Standard steroid treatment for autoimmune pancreatitis

Autoimmune pancreatitis

The purpose of this review is to provide a concise view of the existing knowledge of autoimmune pancreatitis (AIP) for practicing clinicians. AIP is a rare disease whose recognition and understanding are evolving. It is a type of chronic pancreatitis that often presents as obstructive jaundice, has a distinctive histology, and is exquisitely sensitive to steroid therapy. This form of chronic pancreatitis has a unique clinical, biochemical, and radiological profile. The term "AIP" encompasses two subtypes: types 1 and 2. Type 1 AIP is the pancreatic manifestation of a systemic fibro-inflammatory disease called immunoglobulin G4-associated systemic diseases. Type 2 AIP has been shown to be associated with inflammatory bowel disease. Existing criteria are geared towards the diagnosis of type 1 AIP. At present, pancreatic histology is a requirement for the definitive diagnosis of type 2 AIP. AIP can mimic most other pancreatic diseases in its presentation, but in clinical practice, it often has to be differentiated from pancreatic cancer. There are established criteria and algorithms not only to diagnose AIP, but also to differentiate it from pancreatic cancer. The utility of these algorithms and the approach to management are discussed here.

Characteristics of autoimmune pancreatitis based on serum IgG4 level

BACKGROUND

Autoimmune pancreatitis is categorized as an IgG4-related autoimmune disease, mostly associated with serological alterations, however characteristics of autoimmune pancreatitis based on serum markers have not been fully evaluated.

METHODS

We evaluated demographics, symptoms, imaging and therapeutic outcome in 27 cases of autoimmune pancreatitis stratified by serum IgG4 level.

RESULTS

Twenty patients (74%) had elevated serum IgG4 and 7 (26%) had normal IgG4 levels. Compared to patients with normal serum IgG4 levels, patients with elevated IgG4 had higher incidence of jaundice at onset (14.3% vs. 80%, respectively; P=0.002), more frequent diffuse pancreatic enlargement at imaging (14.3% vs. 60%, respectively; P=0.04), significantly higher 18F-2-fluoro-2-deoxy-d-glucose uptake of pancreatic lesions (SUV max: 4.0 vs. 5.7, respectively; P=0.02), more frequent extrapancreatic lesions (42.9% vs. 85%, respectively; P=0.03). Response to steroids was recognized regardless of serum IgG4 level, however maintenance therapy was required more frequently amongst patients with elevated compared to normal IgG4 (85.7% vs. 33.3%, respectively; P=0.04).

CONCLUSIONS

Clinical features of autoimmune pancreatitis are different based on level of serum IgG4. Further studies are needed to clarify if normal serum IgG4 cases are a precursor of active type 1 or type 2 autoimmune pancreatitis.

Management strategies for autoimmune pancreatitis

INTRODUCTION

Autoimmune pancreatitis (AIP) is a newly developed concept for a peculiar type of pancreatitis, and at present is recognized as a pancreatic lesion reflecting IgG4-related systemic disease. It is of utmost importance to differentiate AIP from pancreatic cancer to avoid unnecessary surgery.

AREAS COVERED

The current management strategies for AIP, including its clinical features, diagnostic criteria, clinical subtypes, steroid therapy and prognosis are discussed, based on our 66 AIP cases and papers searched in PubMed from 1992 to March 2011, using the term 'autoimmune pancreatitis'. A new clinicopathological entity, an 'IgG4-related sclerosing disease' is also mentioned.

EXPERT OPINION

AIP should be considered in the differential diagnosis in elderly male patients presented with obstructive jaundice and pancreatic mass. Steroids are a standard therapy for AIP, but their regimen including maintenance therapy should be evaluated in prospective trials.

Characteristics of pancreatic diabetes in patients with autoimmune pancreatitis

OBJECTIVE

Although patients with autoimmune pancreatitis (AIP) tend to have concurrent diverse disorders, very few studies have focused on diabetes mellitus (DM) coexisting with AIP.

METHODS

In total 102 AIP patients with DM were divided into three groups. Those with DM before the onset of AIP were labeled group A (n=35), those who developed DM and AIP simultaneously were labeled group B (n=58) and those who developed DM after steroid therapy for AIP were labeled group C (n=9). The characteristics of DM among the three groups were evaluated.

RESULTS

No significant differences were noted in the age of DM onset among the three groups. However, the mean duration of DM was significantly longer in group A (8.7 years) than in groups B and C. AIP developed 6.8 years after DM onset in group A, whereas it developed 1.8 years after steroid therapy in group C. Group A had the highest rate (25.7%) of family members with a history of AIP. Levels of serum albumin, total cholesterol and triglyceride were significantly lower in group A. No correlations were found between glycated hemoglobin and benzoyl-tyrosyl para-aminobenzoic acid. Hypoglycemia was observed in 20% of patients under insulin therapy. Most of them were habitual drinkers and received no pancreatic enzymes. Group A showed a high prevalence of retinopathy, nephropathy and macrovascular disorders than group B.

CONCLUSION

Aspects of AIP-associated pancreatic diabetes were clarified. AIP-associated DM must be controlled by a full assessment of the pancreatic endocrine and exocrine function.

Factors predictive of relapse and spontaneous remission of autoimmune pancreatitis patients treated/not treated with corticosteroids

BACKGROUND

Relapse and spontaneous remission (SR) are characteristic features of autoimmune pancreatitis (AIP).

AIM AND METHODS

We conducted a study to determine if the predictive factors might be potentially related to the relapse in 70 consecutive AIP patients. Regarding SR, we studied the data of patients without corticosteroid treatment (CST).

RESULTS

CST was administered to 60% (42/70) of the patients; however, relapse was noted in 45.2% (19/42) of these patients. In 95% (18/19) of the AIP patients developing relapse, the relapse occurred within 3 years. The relapse rate was 80% (12/15) in the AIP patients administered CST for less than 12 months and 25.9% (7/27) in those administered CST for over 12 months (p < 0.01). The results of univariate analysis revealed significant association of relapse with the presence of jaundice, IgG4 seropositivity, presence of diffuse pancreas swelling, duodenal papillitis (DP), history of initial CST, and history of supportive treatment (p < 0.05), whereas multivariate analysis revealed that IgG4 seropositivity (OR 10.506, p = 0.0422) and the presence of jaundice (OR 6.945, p = 0.0174) are significant independent factors predictive of relapse in AIP patients. SR was recognized in 65.0% (13/20) of AIP patients without CST. The results of univariate analysis revealed that SR was associated with IgG4 seropositivity (p < 0.05), and multivariate analysis identified IgG4 seropositivity (OR 0.032, p = 0.0092) as a significant independent factor predictive of SR in these cases.

CONCLUSION

AIP patients with IgG4 seropositivity and jaundice are at a higher risk of relapse and they could therefore be candidates for over 3 years of maintenance CST. AIP patients with IgG4 seronegativity have a high likelihood of SR.

Comparison of steroid pulse therapy and conventional oral steroid therapy as initial treatment for autoimmune pancreatitis

BACKGROUND

The efficacy of oral steroid therapy for autoimmune pancreatitis (AIP) is well known, and oral prednisolone treatment is most usually commenced at 30-40 mg/day, but there have been few reports about comparative studies of oral steroid therapy and steroid pulse therapy as the initial treatment for AIP. We studied the clinical course and image findings to estimate the utility of steroid pulse therapy for AIP, comparing it with oral steroid therapy.

METHODS

Laboratory and image findings were assessed retrospectively in 11 patients who received steroid pulse therapy, and the findings were compared to those in 10 patients who received conventional oral steroid therapy.

RESULTS

Change in pancreatic size showed no significant difference between the therapies after 2 weeks of treatment. Significant improvement of lower bile duct strictures after 2 weeks of treatment and that of immunoglobulin values within 6 months were shown with both therapies. However, steroid pulse therapy showed significant improvement of γ-guanosine triphosphate (GTP) in 2 weeks and of alanine aminotransferase (ALT) in 2 and 8 weeks, compared with oral steroid therapy. Moreover, there was one patient in whom the lower bile duct stricture was not improved by oral steroid therapy, but it did show improvement with steroid pulse therapy.

CONCLUSIONS

Initial steroid pulse therapy is a beneficial alternative to oral steroid therapy for the improvement of bile duct lesions. In future, the accumulation of a larger number of patients receiving steroid pulse therapy is needed, and prospective studies will be required.

Treatment approaches to IgG4-related systemic disease

PURPOSE OF REVIEW

IgG4-related systemic disease (IgG4-RSD) is a systemic fibroinflammatory condition that can affect any organ system. Prompt recognition and management of this disease process are necessary to prevent sclerosis and permanent organ damage. Here, we review the advances in treatment approaches to IgG4-RSD.

RECENT FINDINGS

Most information regarding treatment is derived from retrospective case series of patients with autoimmune pancreatitis (AIP), and follow-up periods have generally been short. A variety of IgG4-RSD presentations respond rapidly to glucocorticoid treatment. Glucocorticoids have become a standard therapy for AIP, but the indications requiring treatment as well as the appropriate starting dose and duration of therapy remain controversial. The importance of maintenance of glucocorticoids following remission induction is debatable. As our knowledge grows regarding other organ manifestations of IgG4-RSD with longer follow-ups, the necessity of steroid-sparing agents to manage frequent relapses becomes clear.

SUMMARY

The natural history and long-term prognosis of IgG4-RSD are not well understood. Large prospective studies and randomized controlled trials of patients with wide spectrum manifestations of IgG4-RSD are required to support better approaches to treatment.

Serologic issues in IgG4-related systemic disease and autoimmune pancreatitis

PURPOSE OF REVIEW

IgG4-related systemic disease (ISD) is a recently recognized syndrome affecting multiple organs. Autoimmune pancreatitis (AIP) is the pancreatic manifestation of ISD and mimics pancreatic cancer. Current data show frequent association with serum IgG4 elevation and other serologic abnormalities. Here we explore the diagnostic and possible prognostic utility and pathogenetic implications of serologic abnormalities in ISD.

RECENT FINDINGS

Serum IgG4 elevations (>140 mg/dl) are seen in 70-80% of AIP patients and also in 5% of normal population and 10% of pancreatic cancer making it an unsuitable single marker for diagnosis. However, when combined with other features of AIP, it can be of great diagnostic value though its utility in monitoring of therapy or as a marker or predictor of relapse is limited. Several other antibodies have been identified in AIP against pancreas-specific antigens like trypsinogens I and II, pancreatic secretory trypsin inhibitor (PSTI) and plasminogen binding protein (PBP) and other nonpancreas-specific antigens. Anti-PBP antibodies appear to have potential diagnostic utility but require further validation.

SUMMARY

No single serologic marker is diagnostic of ISD. Serum IgG4 elevation has convincing diagnostic utility when combined with other disease features although its value in disease monitoring may be limited.

Autoimmune pancreatitis and IgG4-related sclerosing cholangitis

PURPOSE OF REVIEW

Autoimmune pancreatitis (AIP) is a peculiar type of pancreatitis with a presumed autoimmune etiology. AIP is frequently associated with stenosis of the bile duct in the form of IgG4-related sclerosing cholangitis. This article reviews recent advances in clinicopathological findings for AIP and IgG4-related sclerosing cholangitis.

RECENT FINDINGS

AIP is currently diagnosed based on characteristic radiological findings (irregular narrowing of the main pancreatic duct and enlargement of the pancreas) in combination with serological findings (elevated serum IgG4 and presence of autoantibodies) and histopathological findings (dense infiltration of IgG4-positive plasma cells and lymphocytes with fibrosis and obliterative phlebitis in the pancreas). Other clinical characteristics include preponderance toward elderly men, common initial symptoms of obstructive jaundice, and favorable response to steroid therapy. Differentiation of AIP from pancreatic cancer is crucial. As AIP is frequently associated with various sclerosing extrapancreatic lesions showing the same peculiar histological findings seen in the pancreas, AIP is currently considered to represent a pancreatic manifestation of IgG4-related sclerosing disease. Considering the age of onset, associated diseases, cholangiography, serum IgG4 levels, and steroid responsiveness, IgG4-related sclerosing cholangitis differs from primary sclerosing cholangitis.

SUMMARY

AIP and associated extrapancreatic lesions are considered to represent clinical manifestations of IgG4-related sclerosing disease.

Clinical characteristics of 327 Asian patients with autoimmune pancreatitis based on Asian diagnostic criteria

OBJECTIVES

To clarify the clinical and pathophysiological characteristics of autoimmune pancreatitis (AIP) in Asia.

METHODS

A retrospective, actual situation survey of AIP diagnosed by Asian criteria was conducted in 10 centers of Japan, Korea, Taiwan, China, and India.

RESULTS

A total of 327 AIP cases (258 male and 69 female subjects; average age, 60.0 years) were enrolled. Obstructive jaundice was the most frequent initial symptom (46%-74%), followed by weight loss (4%-51%) and abdominal pain (19%-44%). Diffuse swelling of the pancreas was frequent in Japan (64%) and Korea (81%), but segmental swelling of the pancreas was more frequent in Taiwan (70%) and China (72%) (P < 0.01). Serum immunoglobulin G4 levels were elevated in 58%-100% of cases in Japan, Korea, and Taiwan. Pathologically, almost all AIPs in Asia were lymphoplasmacytic sclerosing pancreatitis. Sclerosing cholangitis was the most frequent extrapancreatic lesion (60%-81%). Steroid therapy was a major and effective therapeutic strategy in Japan, Korea, and Taiwan. However, the rate of resection or bypass operation was higher in Taiwan (40%) and China (72%) (P < 0.01).

CONCLUSIONS

Features of AIP are fundamentally similar in Japan, Korea, Taiwan, and China. Knowledge of emerging AIP should be more widespread in Asia to avoid unnecessary operation.

Review article: autoimmune pancreatitis - management of an emerging disease

BACKGROUND

Autoimmune pancreatitis is a steroid-responsive inflammatory pancreatic disease considered to be part of an immunoglobulin G4 (IgG4)-associated systemic disease.

AIM

To review the management of autoimmune pancreatitis.

METHODS

We conducted a PubMed search using the following key words: autoimmune pancreatitis, IgG4-associated systemic disease, IgG4-associated cholangitis, diagnosis, natural history, treatment.

RESULTS

Although there are reports of spontaneous resolution of autoimmune pancreatitis, steroids have been shown to be effective in inducing remission, reducing the frequency of relapse and that of long-term unfavourable events compared to historical controls. There are no randomised data on autoimmune pancreatitis treatment. Oral steroids are used for induction of remission. Reported response results are excellent with variable proportions of patients achieving remission in different studies. After a period of 2-4 weeks, steroids are tapered and usually withdrawn within several months, although long-term maintenance therapy for all autoimmune pancreatitis patients has also been proposed. Disease relapse occurs in more than 40% of patients and can be effectively treated with additional immunosuppression, including azathioprine.

CONCLUSIONS

Steroids are effective in inducing remission and in treating relapse in patients with autoimmune pancreatitis. Randomised trials on autoimmune pancreatitis therapy are lacking. To date, questions concerning the timing, choice and duration of long-term immunosuppression remain unanswered.

Histopathologic and clinical subtypes of autoimmune pancreatitis: the honolulu consensus document

Autoimmune pancreatitis (AIP) has been extensively reported from Japan, Europe and the USA. While the descriptions of AIP from Japan have predominantly been based on the presence of a distinct clinical phenotype, reports from Europe and the USA describe at least 2 histopathologic patterns in patients diagnosed with AIP, namely lymphoplasmacytic sclerosing pancreatitis (LPSP) and idiopathic duct-centric pancreatitis (IDCP) or granulocytic epithelial lesion- positive pancreatitis. While the 2 entities share common histopathologic features (periductal lymphoplasmacytic infiltration and peculiar periductal fibrosis), expert pathologists can accurately distinguish them on the basis of other unique histopathologic features. Clinically, the 2 entities have a similar presentation (obstructive jaundice/pancreatic mass and a dramatic response to steroids), but they differ significantly in their demography, serology, involvement of other organs and disease relapse rate. While LPSP is associated with elevation of titers of nonspecific autoantibodies and serum IgG4 levels, IDCP does not have definitive serologic autoimmune markers. All experts agreed that the clinical phenotypes associated with LPSP and IDCP should be nosologically distinguished; however, their terminology was controversial. While most experts agreed that the entities should be referred to as type 1 and type 2 AIP, respectively, others had concerns regarding use of the term 'autoimmune' to describe IDCP. and IAP.

Serial changes of elevated serum IgG4 levels in IgG4-related systemic disease

OBJECTIVE

Autoimmune pancreatitis (AIP) and Mikulicz's disease have recently been recognized as pancreatic or salivary gland lesions of IgG4-related systemic disease. These are frequently associated with elevated serum IgG4 levels. This study aimed to clarify clinical implications of serial changes of elevated serum IgG4 levels in IgG4-related systemic diseases.

METHODS

Serial changes of elevated serum IgG4 levels were examined in patients with IgG4-related systemic diseases. Patients Serial changes of elevated serum IgG4 levels were examined in 44 patients: AIP (n=24), Mikulicz's disease (n=8), pancreatic cancer (n=5), bile duct cancer (n=1), sclerosing cholangitis (n=1), hypereosinophilic syndrome (n=1), chronic thyroiditis (n=1), hypophysitis (n=1), idiopathic pancreatitis (n=1), and Behcet's disease (n=1).

RESULTS

The serum IgG4 levels decreased in all patients with AIP and Mikulicz's disease after steroid therapy. The serum IgG4 levels were normalized in 46% of AIP patients and 38% of Mikulicz's disease patients. The serum IgG4 levels were not normalized at remission in 3 of 4 relapsed AIP patients, and re-elevation of serum IgG4 levels was detected in all relapsed patients. Elevated serum IgG4 levels decreased in 3 patients with pancreatic cancer after resection or chemotherapy, and decreased in patients with hypereosinophilic syndrome, sclerosing cholangitis, and hypophysitis after steroid therapy.

CONCLUSION

Measurement of serial serum IgG4 levels is useful to determine the disease activity of IgG4-related systemic diseases.

Outcome of patients with type 1 or 2 autoimmune pancreatitis

OBJECTIVES

Autoimmune pancreatitis (AIP) is better described than before, but there is still no international consensus for definition, diagnosis, and treatment. Our aims were to analyze the short- and long-term outcome of patients with focus on pancreatic endocrine and exocrine functions, to search for predictive factors of relapse and pancreatic insufficiency, and to compare patients with type 1 and type 2 AIP.

METHODS

All consecutive patients followed up for AIP in our center between 1999 and 2008 were included. Two groups were defined: (a) patients with type 1 AIP meeting HISORt (Histology, Imaging, Serology, Other organ involvement, and Response to steroids) criteria; (b) patients with definitive/probable type 2 AIP including those with histologically confirmed idiopathic duct-centric pancreatitis ("definitive") or suggestive imaging, normal serum IgG4, and response to steroids ("probable"). AIP-related events and pancreatic exocrine/endocrine insufficiency were looked for during follow-up. Predictive factors of relapse and pancreatic insufficiency were analyzed.

RESULTS

A total of 44 patients (22 males), median age 37.5 (19-73) years, were included: 28 patients (64%) with type 1 AIP and 16 patients (36%) with type 2 AIP. First-line treatment consisted of steroids or pancreatic resection in 59 and 27% of the patients, respectively. Median follow-up was 41 (5-130) months. Steroids were effective in all treated patients. Relapse was observed in 12 patients (27%), after a median delay of 6 months (1-70). Four patients received azathioprine because of steroid resistance/dependence. High serum IgG4 level, pain at time of diagnosis, and other organ involvement were associated with relapse (P<0.05). At the end point, pancreatic atrophy was observed in 35% of patients. Exocrine and endocrine insufficiencies were present in 34 and 39% of the patients, respectively. At univariate analysis, no factor was associated with exocrine insufficiency, although female gender (P=0.04), increasing age (P=0.006), and type 1 AIP (P=0.001) were associated with the occurrence of diabetes. Steroid/azathioprine treatment did not prevent pancreatic insufficiency. Type 2 AIP was more frequently associated with inflammatory bowel disease than type 1 AIP (31 and 3%, respectively), but relapse rates were similar in both groups.

CONCLUSIONS

Relapse occurs in 27% of AIP patients and is more frequent in patients with high serum IgG4 levels at the time of diagnosis. Pancreatic atrophy and functional insufficiency occur in more than one-third of the patients within 3 years of diagnosis. The outcome of patients with type 2 AIP, a condition often associated with inflammatory bowel disease, is not different from that of patients with type 1 AIP, except for diabetes.

IgG4-related systemic disease in a Native American man

IgG4-related systemic disease is a recently described entity that can elude even the most astute diagnostician. Patients with the disease, characterized by the infiltration of polyclonal IgG4-positive plasmacytes, can present with single or multi-organ involvement. Manifestations include dacryoadenitis, sialadenitis, thyroiditis, pneumonitis, retroperitoneal fibrosis, pancreatitis, sclerosing cholangitis, tubulointerstitial nephritis, prostatitis, and hypophysitis. We describe a biopsy-confirmed case with extensive multi-organ involvement, including hypophysitis, dacryoadenitis, retroperitoneal fibrosis and tubulointerstitial nephritis. By reporting this case, we hope to bring IgG4-related systemic disease to the attention of the broader medical community as it is an elusive disease that commonly responds to systemic corticosteroids.

Autoimmune pancreatitis complicated by carcinoma of the pancreatobiliary system: a case report and review of the literature

We present the case of a 67-year-old woman who developed a metastatic adenocarcinoma of the pancreatobiliary system shortly after the histologically confirmed diagnosis of autoimmune pancreatitis (AIP). This case highlights the need for increased alertness not only in differentiating AIP from pancreatic cancer at the time of diagnosis, but also to exclude concomitant malignancies of the pancreatobiliary system in the management of histologically confirmed AIP.

Serum IgG4-negative autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis (AIP) is considered to be a pancreatic lesion of IgG4-related systemic disease, but about 20% of AIP patients do not have elevated serum IgG4 levels. This study aimed to clarify the pathophysiology of AIP patients without elevated serum IgG4 levels.

METHODS

Fifty-eight AIP patients were divided into 2 groups: those with elevated serum IgG4 levels (>135 mg/dl; SIgG4-positive AIP) and those without (SIgG4-negative AIP). The 2 groups' clinical, serological, radiological, and histological findings, as well as salivary and lacrimal gland function, were compared.

RESULTS

Serum IgG4 levels were elevated in 45 AIP patients and normal in 13 patients. In SIgG4-negative AIP patients, the female ratio tended to be high; obstructive jaundice was less likely; abdominal pain and acute pancreatitis were more likely; segmental swelling of the pancreatic body and/or tail was more common; sclerosing extrapancreatic lesions, salivary and lacrimal gland dysfunction, and abundant infiltration of IgG4-positive plasma cells in the gastric mucosa were less likely; and conservative follow-up was sometimes implemented. Histological examination of the pancreas of SIgG4-negative AIP showed lymphoplasmacytic sclerosing pancreatitis (LPSP) rather confined to the pancreas (n = 4), inadequate material (n = 2), and pancreatic fibrosis showing infiltration of lymphocytes without infiltration of IgG4-positive cells or neutrophils (n = 2).

CONCLUSIONS

Clinicopathological features of SIgG4-negative AIP differed from those of SIgG4-positive AIP. Some SIgG4-negative AIP cases are LPSP rather confined to the pancreas. SIgG4-negative AIP may include idiopathic duct-centric pancreatitis (IDCP) or sclerosing pancreatitis other than LPSP or IDCP, but further studies are needed to clarify this issue.

A mouse model of autoimmune pancreatitis with salivary gland involvement triggered by innate immunity via persistent exposure to avirulent bacteria

The pathogenesis of autoimmune pancreatitis (AIP) remains unknown. Here, we investigated the possible involvement of chronic, persistent exposure to avirulent bacteria in the pathogenesis of AIP. C57BL/6 mice were inoculated with heat-killed Escherichia coli weekly for 8 weeks. At 1 week and up to 12 months after the final inoculation, the mice were killed to obtain samples. At 1 week after the final E. coli inoculation, marked cellular infiltration with fibrosis was observed in the exocrine pancreas. Cellular infiltration in the exocrine pancreas was still observed up to 12 months after the completion of E. coli inoculation. At 10 months after the final inoculation, duct-centric fibrosis became obvious. Inflammation around the ducts in the salivary glands was also observed. Furthermore, sera from heat-killed E. coli-inoculated mice possessed anti-carbonic anhydrase, anti-lactoferrin, and antinuclear antibodies. Exposure to E. coli-triggered AIP-like pancreatitis in C57BL/6 mice. We propose a hypothetical mechanism for AIP pathogenesis. During the initiation phase, silently infiltrating pathogen-associated molecular patterns (PAMP) and/or antigen(s) such as avirulent bacteria might trigger and upregulate the innate immune system. Subsequently, the persistence of such PAMP attacks or stimulation by molecular mimicry upregulates the host immune response to the target antigen. These slowly progressive steps may lead to the establishment of AIP and associated extrapancreatic lesions. Our model might be useful for clarifying the pathogenesis of AIP.

The therapeutic strategy for autoimmune pancreatitis is subject to the endoscopic features of the duodenal papilla

Autoimmune pancreatitis (AIP) often presents with a swollen duodenal papilla, however, the clinical significance of the duodenal papilla in AIP has not been fully elucidated. Data have shown swollen duodenal papillae shaped like a pear and/or with a submucosal tumor having IgG4-bearing plasma cells. Immunohistopathology has potentially verified duodenal papillitis associated with AIP. FOXP3-positive lymphocytes are also recognized in AIP. AIP has shown spontaneous remission and relapse irrelevance to corticosteroid therapy. The results of a multivariate analysis revealed the absence of a swollen duodenal papilla as the only significant independent factor predictive of spontaneous remission in AIP cases. In addition, the results of another multivariate analysis revealed the presence of a swollen duodenal papilla and the presence of extrapancreatic lesions as the significant independent factors predictive of relapse in these cases. Results suggest that the lack of a swollen duodenal papilla is a predictive factor for spontaneous remission, and thus negates the need to administer corticosteroids in those AIP patients. In contrast, a swollen duodenal papilla and the presence of extrapancreatic lesions are risk factors for relapse, and those AIP patients are candidates for maintenance corticosteroid therapy to reduce relapse. Therefore, the therapeutic strategy such as the indication for corticosteroid administration is subject to the endoscopic features of the duodenal papilla.

Diagnosis and treatment of autoimmune pancreatitis

PURPOSE OF REVIEW

To summarize the existing knowledge of autoimmune pancreatitis (AIP) and to review the progress made in the diagnosis and treatment of AIP in the past year.

RECENT FINDINGS

The term 'AIP' appears to encompass at least two distinct subtypes, type 1 and type 2. Type 1 AIP is the pancreatic manifestation of a systemic fibroinflammatory disease called immunoglobulin G4-associated systemic disease. Type 2 AIP affects younger patients, does not have a gender predilection and is associated with normal serum immunoglobulin G4 levels. Existing criteria are geared toward diagnosis of type 1; type 2 AIP can be definitively diagnosed only on pancreatic histology. Both subtypes respond to corticosteroid therapy. However, there are no standardized protocols for initial treatment or management and prevention of relapses in AIP. A novel antibody for AIP has recently been identified and its performance needs validation from other centers. Newly published strategies for differentiating AIP from pancreatic cancer are available.

SUMMARY

AIP is a rare disease whose recognition and understanding are evolving. Much needs to be elucidated with regard to its cause, pathogenesis, treatment of relapse and long-term outcomes. A multidisciplinary team, familiar with the disease, is critical in making the correct diagnosis.

Autoimmune pancreatitis and IgG4-related sclerosing disease

Autoimmune pancreatitis (AIP) is a unique form of pancreatitis in which the pathogenesis is suspected to involve autoimmune mechanisms. AIP sometimes mimics pancreatic cancer in its presentation, but as AIP responds dramatically to steroid therapy, accurate diagnosis is necessary. AIP is currently diagnosed on the basis of a combination of characteristic clinical, serological, morphological and histopathological features. However, its diagnosis remains a clinical challenge and there are no internationally agreed diagnostic criteria. Another type of AIP called 'idiopathic duct-centric chronic pancreatitis' or 'AIP with granulocytic epithelial lesion' has been reported in Western countries. IgG4-related sclerosing disease is a systemic disease in which IgG4-positive plasma cells and T lymphocytes extensively infiltrate various organs. Organs with tissue fibrosis and obliterative phlebitis, such as the pancreas, salivary gland and retroperitoneum, show clinical manifestations; AIP seems to represent one manifestation of IgG4-related sclerosing disease. As a mass is formed in most cases of IgG4-related sclerosing disease, a malignant tumor is frequently suspected on initial presentation. Clinicians should consider IgG4-related sclerosing disease in the differential diagnosis to avoid unnecessary surgery.

Remission and relapse of autoimmune pancreatitis: focusing on corticosteroid treatment

Autoimmune pancreatitis (AIP) is a type of chronic pancreatitis characterized by swelling of the pancreas, narrowing of the main pancreatic duct, elevation of serum immunoglobulin G or G4 level or presence of several autoantibodies, or lymphoplasmacytic infiltration and fibrosis in the pancreas. However, the pathogenesis of AIP remains unclear, and the natural history and long-term prognosis of AIP are little known. Oral corticosteroid therapy for AIP is recommended. The absolute indications for steroid therapy for AIP are bile duct stenosis and accompanying systemic disease such as retroperitoneal fibrosis and diabetes mellitus. The dosage for remission induction is 30 to 40 mg/d for 1 to 2 months. The remission maintenance is needed to prevent relapse, and 5 to 10 mg/d for at least 6 months is recommended in patients who do not have complete remission. When relapse occurs, the dose used at remission induction can be readministered. Herein, we discuss remission and relapse of AIP, focusing on corticosteroid treatment to help clinicians care for patients with AIP and to help make an ideal treatment protocol of AIP through a review of published data. We tried to define remission and relapse of AIP to help investigate the natural course of AIP.

Differences in clinical profile and relapse rate of type 1 versus type 2 autoimmune pancreatitis

BACKGROUND & AIMS

Autoimmune pancreatitis (AIP) has been divided into subtypes 1 (lymphoplasmacytic sclerosing pancreatitis) and 2 (idiopathic duct centric pancreatitis). We compared clinical profiles and long-term outcomes of types 1 and 2 AIP.

METHODS

We compared clinical presentation, relapse, and vital status of 78 patients with type 1 AIP who met the original HISORt criteria and 19 patients with histologically confirmed type 2 AIP.

RESULTS

At presentation, patients with type 1 AIP were older than those with type 2 AIP (62 +/- 14 vs 48 +/- 19 years; P < .0001) and had a greater prevalence of increased serum levels of immunoglobulin G4 (47/59 [80%] vs 1/6 [17%]; P = .004). Patients with type 1 were more likely than those with type 2 to have proximal biliary, retroperitoneal, renal, or salivary disease (60% vs 0; P < .0001). Inflammatory bowel disease was associated with types 1 and 2 (6% vs 16%; P = .37). During median clinical follow-up periods of 42 and 29 months, respectively, 47% of patients with type 1 and none of those with type 2 experienced a relapse. In type 1 AIP, proximal biliary involvement (hazard ratio [HR], 2.12; P = .038) and diffuse pancreatic swelling (HR, 2.00; P = .049) were predictive of relapse, whereas pancreaticoduodenectomy reduced the relapse rate (vs the corticosteroid-treated group; HR, 0.15; P = .0001). After median follow-up periods of 58 and 89 months (types 1 and 2, respectively), the 5-year survival rates for both groups were similar to those of the age- and sex-matched US population.

CONCLUSIONS

Types 1 and 2 AIP have distinct clinical profiles. Patients with type 1 AIP have a high relapse rate, but patients with type 2 AIP do not experience relapse. AIP does not affect long-term survival.

Histopathologic and clinical subtypes of autoimmune pancreatitis: the Honolulu consensus document

Autoimmune pancreatitis (AIP) has been extensively reported from Japan, Europe, and the United States. Whereas the descriptions of AIP from Japan have predominantly been based on the presence of a distinct clinical phenotype, reports from Europe and the United States describe at least 2 histopathologic patterns in patients' condition currently diagnosed as AIP, viz, lymphoplasmacytic sclerosing pancreatitis (LPSP) and idiopathic duct centric pancreatitis (IDCP) or granulocyte epithelial lesion (GEL)-positive pancreatitis. Although the 2 entities share common histopathologic features (periductal lymphoplasmacytic infiltration and peculiar periductal fibrosis), expert pathologists can accurately distinguish them based on other unique histopathologic features. Clinically, the 2 entities have similar clinical presentation (obstructive jaundice/pancreatic mass and a dramatic response to steroids) but differ significantly in their demography, serological characteristics, other organ involvement, and disease relapse. While LPSP is associated with elevation in titers of nonspecific autoantibodies and serum IgG4 levels, IDCP does not have definitive serological autoimmune markers. All experts agreed that the clinical phenotypes associated with LPSP and IDCP should be nosologically distinguished; however, their terminology was debated. Whereas most experts agreed that the entities should be referred to as type 1 and type 2 AIP, respectively, others had concerns regarding use of the term "autoimmune" to describe IDCP.

Japanese consensus guidelines for management of autoimmune pancreatitis: III. Treatment and prognosis of AIP

Steroid therapy appeared to be a standard treatment for autoimmune pancreatitis (AIP), although some AIP patients improve spontaneously. The indications for steroid therapy in AIP patients are symptoms such as obstructive jaundice, abdominal pain, and back pain, and the presence of symptomatic extrapancreatic lesions. Before steroid therapy, jaundice should be managed by biliary drainage in patients with obstructive jaundice, and blood glucose levels should be controlled in patients with diabetes mellitus. For the initial oral prednisolone dose for induction of remission, 0.6 mg/kg/day is recommended. The initial dose is administered for 2-4 weeks, and the dose is tapered by 5 mg every 1-2 weeks, based on changes in the clinical manifestations, biochemical blood tests (such as liver enzymes and IgG or IgG4 levels), and repeated imaging findings (US, CT, MRCP, ERCP, etc.). The dose is tapered to a maintenance dose (2.5-5 mg/day) over a period of 2-3 months. Steroid therapy should be stopped based on the disease activity in each case. Stopping of maintenance therapy should be planned within at least 3 years in cases with radiological and serological improvement. Re-administration or dose-up of steroid is effective for treating AIP relapses. The prognosis of AIP appears to be good over the short-term with steroid therapy. It is unclear whether the long-term outcome is good because there are many unknown factors, such as relapse, pancreatic exocrine or endocrine dysfunction, and associated malignancy.

Autoimmune pancreatitis without a response to steroid therapy: a case which met criteria after withdrawal of steroid

Autoimmune pancreatitis (AIP) sometimes forms a pancreatic mass lesion, which is often difficult to distinguish from pancreatobiliary malignancy, however it generally responds to steroid therapy. A 70-year-old man was referred to our institute with the suspected diagnosis of pancreatic cancer due to a mass lesion detected at the pancreatic head. Various images demonstrated an ill-defined mass at the enlarged pancreatic head with focal narrowing of the main pancreatic duct. Serum antinuclear antibody (ANA) was negative (x40 dilution) on the onset. Forceps biopsy from the narrowed pancreaticobiliary duct and fine-needle aspiration biopsy under endoscopic ultrasonography (EUS-FNAB) ruled out pancreatobiliary malignancy. Steroid therapy was started at 40 mg per day but was not effective according to subsequent image analyses. Repeated EUS-FNA from the pancreatic mass was performed but was again negative for carcinoma. Seven months later, under steroid-off condition, still no response was recognized in the clinical image but the titer of serum ANA was increased to be positive (x80), satisfying the criteria of AIP in Japan (2006). Although very rare, this is a case meeting Japanese criteria of AIP after withdrawal of steroid without response to steroid in the clinical images, suggesting the necessity of careful follow-up.