfactory clinical applicability and offered an additional approach to diagnose AiP.

Serological characteristics of autoimmune pancreatitis and its differential diagnosis from pancreatic cancer by using a combination of carbohydrate antigen 19-9, globulin, eosinophils and hemoglobin

Autoimmune pancreatitis (AIP) is a special type of chronic pancreatitis, which may be misdiagnosed as pancreatic carcinoma. This study aims to verify new biomarkers for AIP and propose a serological pattern to differentiate AIP from pancreatic adenocarcinoma with routinely performed tests. In this study, data of serum samples were collected and compared between 25 patients with AIP and 100 patients with pancreatic carcinoma. Receiver operating characteristic analysis and logistic regression was performed to evaluate the diagnostic effect of serum parameters in differentiating AIP from pancreatic carcinoma alone or in combination. Among several serum markers observed in the two groups, carbohydrate antigen 19-9 (Ca19-9), globulin, eosinophils and hemoglobin were selected as the independent markers. Serum levels of Globulin, Eosinophil percentage in AIP group were significantly higher than in pancreatic cancer group (P<0.05), while hemoglobin and tumor marker CA19-9 levels were lower (P <0.05). The combination of these markers identified patients with AIP with 92% sensitivity and 79% specificity, which indicated relatively high diagnostic value. Elevated serum eosinophils, globulin, together with decreased hemoglobin level can be used as a preoperative indicator for AIP and can help to initiate diagnosis of AIP in time.

From Pathogenesis, Clinical Manifestation, and Diagnosis to Treatment: An Overview on Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is a special type of chronic pancreatitis which is autoimmune mediated. The international consensus diagnostic criteria (ICDC) 2011 proposed two types of AIP: type I is associated with histological pattern of lymphoplasmacytic sclerosing pancreatitis (LPSP), characterized by serum IgG4 elevation, whereas type 2 is named idiopathic duct-centric pancreatitis (IDCP), with granulocytic epithelial lesion (GEL) and immunoglobulin G4 (IgG4) negative. The pathogenic mechanism is unclear now; based on genetic factors, disease specific or related antigens, innate and adaptive immunity may be involved. The most common clinical manifestations of AIP are obstructive jaundice and upper abdominal pain. The diagnosis can be made by a combination of parenchymal and ductal imaging, serum IgG4 concentrations, pancreatic histology, extrapancreatic disease, and glucocorticoid responsiveness according to ICDC 2011. Because of the clinical and imaging similarities with pancreatic cancer, general work-up should be done carefully to exclude pancreatic malignant tumor before empirical trial of glucocorticoid treatment. Glucocorticoid is the most common drug for AIP to induce remission, while there still exists controversy on steroid maintenance and treatment for relapse. Further studies should be done to identify more specific serum biomarkers for AIP, the pathogenic mechanisms, and the treatment for relapse.

A case of autoimmune pancreatitis effectively treated with an immunosuppressant (azathioprine)

The patient was a 42-year-old man who presented at our hospital with obstructive jaundice. Although antinuclear antibody test results were negative, and immunoglobulin G4 (IgG4) was not elevated, endoscopic ultrasound revealed a mixed internal hyperechoic and diffuse hypoechoic pattern, a finding consistent with autoimmune pancreatitis. Endoscopic retrograde cholangiopancreatography further revealed irregular narrowing of the main pancreatic duct and sclerosing cholangitis with distal biliary stricture. In addition, endoscopic ultrasound with fine needle aspiration cytology resulted in a diagnosis of type 1 autoimmune pancreatitis. Oral prednisolone treatment was initiated at 30 mg/day, and the dosage was gradually decreased. However, in accordance with the patient's wishes, maintenance treatment was discontinued once dosage reached 5 mg/day. Despite this, relapse of obstructive jaundice occurred 1 month post discontinuation, and was treated with methyl-prednisolone pulse therapy (500 mg/day) followed by oral prednisolone. However, computed tomography, magnetic resonance imaging, and endoscopic ultrasound did not reveal sufficient improvement after 6 months of treatment. Therefore, an immunosuppressant (azathioprine) was introduced. Subsequent imaging analyses and endoscopic ultrasound fine needle aspiration revealed clear improvements in pathology.

Correlation between long-term outcome and steroid therapy in type 1 autoimmune pancreatitis: relapse, malignancy and side effect of steroid

OBJECTIVES

Autoimmune pancreatitis (AIP) responds well to corticosteroid therapy (CST), and CST is essential to induce remission. However, the correlation between long-term outcome and CST has not been evaluated. We aimed to clarify the correlation between long-term outcome of AIP and CST.

MATERIAL AND METHODS

We retrospectively evaluated relapse, risk of malignancy and side effects of CST by focusing on the correlation with CST in 84 patients with type 1 AIP.

RESULTS

The incidence of relapse was 23.8%. The frequency of relapse after CST administration was significantly lower in patients taking CST for >6 months than in those who did not (22% versus 67%; p = 0.036). The incidence of malignancy was 10.7%. The standardized incidence ratio of malignancy was 2.14 [95% confidence interval 0.74-3.54]. There were no significant correlations between development of malignancy and CST. The incidences of total and serious side effects due to CST were 75% and 19.1%, respectively. Relapse was the only significant independent predictive risk factor for serious side effects in a multivariate analysis (odds ratio 4.065; 95% confidence interval 1.125-14.706; p = 0.032). The cumulative dose of corticosteroid was significantly higher in patients with serious side effects than in those without (12,645 mg versus 7322 mg; p = 0.041).

CONCLUSIONS

CST reduces relapse of AIP. However, CST causes serious side effects, particularly in relapsing patients. Alternative maintenance therapy to prevent relapse is needed.

Diagnostic Performance of Serum IgG4 Levels in Patients With IgG4-Related Disease

The aim of this study is to study the clinical features and diagnostic performance of IgG4 in Chinese populations with IgG4-related diseases (IgG4-RDs).The medical records of 2901 adult subjects who underwent serum IgG4 level tests conducted between December 2007 and May 2014 were reviewed.Serum concentrations of IgG4 were measured in 2901 cases, including 161 (5.6%) patients with IgG4-RD and 2740 (94.4%) patients without IgG4-RD (non-IgG4-RD group). The mean age of the IgG4-RD patients was 58.4 ± 16.1 years (range: 21-87), and 48 (29.8%) were women. The mean serum IgG4 level was significantly much higher in IgG4-RD patients than in non-IgG4-RD (1062.6 vs 104.3 mg/dL, P < 0.001) participants. For IgG4 >135 mg/dL, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), likelihood ratio (LR)+, and LR- were 86%, 77%, 18%, 99%, 3.70, and 0.19, respectively. When the upper limit of normal was doubled for an IgG4 >270 mg/dL, the corresponding data were 75%, 94%, 43%, 98%, 12.79, and 0.26, respectively. For IgG4 >405 mg/dL (tripling the upper limit of normal), the corresponding data were 62%, 98%, 68%, 98%, 37.00, and 0.39, respectively. When calculated according to the manufacturer's package insert cutoff (>201 mg/dL) for the diagnosis of IgG4-RD, the corresponding sensitivity, specificity, PPV, NPV, LR+, and LR- were 80%, 89%, 29%, 99%, 7.00, and 0.23, respectively. For IgG4 >402 mg/dL (>2× the upper limit of the normal range), the corresponding data were 62%, 98%, 68%, 98%, 36.21, and 0.39, respectively. For IgG4 >603 mg/dL (>3× the upper limit of the normal range), the corresponding data were 50%, 99%, 84%, 97%, 90.77 and 0.51, respectively. The optimal cutoff value of serum IgG4 (measured by nephelometry using a Siemens BN ProSpec instrument and Siemens reagent) for the diagnosis of IgG4-RD was 248 mg/dL, the sensitivity and specificity were 77.6% and 92.8%, respectively.The present study demonstrated that 2 or 3 times the upper limit of the manufacturer's reference range of the IgG4 level was a useful marker for the diagnosis of various types of IgG4-RD and the optimal cutoff level was 248 mg/dL.

Characteristic findings of endoscopic retrograde cholangiopancreatography in autoimmune pancreatitis

Background/Aims

Diffuse or segmental irregular narrowing of the main pancreatic duct (MPD), as observed by endoscopic retrograde cholangiopancreatography (ERCP), is a characteristic feature of autoimmune pancreatitis (AIP).

Methods

ERCP findings were retrospectively examined in 40 patients with AIP in whom irregular narrowing of the MPD was detected near the orifice. The MPD opening sign was defined as the MPD within 1.5 cm from the orifice being maintained. The distal common bile duct (CBD) sign was defined as the distal CBD within 1.5 cm from the orifice being maintained. Endoscopic findings of a swollen major papilla and histological findings of specimens obtained from the major papilla were examined in 26 and 21 patients, respectively.

Results

The MPD opening sign was detected in 26 of the 40 patients (65%). The distal CBD sign was detected in 25 of the 32 patients (78%), which showed stenosis of the lower bile duct. The patients who showed the MPD opening sign frequently showed the distal CBD sign (p=0.018). Lymphoplasmacytic infiltration, but not dense fibrosis, was histologically detected in biopsy specimens obtained from the major papilla.

Conclusions

On ERCP, the MPD and CBD adjacent to the major papilla are frequently maintained in patients with AIP involving the pancreatic head. These signs are useful for diagnosing AIP on ERCP.

Recent developments in steroid-responsive pancreatitides (autoimmune pancreatitis)

PURPOSE OF REVIEW

There are two distinct steroid responsive chronic fibro-inflammatory diseases of the pancreas, called type 1 and type 2 autoimmune pancreatitis (AIP). We review recent progress in this field.

RECENT FINDINGS

It has recently been suggested that the term AIP be used to describe type 1 AIP and the term idiopathic duct-centric chronic pancreatitis (IDCP) be used for type 2 AIP. Clinical features and long-term outcomes of AIP and IDCP are well characterized and prognosis of both diseases is excellent. Diagnostic strategies tailored to regional practice patterns have emerged with the application of International Consensus Diagnostic Criteria for AIP. Although corticosteroids remain the mainstay of treatment, management of relapses and strategies for preventing multiple relapses are better understood, including the role of maintenance therapy and B-cell depletion therapy with rituximab. Association studies with malignancies have yielded conflicting results regarding risk of cancer in AIP.

SUMMARY

The treatment, follow-up guidelines and associations continue to evolve with our increasing experience with both AIP and IDCP. In AIP, rituximab can be used for both induction and maintenance of remission. IDCP responds to steroids without need for maintenance therapy. Both AIP and IDCP have excellent prognosis.

Autoimmune pancreatitis complicated with inflammatory bowel disease and comparative study of type 1 and type 2 autoimmune pancreatitis

BACKGROUND

Two types of autoimmune pancreatitis (AIP) have been reported, lymphoplasmacytic sclerosing pancreatitis and idiopathic duct-centric chronic pancreatitis (IDCP), which are now recognized as type 1 and type 2 AIP, respectively. Since the clinical features of type 2 AIP have not been fully elucidated and this condition is frequently accompanied by inflammatory bowel disease (IBD), we performed a nationwide survey of patients with AIP complicated with IBD to precisely characterize this disease entity.

METHODS

We collected 138 cases of pancreatitis with complicating IBD from affiliated institutes specializing in AIP or IBD, and comparative study between the IDCP groups and type 1 AIP was performed.

RESULTS

Histological examination revealed 15 AIP cases to be IDCP of institutional diagnosis, among which 11 cases were upgraded to IDCP of central diagnosis by an expert pathologist. The IDCP group exhibited younger onset age, no gender bias, frequent abdominal pain, and normal IgG4 value, similar to those of type 2 AIP reported previously. We also witnessed a lower prevalence of jaundice in type 2 AIP than in type 1 AIP that corresponded to imaging findings of less frequent pancreatic head swelling and scarce bile duct stenosis.

CONCLUSIONS

A characteristic feature of type 2 AIP compared with type 1 AIP is a low frequency of obstructive jaundice that is related to rare lower bile duct stricture due to lower prevalence of pancreatic head swelling. Contrary to type 1 AIP, lower bile duct stricture in this condition has no apparent relation to sclerosing cholangitis.

Diagnosis and Treatment of Autoimmune Pancreatitis in China: A Systematic Review

AIMS

To provide comprehensive data on the diagnosis and treatment of autoimmune pancreatitis (AIP) patients in China.

DESIGN

A systematic review.

METHODS

All clinical studies concerning AIP from China published between January 2006 and June 2014 were retrospectively reviewed and analyzed.

RESULTS

A total of 26 original articles involving 706 AIP patients were included with an estimated proportion of type 2 AIP as 4.7%. In the 706 AIP patients, the range of mean/median age was 48.6-67.0 years old and the male to female ratio was 4.47:1. The common presentations included obstructive jaundice (pooled rate: 63.4%, 95%CI: 55.4%-71.0%) and abdominal symptoms (pooled rate: 62.3%, 95%CI: 52.4%-71.7%). Biliary involvement was the most common extrapancreatic manifestations, especially the lower part of the common bile duct (pooled rate: 62.3%, 95%CI: 49.9%-73.9%). According to the imaging examinations, 53.8% and 41.6% patients were classified into focal-type and diffuse-type, respectively. Notably, upstream pancreatic duct dilatation was found in parts of patients (pooled rate: 13.8%, 95%CI: 6.6%-23.1%). The levels of serum IgG4 were elevated in most patients (pooled rate: 86.0%, 95%CI: 74.2%-94.6%). Nearly three tenths AIP patients received surgery (pooled rate: 29.7%, 95%CI: 18.1%-42.8%) due to mimicked malignancy. Steroid treatment was given to 78.4% patients (95%CI: 65.3%-89.1%) with a pooled remission rate of 96.2% (95%CI: 94.0%-97.9%). The pooled relapse rate was 13.8% (95%CI: 7.2%-22.0%) with the mean follow-up time ranging from 12 to 45 months.

CONCLUSION

Type 1 is the predominant type of Chinese AIP patients and the clinical features, diagnostic modalities and therapeutic regimen were similar with those in other countries. Knowledge of AIP should be more widespread to avoid unnecessary surgery.

Nationwide epidemiological survey of autoimmune pancreatitis in Japan in 2011

OBJECTIVES

To clarify the clinicoepidemiological features of autoimmune pancreatitis (AIP) in Japan, a nationwide epidemiological survey was conducted.

METHODS

Patients with AIP who had visited selected hospitals in 2011 were surveyed. Autoimmune pancreatitis was diagnosed according to the revised clinical diagnostic criteria for AIP (Japan Pancreas Society 2011). The study consisted of 2 stage surveys; the number of patients with AIP was estimated by the first questionnaire, and their clinical features were assessed by the second questionnaire.

RESULTS

The estimated total number of AIP patients in 2011 was 5745 (95% confidence interval, 5325-6164), with an overall prevalence rate of 4.6 per 100,000 population. The number of patients who were newly diagnosed as AIP was estimated to be 1808 (95% confidence interval, 1597-2018), with an annual incidence rate of 1.4 per 100,000 population. The sex ratio (male to female) was 3.2, and the mean age was 66.3 (11.5). Among the 936 patients whose detailed clinical information was obtained, 86.4% of the patients presented high serum immunoglobulin G4 levels (≥135 mg/dL), and 82.3% received steroid therapy.

CONCLUSIONS

The data represent the current clinical features of AIP in Japan.

Endoscopic approaches for the diagnosis of autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is characterized by diffuse pancreatic enlargement and irregular narrowing of the main pancreatic duct (MPD). Immunoglobulin (Ig)G4-related sclerosing cholangitis (IgG4-SC) associated with AIP frequently appears as a bile duct stricture. Therefore, it is important to differentiate AIP and IgG4-SC from pancreatic cancer and cholangiocarcinoma or primary sclerosing cholangitis, respectively. Endoscopy plays a central role in the diagnosis of AIP and IgG4-SC because it provides imaging of the MPD and bile duct strictures as well as the ability to obtain tissue samples for histological evaluations. Diffuse irregular narrowing of MPD on endoscopic retrograde cholangiopancreatography (ERCP) is rather specific to AIP, but localized narrowing of the MPD is often difficult to differentiate from MPD stenosis caused by pancreatic cancer. A long stricture (>1/3 the length of the MPD) and lack of upstream dilatation from the stricture (<5 mm) might be key features of AIP on ERCP. Some cholangiographic features, such as segmental strictures, stric tures of the lower bile duct, and long strictures with prestenotic dilatation, are more common in IgG4-SC than in cholangiocarcinoma. Endoscopic ultrasonography (EUS) reveals diffuse hypoechoic pancreatic enlargement, sometimes with hypoechoic inclusions, in patients with AIP. In addition, EUS-elastography and contrast-enhanced harmonic EUS have been developed with promising results. The usefulness of EUS-guided fine-needle aspiration has been increasingly recognized for obtaining adequate tissue samples for the histological diagnosis of AIP. Further improvement of endoscopic procedures and devices will contribute to more accurate diagnosis of AIP and IgG4-SC.

Republished: recent advances in autoimmune pancreatitis: type 1 and type 2

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis characterised clinically by frequent presentation with obstructive jaundice, histologically by a lymphoplasmacytic infiltrate with fibrosis, and therapeutically by a dramatic response to steroids. When so defined, AIP can be sub-classified into two subtypes, 1 and 2. Recent international consensus diagnostic criteria for AIP have been developed for diagnosis of both forms of AIP. Type 1 AIP is the pancreatic manifestation of a multiorgan disease, recently named IgG4-related disease. Little is known about the pathogenesis of either form of AIP. Despite frequent association of type 1 AIP with elevated serum IgG4 levels and infiltration with IgG4-positive plasma cells, it is unlikely that IgG4 plays a pathogenic role in AIP. Type 1 AIP responds to steroids, but there needs to be consensus on treatment regimens for induction and therapeutic end points. Relapses are common, but can be reduced by long-term use of low-dose steroids. Recent reports suggest that immunomodulators (azathioprine, 6-mercaptopurine and mycophenolate mofetil), as well biological agents (the antibody to CD20, rituximab) may have a role in maintaining remission in relapsing type 1 AIP. Future studies should clarify the best management options for treatment of relapses and maintenance of remission. Type 2 AIP is a pancreas-specific disorder not associated with IgG4. It presents in younger individuals equally with obstructive jaundice and pancreatitis. The inflammatory process responds to steroid therapy; relapses are uncommon. The clinical spectrum and long-term outcomes of medically treated type 2 AIP are still being evaluated.

Role of endoscopy in the diagnosis of autoimmune pancreatitis and immunoglobulin G4-related sclerosing cholangitis

Autoimmune pancreatitis (AIP) must be differentiated from pancreatic carcinoma, and immunoglobulin (Ig)G4-related sclerosing cholangitis (SC) from cholangiocarcinoma and primary sclerosing cholangitis (PSC). Pancreatographic findings such as a long narrowing of the main pancreatic duct, lack of upstream dilatation, skipped narrowed lesions, and side branches arising from the narrowed portion suggest AIP rather than pancreatic carcinoma. Cholangiographic findings for PSC, including band-like stricture, beaded or pruned-tree appearance, or diverticulum-like outpouching are rarely observed in IgG4-SC patients, whereas dilatation after a long stricture of the bile duct is common in IgG4-SC. Transpapillary biopsy for bile duct stricture is useful to rule out cholangiocarcinoma and to support the diagnosis of IgG4-SC with IgG4-immunostaining. IgG4-immunostaining of biopsy specimens from the major papilla advances a diagnosis of AIP. Contrast-enhanced endoscopic ultrasonography (EUS) and EUS elastography have the potential to predict the histological nature of the lesions. Intraductal ultrasonographic finding of wall thickening in the non-stenotic bile duct on cholangiography is useful for distinguishing IgG4-SC from cholangiocarcinoma. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is widely used to exclude pancreatic carcinoma. To obtain adequate tissue samples for the histological diagnosis of AIP, EUS-Tru-cut biopsy or EUS-FNA using a 19-gauge needle is recommended, but EUS-FNA with a 22-gauge needle can also provide sufficient histological samples with careful sample processing after collection and rapid motion of the FNA needles within the pancreas. Validation of endoscopic imaging criteria and new techniques or devices to increase the diagnostic yield of endoscopic tissue sampling should be developed.

Amendment of the Japanese Consensus Guidelines for Autoimmune Pancreatitis, 2013 I. Concept and diagnosis of autoimmune pancreatitis

BACKGROUND

In response to the proposal of the international consensus diagnostic criteria (ICDC) for autoimmune pancreatitis (AIP) and the Japanese diagnostic criteria in 2011, the 2009 Japanese consensus guidelines for managing AIP required revision.

METHODS

Three committees [the professional committee for making clinical questions (CQs) and statements by Japanese specialists, the expert panelist committee for rating statements by the modified Delphi method, and the evaluating committee by moderators] were organized. Fifteen specialists for AIP extracted the specific clinical statements from 1,843 articles published between 1963 and 2012 (obtained from Pub Med and a secondary database, and developed the CQs and statements. The expert panel individually rated the clinical statements using a modified Delphi approach, in which a clinical statement receiving a median score greater than seven on a nine-point scale from the panel was regarded as valid.

RESULTS

The professional committee created 13 CQs and statements for the current concept and diagnosis of AIP, 6 for extra-pancreatic lesions, 6 for differential diagnosis, and 11 for treatment.

CONCLUSION

After evaluation by the moderators, amendments to the Japanese consensus guidelines for AIP have been proposed for 2013.

The role of CD19+ CD24high CD38high and CD19+ CD24high CD27+ regulatory B cells in patients with type 1 autoimmune pancreatitis

BACKGROUND

Patients with type 1 autoimmune pancreatitis (AIP) have several immunologic and histologic abnormalities. It is known that depletion of B cells by rituximab is effective for treatment of IgG4-related disease (IgG4-RD) such as type 1 AIP, suggesting that B cells may be a key player in IgG4-RD. However, the role of regulatory B cells (Bregs) in type 1 AIP is unclear, and the objective of this paper is to clarify the role of Bregs in the pathophysiology of type 1 AIP by analyzing circulating Bregs.

METHOD

We recruited 21 patients with type 1 AIP as determined by the International Consensus Diagnostic Criteria for AIP (ICDC). No patients received corticosteroid treatments. For comparison, we recruited 14 patients with chronic pancreatitis (CP), 20 patients with pancreatic cancer, and 25 healthy subjects as controls. We analyzed Bregs as CD19+ CD24high CD38high and CD19+ CD24high CD27+ from peripheral blood by flow cytometry.

RESULTS

In peripheral blood, CD19+ CD24high CD38high Bregs were significantly increased in type 1 AIP patients compared with CP, pancreatic cancer, and healthy controls. Although not significant different, CD19+ CD24high CD27+ Bregs of type 1 AIP were decreased compared to those of other groups. IL-10(+) B cells were not significantly different from type 1 AIP patients and healthy controls. In untreated type 1 AIP patients, the number of CD19+ CD24high CD38high Bregs and IgG4 were not correlated.

CONCLUSIONS

Our data suggested that CD19+ CD24high CD38high Bregs seemed to increase reactively to suppress the disease activity, and are consistent with the hypothesis that CD19+ CD24high CD27+ Bregs might be involved in the development of type 1 AIP, although it still remains unclear whether the decrease of CD19+ CD24high CD27+ cells is cause or effect of AIP.

Diagnosis and classification of autoimmune pancreatitis

Recent studies suggested the existence of two subtypes of autoimmune pancreatitis (AIP): type 1 related with IgG4 as the pancreatic manifestation of IgG4-related disease (IgG4-RD), and type 2 related with a granulocytic epithelial lesion. Apart from type 2 AIP, the characteristic features of type 1 AIP are increased serum IgG4 levels, lymphoplasmacytic sclerosing pancreatitis (abundant infiltration of IgG4+ plasmacytes and lymphocytes, storiform fibrosis, and obliterative phlebitis), extra-pancreatic manifestations of IgG4-RD (e.g. sclerosing cholangitis, sclerosing sialadenitis, retroperitoneal fibrosis), and steroid responsiveness. Although the way how to diagnose IgG4-RD has not been established yet, the Comprehensive Diagnostic Criteria (CDC) for IgG4-RD for general use, and several organ specific criteria for AIP have been proposed; the International Consensus Diagnostic Criteria (ICDC) and the revised clinical diagnostic criteria in 2011 by Japan Pancreas Society (JPS-2011) for type1 AIP. In cases of probable or possible IgG4-RD diagnosed by the CDC, organ specific diagnostic criteria should be concurrently used according to an algorithm of diagnosis for IgG4-RD with reference to the specialist.

Concurrent autoimmune pancreatitis and primary biliary cirrhosis: a rare case report and literature review

Background

Both autoimmune pancreatitis (AIP) and primary biliary cirrhosis (PBC) are related to various diseases. But the concurrence of AIP and PBC is extremely rare, with only 2 cases reported. Here we report the concurrence of AIP and PBC in a Chinese patient for the first time.

Case presentation

A 65-year-old male was admitted to our hospital with jaundice, pruritus, mild abdominal pain and darkening urine. Serum alkaline phosphatase, γ-glutamyltransferase, bilirubin and IgG4 were prominently elevated. The antimitochondrial antibody was positive. Radiological examination revealed diffusive enlargement of the pancreas. Pancreatic biopsy showed lymphoplasmacytic infiltration, fibrosis and abundant IgG4+ plasma cells. The patient was diagnosed with AIP and PBC. Nasobiliary tube was placed to facilitate biliary drainage. A combination therapy of steroid and UDCA was administered and the patient was gradually recovered, during which the patient was complicated with biliary infecion, herpes zoster and pulmonary abscess.

Conclusion

We present this case together with literature evidence to support the concurrence of AIP and PBC, share our experience of using combination therapy with steroid and UDCA, and raise the awareness of infectious complications in immunosuppressed patients.

Mechanisms and assessment of IgG4-related disease: lessons for the rheumatologist

Recognition of IgG4-related disease as an independent chronic inflammatory disorder is a relatively new concept; previously, the condition was thought to represent a subtype of Sjögren's syndrome. IgG4-related disease is characterized by elevated serum levels of IgG4 and inflammation of various organs, with abundant infiltration of IgG4-bearing plasma cells, storiform fibrosis and obliterative phlebitis representing the major histopathological features of the swollen organs. The aetiology and pathogenesis of this disorder remain unclear, but inflammation and subsequent fibrosis occur due to excess production of type 2 T-helper-cell and regulatory T-cell cytokines. The disease can comprise various organ manifestations, such as dacryoadenitis and sialadenitis (also called Mikulicz disease), type 1 autoimmune pancreatitis, kidney dysfunction and lung disease. Early intervention using glucocorticoids can improve IgG4-related organ dysfunction; however, patients often relapse when doses of these agents are tapered. The disease has also been associated with an increased incidence of certain malignancies. Increased awareness of IgG4-related disease might lead to consultation with rheumatologists owing to its clinical, and potentially pathogenetic, similarities with certain rheumatic disorders. With this in mind, we describe the pathogenic mechanisms of IgG4-related disease, and outline considerations for diagnosis and treatment of the condition.

International Consensus Diagnostic Criteria for Autoimmune Pancreatitis and Its Japanese Amendment Have Improved Diagnostic Ability over Existing Criteria

Objectives. The recent International Consensus Diagnostic Criteria (ICDC) for autoimmune pancreatitis (AIP) and its Japanese amendment developed by the Japanese Pancreas Society (JPS 2011) may have overcome the drawbacks of earlier criteria and achieved a higher diagnostic ability for AIP. The aim of the present study is to evaluate this possibility and identify the underlying causes of this change. Methods. We compared the diagnostic abilities of the ICDC and JPS 2011 with those of the Japanese diagnostic criteria 2006 (JPS 2006), Korean diagnostic criteria (Korean), Asian diagnostic criteria (Asian), and HISORt diagnostic criteria in 110 patients with AIP and 31 patients with malignant pancreatic cancer. Results. The ICDC achieved the highest diagnostic ability in terms of accuracy (95.0%), followed by JPS 2011 (92.9%), Korean (92.2%), HISORt (88.7%), Asian (87.2%), and JPS 2006 (85.1%). Nearly all criteria systems exhibited a high specificity of 100%, indicating that the enhanced diagnostic ability of the ICDC and JPS 2011 likely stemmed from increased sensitivity brought about by inclusion of diagnostic items requiring no endoscopic retrograde pancreatography. The diagnostic ability of JPS 2011 was nearly equivalent to that of the ICDC. Conclusions. The ICDC and JPS 2011 have improved diagnostic ability as compared with earlier criteria sets because of an increase in sensitivity.

Capability and limitations of recent diagnostic criteria for autoimmune pancreatitis

Because a diagnostic serological marker is unavailable, autoimmune pancreatitis (AIP) is diagnosed based on unique features. The diagnostic capabilities and potential limitations of four sets of diagnostic criteria for AIP (Japanese diagnostic criteria 2006 and 2011, Asian diagnostic criteria, and international consensus diagnostic criteria (ICDC)) were compared among 85 patients who were diagnosed AIP according to at least one of the four sets. AIP was diagnosed in 87%, 95%, 95%, and 95% of the patients according to the Japanese 2006, Asian, ICDC, and Japanese 2011 criteria, respectively. The ICDC can diagnose types 1 and 2 AIP independently and show high sensitivity for diagnosis of AIP. However, as the ICDC are rather complex, diagnostic criteria for AIP should perhaps be revised and tailored to each country based on the ICDC.

Recent advances in autoimmune pancreatitis: type 1 and type 2

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis characterised clinically by frequent presentation with obstructive jaundice, histologically by a lymphoplasmacytic infiltrate with fibrosis, and therapeutically by a dramatic response to steroids. When so defined, AIP can be sub-classified into two subtypes, 1 and 2. Recent international consensus diagnostic criteria for AIP have been developed for diagnosis of both forms of AIP. Type 1 AIP is the pancreatic manifestation of a multiorgan disease, recently named IgG4-related disease. Little is known about the pathogenesis of either form of AIP. Despite frequent association of type 1 AIP with elevated serum IgG4 levels and infiltration with IgG4-positive plasma cells, it is unlikely that IgG4 plays a pathogenic role in AIP. Type 1 AIP responds to steroids, but there needs to be consensus on treatment regimens for induction and therapeutic end points. Relapses are common, but can be reduced by long-term use of low-dose steroids. Recent reports suggest that immunomodulators (azathioprine, 6-mercaptopurine and mycophenolate mofetil), as well biological agents (the antibody to CD20, rituximab) may have a role in maintaining remission in relapsing type 1 AIP. Future studies should clarify the best management options for treatment of relapses and maintenance of remission. Type 2 AIP is a pancreas-specific disorder not associated with IgG4. It presents in younger individuals equally with obstructive jaundice and pancreatitis. The inflammatory process responds to steroid therapy; relapses are uncommon. The clinical spectrum and long-term outcomes of medically treated type 2 AIP are still being evaluated.

PRSS1_p.Leu81Met mutation results in autoimmune pancreatitis

AIM: To describe protease serine 1 (PRSS1) gene mutations in patients with autoimmune pancreatitis (AIP) and the clinical features of AIP.

METHODS: Fourteen patients with AIP, 56 with other chronic pancreatitis, 254 with pancreatic cancer and 120 normal controls were studied. The mutations and polymorphisms of four genes involved with pancreatitis or pancreatic cancer, PRSS1, SPINK1, CFTR and MEN1, were sequenced. The pathogenic mechanism of AIP was investigated by comparing the wild-type expression system with the p.81Leu→Met mutant expression system.

RESULTS: Two novel mutations (p.81Leu→Met and p.91Ala→Ala) were found in PRSS1 gene from four patients with AIP. PRSS1_p.81Leu→Met mutation led to a trypsin display reduction (76.2%) combined with phenyl agarose (Ca²⁺ induced failure). Moreover, the ratio of trypsin/amylase in patients with AIP was higher than in the patients with pancreatic cancer and other pancreatitis. A large number of lymphocytes and plasma cells were found in the bile ducts accompanied by hyperplasia of myofibroblasts.

CONCLUSION: Autoimmune pancreatitis may be related to PRSS1 gene mutations.

Membranous nephropathy associated with type 1 autoimmune pancreatitis and dominant glomerular IgG4 deposit

We report a case of membranous nephropathy associated with type 1 autoimmune pancreatitis. A 58-year-old man presented with anorexia. Work-up revealed a mass in the pancreatic head, which was subsequently resected. Pathological examination showed diffuse infiltration of immunoglobulin (Ig) G4-positive plasma cells, which was compatible with the diagnosis of type 1 autoimmune pancreatitis. Serum IgG4 was elevated. He developed nephrotic syndrome around the time of the surgery. Kidney biopsy confirmed the diagnosis of membranous nephropathy. Immunofluorescent staining showed predominant glomerular IgG4 deposit among IgG subclasses. Tubulointerstitial nephritis, which is usually a dominant feature of renal involvement in IgG4-related disease, was not observed. The patient was treated with prednisolone and several immunosuppressants. During the course, the degree of proteinuria was associated with the serum IgG4 level. Serum antibody against phospholipase A2 receptor was negative. These findings together with IgG4-dominant glomerular deposit suggest that IgG4 may play a unique role in the pathogenesis of secondary membranous nephropathy caused by IgG4-related diseases.