Recent advances in autoimmune pancreatitis: concept, diagnosis, and pathogenesis

IgG4-related sclerosing disease, an emerging entity: a review of a multi-system disease

Immunoglobulin G4-related systemic disease (IgG4-RSD) is a recently defined emerging entity characterized by a diffuse or mass forming inflammatory reaction rich in IgG4-positive plasma cells associated with fibrosclerosis and obliterative phlebitis. IgG4-RSD usually affects middle aged and elderly patients, with a male predominance. It is associated with an elevated serum titer of IgG4, which acts as a marker for this recently characterized entity. The prototype is IgG4-related sclerosing pancreatitis or autoimmune pancreatitis (AIP). Other common sites of involvement are the hepatobiliary tract, salivary gland, orbit, and lymph node, however practically any organ can be involved, including upper aerodigestive tract, lung, aorta, mediastinum, retroperitoneum, soft tissue, skin, central nervous system, breast, kidney, and prostate. Fever or constitutional symptoms usually do not comprise part of the clinical picture. Laboratory findings detected include raised serum globulin, IgG and IgG4. An association with autoantibody detection (such as antinuclear antibodies and rheumatoid factor) is seen in some cases. Steroid therapy comprises the mainstay of treatment. Disease progression with involvement of multiple organ-sites may be encountered in a subset of cases and may follow a relapsing-remitting course. The principal histopathologic findings in several extranodal sites include lymphoplasmacytic infiltration, lymphoid follicle formation, sclerosis and obliterative phlebitis, along with atrophy and destruction of tissues. Immunohistochemical staining shows increased IgG4+ cells in the involved tissues (>50 per high-power field, with IgG4/IgG ratio >40%). IgG4-RSD may potentially be rarely associated with the development of lymphoma and carcinoma. However, the nature and pathogenesis of IgG4-RSD are yet to be fully elucidated and provide immense scope for further studies.

Type 1 autoimmune pancreatitis

Before the concept of autoimmune pancreatitis (AIP) was established, this form of pancreatitis had been recognized as lymphoplasmacytic sclerosing pancreatitis or non-alcoholic duct destructive chronic pancreatitis based on unique histological features. With the discovery in 2001 that serum IgG4 concentrations are specifically elevated in AIP patients, this emerging entity has been more widely accepted. Classical cases of AIP are now called type 1 as another distinct subtype (type 2 AIP) has been identified. Type 1 AIP, which accounts for 2% of chronic pancreatitis cases, predominantly affects adult males. Patients usually present with obstructive jaundice due to enlargement of the pancreatic head or thickening of the lower bile duct wall. Pancreatic cancer is the leading differential diagnosis for which serological, imaging, and histological examinations need to be considered. Serologically, an elevated level of IgG4 is the most sensitive and specific finding. Imaging features include irregular narrowing of the pancreatic duct, diffuse or focal enlargement of the pancreas, a peri-pancreatic capsule-like rim, and enhancement at the late phase of contrast-enhanced images. Biopsy or surgical specimens show diffuse lymphoplasmacytic infiltration containing many IgG4⁺ plasma cells, storiform fibrosis, and obliterative phlebitis. A dramatic response to steroid therapy is another characteristic, and serological or radiological effects are normally identified within the first 2 or 3 weeks. Type 1 AIP is estimated as a pancreatic manifestation of systemic IgG4-related disease based on the fact that synchronous or metachronous lesions can develop in multiple organs (e.g. bile duct, salivary/lacrimal glands, retroperitoneum, artery, lung, and kidney) and those lesions are histologically identical irrespective of the organ of origin. Several potential autoantigens have been identified so far. A Th2-dominant immune reaction and the activation of regulatory T-cells are assumed to be involved in the underlying immune reaction. IgG4 antibodies have two unique biological functions, Fab-arm exchange and a rheumatoid factor-like activity, both of which may play immune-defensive roles. However, the exact role of IgG4 in this disease still remains to be clarified. It seems important to recognize this unique entity given that the disease is treatable with steroids.

A case of IgG4-related disease with rectal cancer

A 72-year-old male with liver dysfunction and an increase in serum total protein/albumin (TP/Alb) ratio was referred to our hospital. There was a marked increase in serum immunoglobulin (Ig) G4 level (IgG/IgG4: 3,485/2,860 mg/dl). Diagnostic imaging did not reveal any enlargement of the pancreas or narrowing of the pancreatic duct. However, bilateral submaxillary gland swelling, sclerosing cholangitis, and retroperitoneal fibrosis were noted, suggesting multifocal fibrosclerosis. Histological examination of the submaxillary gland showed the infiltration of IgG4-positive plasma cells, although there was no narrowing of the pancreatic duct, leading to a diagnosis of IgG4-related disease with various extrapancreatic lesions. Systemic investigation before the introduction of steroid therapy revealed rectal cancer. After low-position anterior resection, steroid therapy was introduced, reducing the lesions. Recent studies have reported autoimmune pancreatitis/IgG4-related disease with malignant tumors. However, the association and pathogenesis remain to be clarified. Malignant tumors are detected before or after the treatment of autoimmune pancreatitis/IgG4-related disease; pretreatment diagnosis and post-treatment follow-up should be carefully performed, bearing in mind the concomitant development of malignant tumors.

Utility of FDG PET/CT in IgG4-related systemic disease

IgG4-related systemic disease (IgG4-RSD) is an emerging clinical entity about which much remains to be elucidated, in terms of its aetiology, pathogenesis, diagnosis, treatment and outcome. Autoimmune pancreatitis (AIP) and Mikulicz disease (MD) are the two major, well-studied constituents of IgG4-RSD. AIP and MD have common characteristics of forming tumour-mimicking lesions that consist of lymphoplasmacytic infiltrates and fibrosclerosis with numerous immunoglobulin G4 (IgG4)-positive plasma cells, as well as various multi-organ manifestations of IgG4-RSD. 2-[(18)F]-fluoro-2-deoxy-d-glucose positron-emission tomography/ computed tomography (FDG PET/CT) enables the acquisition of whole-body images and provides functional information about disease activity; as such it has a valuable role in staging extent of disease, guiding biopsy, and monitoring response to treatment. However, FDG PET/CT is likely to be only one component of the management strategy, and clinical, laboratory, imaging and histological findings are crucial in the overall diagnosis of the condition. At present FDG PET/CT does not have a well-established role in the assessment of patients with IgG4-RSD and future prospective studies are required to define the cost-effectiveness and clinical impact in this patient group more accurately.

Gastric emptying in patients with autoimmune pancreatitis

OBJECTIVES

Autoimmune pancreatitis (AIP) and its extrapancreatic lesions seem to be clinical manifestations of organs involved in IgG4-related systemic disease. To clarify whether the stomach is a target organ, gastric function was evaluated in patients with AIP.

METHODS

In 6 patients with AIP, gastric emptying was assessed by Carbon 13 (¹³C) acetate breath test before and after steroid therapy. Based on 4-hour breath samples, the half ¹³CO₂ excretion time (T(1/2)) and the time of maximal excretion (T(max)) were calculated as gastric emptying parameters. Data of 20 healthy volunteers were used as controls. The number of IgG4-positive plasma cells in gastrofiberscopic biopsy specimens was counted before and after steroid therapy.

RESULTS

Both T(1/2) and T(max) in patients with AIP decreased significantly after steroid therapy (T(1/2): 1.89 ± 0.21 hours vs 1.69 ± 0.15 hours, P = 0.046; and T(max): 1.1 ± 0.2 hours vs 0.96 ± 0.2 hours, P = 0.027), and became similar to those of the controls (T(1/2): 1.69 ± 0.32 hours and T(max): 0.98 ± 0.2 hour). The number of IgG4-positive plasma cells infiltrating the gastric mucosa decreased after steroid therapy.

CONCLUSIONS

Gastric emptying was impaired in patients with AIP and improved to the reference range after steroid therapy. The stomach may be a target organ of IgG4-related systemic disease.

Involvement of inducible costimulator- and interleukin 10-positive regulatory T cells in the development of IgG4-related autoimmune pancreatitis

OBJECTIVES

Immunoglobulin G4 (IgG4)-related autoimmune pancreatitis (AIP) is a new clinical entity of pancreatic disorder. There are immunologic and histological abnormalities, including increased serum IgG4 levels and the infiltration of IgG4-positive plasmacytes. However, the role of IgG4 is unclear. Recently, regulatory T cells (Tregs) were reported to contribute to the development of various autoimmune diseases as well as in B-cell shifting to IgG4-producing plasmacytes. We studied Tregs in the pancreas and peripheral blood.

METHODS

We recruited 44 patients with IgG4-related AIP. For comparison, we recruited 37 patients with other pancreatic diseases and 27 healthy subjects as controls. We studied infiltrating cells in the pancreas by immunohistochemistry and analyzed inducible costimulator-positive Tregs and interleukin 10-positive Tregs in the peripheral blood by flow cytometry.

RESULTS

The ratio of Foxp3-positive cells to infiltrated mononuclear cells (Foxp3/Mono) in AIP patients was significantly higher than in patients with alcoholic chronic pancreatitis. In AIP, Foxp3/Mono and IgG4/Mono were positively correlated. Inducible costimulator-positive Tregs were significantly higher in AIP patients than in the patients with other pancreatic diseases and the healthy control group. Interleukin 10-positive Tregs were significantly higher in AIP patients than in the healthy control group.

CONCLUSIONS

Increased quantities of inducible costimulator-positive Tregs may influence IgG4 production in IgG4-related AIP.

[IgG4-related systemic disease: emergence of a new systemic disease? Literature review]

Hyper-IgG4 syndrome, or IgG4-related systemic disease (IgG4-RSD), has been recently characterized by the association of a focal or diffuse enlargement in one or more organs, elevated levels of serum IgG4 and histopathological findings including "storiform" fibrosis and prominent infiltration of lymphocytes and IgG4-positive plasma cells. Pancreas was the first organ involved with sclerosing pancreatitis (or autoimmune pancreatitis). Since this first description, many extrapancreatic lesions have been described, even in the absence of pancreatitis and include sialadenitis, lacrimal gland inflammation, lymphadenopathy, aortitis, sclerosing cholangitis, tubulointerstitial nephritis, retroperitoneal fibrosis or inflammatory pseudotumors. Multiorgan lesions can occur synchronously or metachronously in a same patient, usually after 50 years of age. They all share common histopathological findings. The disease often responds well to corticosteroid therapy. In this literature review on IgG4-RSD, we present historical, epidemiological and clinical characteristics, and we review the biological and histological diagnostic criteria. To date there is no international validated diagnostic criteria. Pathophysiological hypothesis and therapeutic approaches are also discussed.

Autoimmune pancreatitis mimicking pancreatic cancer

BACKGROUND/PURPOSE

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that can often be difficult to distinguish from pancreatic cancer. We describe the clinical and radiographic features of 23 patients with AIP whose presentations mimicked pancreatic cancer.

METHODS

A review of clinic, radiology, and endoscopy records from a 6-year period identified patients with AIP initially suspected of having pancreatic cancer. Abdominal computed tomography (CT) with intravenous contrast, endoscopic ultrasonography (EUS), and/or ERCP was performed in each patient. The diagnosis of AIP was made histologically and/or cytologically for each patient.

RESULTS

Nineteen of 23 patients (83%) presented with new-onset weight loss, jaundice, or both. Nineteen (83%) patients had CT findings worrisome for pancreatic cancer including: (1) pancreatic enlargement or focal mass, (2) regional lymphadenopathy, and/or (3) vascular invasion. Eighteen patients (78%) had common bile duct strictures on ERCP. EUS-guided fine-needle aspiration biopsies excluded pancreatic cancer in all 22 patients who had EUS (96%). Seven patients had surgery for continued suspicion of pancreatic cancer.

CONCLUSIONS

Although AIP commonly presents with features suggestive of pancreatic cancer, clinical recognition of AIP with appropriate diagnostic testing including EUS with fine-needle aspiration, ERCP, IgG4 levels, and pancreatic protocol CT expedites diagnosis and can spare patients unnecessary surgery.

Cure of alopecia areata after eradication of Helicobacter pylori: a new association?

Alopecia areata is a disease of the hair follicles, with strong evidence supporting autoimmune etiology. Alopecia areata is frequently associated with immune-mediated diseases with skin manifestations such as psoriasis and lichen planus, or without skin manifestations such as autoimmune thyroiditis and idiopathic thrombocytopenic purpura. Helicobacter pylori (H. pylori) infection is present in around 50% of the world's population and has been associated with a variety of immune-mediated extra-digestive disorders including autoimmune thyroiditis, idiopathic thrombocytopenic purpura, and psoriasis. A case of a 43-year old man with an 8-mo history of alopecia areata of the scalp and beard is presented. The patient was being treated by a dermatologist and had psychiatric support, without any improvement. He had a history of dyspepsia and the urea breath test confirmed H. pylori infection. The patient went into remission from alopecia areata after H. pylori eradication. If such an association is confirmed by epidemiological studies designed for this purpose, new therapeutic options could be available for these patients, especially in areas where infection with H. pylori is highly prevalent.

Are dysregulated inflammatory responses to commensal bacteria involved in the pathogenesis of hepatobiliary-pancreatic autoimmune disease? An analysis using mice models of primary biliary cirrhosis and autoimmune pancreatitis

The etiopathogenesis of many autoimmune disorders has not been identified. The aim of this paper is to focus on the involvement of bacterial exposure in the pathogenesis of primary biliary cirrhosis (PBC) and autoimmune pancreatitis (AIP), both of which are broadly categorized as autoimmune disorders involving hepatobiliary-pancreatic lesions. Avirulent and/or commensal bacteria, which may have important role(s) as initiating factors in the pathogenesis of autoimmune disorders such as PBC and AIP, will be emphasized.

Autoimmune pancreatitis: pancreatic and extrapancreatic MR imaging-MR cholangiopancreatography findings at diagnosis, after steroid therapy, and at recurrence

PURPOSE

To determine and describe the magnetic resonance (MR) imaging-MR cholangiopancreatographic pancreatic and extrapancreatic findings of autoimmune pancreatitis (AIP) and the probability, site, and MR features of recurrent AIP after steroid therapy.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board, and the requirement for informed patient consent was waived. The data of 27 patients with AIP were included in the study. All patients had undergone MR imaging with MR cholangiopancreatography before and after steroid treatment and during follow-up (median follow-up period, 45 months). Image analysis included assessment of pancreatic parenchyma enlargement, signal intensity on T1- and T2-weighted MR images, contrast enhancement, and presence of bile duct and/or renal involvement. The probability of AIP recurrence was assessed by using Kaplan-Meier curves and the unadjusted Cox model.

RESULTS

At the time of diagnosis, the AIP-affected pancreatic parenchyma showed diffuse enlargement in 14 (52%) of the 27 patients and segmental enlargement in 13 (48%). The pancreatic parenchyma appeared hypointense on T1-weighted images in all 27 (100%) patients, hyperintense on T2-weighted images in 25 (93%), and isointense in two (7%). During the pancreatic phase of the dynamic contrast material-enhanced study, the affected pancreatic parenchyma appeared hypointense in 25 (93%) patients and isointense in two (7%). During the portal venous and delayed phases, the images of 19 (70%) patients showed delayed enhancement. Bile duct involvement was observed in 10 (37%) patients, and renal involvement was observed in two (7%). After steroid treatment, six (22%) patients had recurrent AIP, with a median disease-free interval of 20.6 months. The sites of recurrence were the pancreas and the kidneys in three of the six patients, solely the pancreas in two patients, and the biliary ducts in one patient.

CONCLUSION

MR imaging with MR cholangiopancreatography enables the diagnosis of pancreatic and extrapancreatic AIP and the assessment of changes after steroid therapy.

Sclerosing nodular lesions of the gastrointestinal tract containing large numbers of IgG4 plasma cells

BACKGROUND

Hyalinised fibrous nodules have been encountered within the gastrointestinal tract (GIT) and been labelled as reactive nodular fibrous tumours. Several have a history of abdominal surgery and/or sepsis that acts as a precipitating cause for the fibrosis. Recently, much attention has been focused on IgG4 related fibrosing lesions that are typically associated with a high population of IgG4 positive plasma cells and tissue fibrosis. There may be attendant elevated serum IgG4 levels and associated autoimmune disease.

METHODS

We present four patients with well-circumscribed fibrous nodular lesions occurring in the GIT. Tissue was formalin fixed after microwave antigen retrieval and H&E stains and immunohistochemistry were performed. IgG4/IgG ratios were calculated from the three high power fields containing the densest concentration of positive plasma cells.

RESULTS

The patients were two females (45 and 56 years) and two males (47 and 60 years) who presented with gastric (2 cases), caecal and sigmoid flexure involvement. One case had four lesions while the other three cases were solitary nodules. Two patients had coexistent autoimmune disease. All lesions were nodular and composed of paucicellular, hyalinised fibrous tissue associated with chronic inflammation. In all lesions the plasma cell population was strongly IgG4 positive.

CONCLUSIONS

This paper describes unique, well-circumscribed sclerosing nodules containing IgG4 positive plasma cells within the bowel wall that may cause mucosal polypoid lesions. It is possible that these lesions may be related to the spectrum of IgG4 related sclerosing disease or belong to a separate subset of inflammatory reactive conditions that are rich in IgG4 plasma cells.

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.

Pathogenesis of IgG4-related disease

PURPOSE OF REVIEW

To review studies that have examined underlying genetic and immunological aspects of IgG4-related disease.

RECENT FINDINGS

Genetic studies have suggested that several human leukocyte antigen (HLA) and non-HLA haplotypes/genotypes are associated with susceptibility to IgG4-related disease or to disease relapse after steroid therapy. Among several autoantibodies identified so far, autoantibodies against lactoferrin and carbonic anhydrase II are most frequently detected in serum of IgG4-disease patients. However, it has not been well clarified whether or not those autoantibodies belong to an IgG4 subclass. Studies that have demonstrated molecular mimicry between Helicobacter pylori and constituents of pancreatic epithelial cells suggest that gastric H. pylori infection triggers autoimmune pancreatitis in genetically predisposed individuals through antibody cross-reactivity. Recently, T-helper 2 immune reaction has been suggested to be predominant in IgG4-related disease. Interestingly, regulatory immune reactions are activated in IgG4-related disease, and regulatory cytokines interleukin-10 and transforming growth factor-b have been suggested, respectively, to play important roles in IgG4 class switch and fibroplasia.

SUMMARY

Autoimmunity has been considered the most probable pathogenesis of IgG4-related disease, but has not been completely proved so far. A breakthrough study to detect a specific autoantigen, autoantibody, or pathogen is necessary.

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.

Potential value of serum total IgE for differentiation between autoimmune pancreatitis and pancreatic cancer

Autoimmune pancreatitis (AIP) is associated with a marked elevation of serum total IgG₄ . Although there is evidence of autoimmunity in AIP, there are also signs of an allergic nature of its pathogenesis. Therefore, we determined both IgE and IgG₄ in 13 patients with AIP, in 12 patients with pancreatic carcinoma and in 14 patients with atopic allergy and investigated the relationship between IgE and IgG₄ . Total IgG₄ was determined by automated nephelometry and total IgE by automated enzyme fluoroimmunoassay. Both total IgE and total IgG₄ levels in patients with AIP were significantly higher than those in patients with pancreatic carcinoma (P = 0.0004 and P = 0.015, respectively). There was a significant correlation between the total IgE and total IgG₄ levels in patients with AIP and patients with atopic allergy (r(s) =0.82, P=0.0006 and r(s) =0.88, P < 0.0001, respectively). The IgE/ IgG₄ ratio in sera from patients with atopic allergy was significantly different (P = 0.0012) from this ratio in sera from patients with AIP. These results suggest that analysis of total IgE in serum might be useful in the differentiation between autoimmune pancreatitis and pancreatic carcinoma.

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.

Clinical analysis of high serum IgE in autoimmune pancreatitis

AIM: To clarify the clinical significance of high serum IgE in autoimmune pancreatitis (AIP).

METHODS: Forty-two AIP patients, whose IgE was measured before steroid treatment, were analyzed. To evaluate the relationship between IgE levels and the disease activity of AIP, we examined (1) Frequency of high IgE (> 170 IU/mL) and concomitant allergic diseases requiring treatment; (2) Correlations between IgG, IgG4, and IgE; (3) Relationship between the presence of extrapancreatic lesions and IgE; (4) Relationship between clinical relapse and IgE in patients treated with steroids, and (5) Transition of IgE before and after steroid treatment.

RESULTS: IgE was elevated in 36/42 (86%) patients. Concomitant allergic disease was observed in seven patients (allergic rhinitis in three, bronchial asthma in three, and urticaria in one). There were no significant correlations between IgG, IgG4, and IgE (r = -0.168 for IgG, and r = -0.188 for IgG4). There was no significant difference in IgE in the patients with and without extrapancreatic lesions (526 ± 531 IU/mL vs 819 ± 768 IU/mL, P = 0.163), with and without clinical relapse (457 ± 346 IU/mL vs 784 ± 786 IU/mL, P = 0.374). There was no significant difference in IgE between before and after steroid treatment (723 ± 744 IU/mL vs 673 ± 660 IU/mL, P = 0.633).

CONCLUSION: Although IgE does not necessarily reflect the disease activity, IgE might be useful for the diagnosis of AIP in an inactive stage.

IgG4-related sclerosing disease: a critical appraisal of an evolving clinicopathologic entity

An elevated serum titer of immunoglobulin G4 (IgG4), the least common (3% to 6%) of the 4 subclasses of IgG, is a surrogate marker for the recently characterized IgG4-related sclerosing disease. The syndrome affects predominantly middle-aged and elderly patients, with male predominance. The patients present with symptoms referable to the involvement of 1 or more sites, usually in the form of mass lesions. The prototype is IgG4-related sclerosing pancreatitis (also known as autoimmune pancreatitis), most commonly presenting as painless obstructive jaundice with or without a pancreatic mass. Other common sites of involvement are the hepatobiliary tract, salivary gland, orbit, and lymph node, but practically any organ-site can be affected, such as retroperitoneum, aorta, mediastinum, soft tissue, skin, central nervous system, breast, kidney, prostate, upper aerodigestive tract, and lung. The patients usually have a good general condition, with no fever or constitutional symptoms. Common laboratory findings include raised serum globulin, IgG, IgG4, and IgE, whereas lactate dehydrogenase is usually not raised. Some patients have low titers of autoantibodies (such as antinuclear antibodies and rheumatoid factor). The disease often shows excellent response to steroid therapy. The natural history is characterized by the development of multiple sites of involvement with time, sometimes after many years. However, the disease can remain localized to 1 site in occasional patients. The main pathologic findings in various extranodal sites include lymphoplasmacytic infiltration, lymphoid follicle formation, sclerosis and obliterative phlebitis, accompanied by atrophy and loss of the specialized structures of the involved tissue (such as secretory acini in pancreas, salivary gland, or lacrimal gland). The relative predominance of the lymphoplasmacytic and sclerotic components results in 3 histologic patterns: pseudolymphomatous, mixed, and sclerosing. Immunostaining shows increased IgG4+ cells in the involved tissues (>50 per high-power field, with IgG4/IgG ratio >40%). The lymph nodes show multicentric Castleman disease-like features, reactive follicular hyperplasia, interfollicular expansion, or progressive transformation of germinal centers, with the unifying feature being an increase in IgG4+ plasma cells on immunostaining. The nature and pathogenesis of IgG4-related sclerosing disease are still elusive. Occasionally, the disease can be complicated by the development of malignant lymphoma and possibly carcinoma.

Analysis of regulatory T cells and IgG4-positive plasma cells among patients of IgG4-related sclerosing cholangitis and autoimmune liver diseases

OBJECTIVES

Patients with autoimmune pancreatitis (AIP) characteristically show elevated serum levels of immunoglobulin G4 (IgG4) and abundant infiltration of IgG4-positive plasmacytes in the involved organs. The most common involved organ showing extrapancreatic lesions is the bile duct, which exhibits sclerosing cholangitis (SC). However, the role of IgG4 in the development of IgG4-related SC (IgG4-SC) remains unclear. To clarify the role of IgG4 in IgG4-SC, we have performed an immunohistochemical analysis of the bile duct.

METHODS

Laboratory and immunohistochemical findings of liver biopsy specimens obtained from patients with IgG4-SC, primary sclerosing cholangitis (PSC), autoimmune hepatitis (AIH), and primary biliary cirrhosis (PBC) were compared. The biopsy specimens were first stained with anti-IgG1, anti-IgG4, and anti-Foxp3 (forkhead box P3) antibodies, and the ratio of IgG4-, IgG1-, and Foxp3-positive cells, respectively, to infiltrated mononuclear cells (IgG4/Mono, IgG1/Mono, Foxp3/Mono) was assessed.

RESULTS

The ratio of IgG4/IgG1-positive plasma cells was significantly higher in specimens obtained from patients with IgG4-SC than in those from patients with PSC, AIH, and PBC. The Foxp3/Mono ratio in patients with PBC was significantly higher than that in patients with IgG4-SC and PSC. In patients with IgG4-SC, the number of Foxp3-positive cells was significantly correlated with the number of IgG4-positive cells; in the other patient groups, there was no correlation.

CONCLUSIONS

The IgG4/IgG1 ratio in the liver may be a useful marker for differential diagnosis of IgG4-SC and PSC. In IgG4-SC, abundant infiltration of regulatory T cells (Tregs) may affect the switching of B cells to IgG4-producing plasmacytes, and there is a possibility that the function of Tregs is different in IgG4-SC and other liver diseases (PSC, AIH, and PBC).

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.

K-ras mutation in the major duodenal papilla and gastric and colonic mucosa in patients with autoimmune pancreatitis

BACKGROUND

Pancreatic cancer occurs in some patients with autoimmune pancreatitis (AIP). Significant K-ras mutations are frequently detected in the pancreas of AIP patients. AIP may be a pancreatic lesion of IgG4-related systemic disease. Gastric and colonic cancer can occur during the follow up of AIP patients. We examined K-ras mutations in the major duodenal papilla and gastric and colonic mucosa of AIP patients.

METHODS

K-ras analysis and/or immunohistochemical study was performed on the tissues of the major duodenal papilla (n = 8), gastric mucosa (n = 5), colonic mucosa (n = 3), pancreas (n = 5), common bile duct (n = 5), and gallbladder (n = 4) of 12 AIP patients.

RESULTS

Significant K-ras mutations were detected in the major duodenal papilla of 4 of 8 cases [GAT (n = 4)], in the gastric mucosa of 2 of 4 cases [AGT (n = 2)], and in the colonic mucosa of 2 of 3 cases [GAT (n = 2)]. Significant K-ras mutations were detected in the pancreas of all 5 cases [GAT (n = 5), in the common bile duct of 4 cases (GAT (n = 2), TGT (n = 1), and GCT/TGT (n = 1)], and in the gallbladder epithelium of 3 cases [GAT (n = 1), GCT (n = 1), and GTT (n = 1)]. K-ras mutations were detected in the organs associated with IgG4-related fibroinflammation with abundant infiltration of T lymphocytes and forkhead box P3-positive cells.

CONCLUSIONS

Significant K-ras mutations were frequently detected in the major duodenal papilla and gastric and colonic mucosa of AIP patients. AIP patients may have risk factors for gastric and colonic cancer, but the mechanisms of K-ras mutation and its clinical implications are not clear.

The combined measurement of total serum IgG and IgG4 may increase diagnostic sensitivity for autoimmune pancreatitis without sacrificing specificity, compared with IgG4 alone

OBJECTIVES

Until now, there was no international consensus on the diagnostic criteria for autoimmune pancreatitis (AIP). As for serologic criteria, the HISORt criteria use elevated immunoglobulin (Ig) G4 alone, whereas the Asian diagnostic criteria include elevations of total IgG or IgG4, or the presence of autoantibodies. This study was mainly aimed at determining whether the combined measurement of total IgG and IgG4 could increase the diagnostic sensitivity for AIP while maintaining specificity, compared with IgG4 alone. Another aim was to determine the utility of autoantibodies to diagnose AIP.

METHODS

We prospectively measured total serum IgG and IgG4 together in 82 consecutive patients with AIP, and seropositivity was defined as elevation of either total IgG or IgG4. To evaluate specificity in the differentiation of AIP from pancreatic cancer, total serum IgG and IgG4 were prospectively measured in 110 patients with pancreatic cancer. Also, the detection rates of antinuclear antibody (ANA) and rheumatoid factor (RF) were retrospectively reviewed in patients with AIP.

RESULTS

In patients with AIP, the sensitivity of IgG4 (> or = 135 mg/dl) was 52.5% (43/82), significantly higher than that (46.3%, 38/82) of total IgG (> or = 1,800 mg/dl) (P<0.05). The sensitivity of combined measurement of total IgG and IgG4 for AIP was 68.3% (56/82), significantly higher than that of IgG4 alone (P<0.05). The specificity of total IgG and IgG4 in the differentiation of AIP from pancreatic cancer was 96.4 and 99.1%, respectively. The specificity of combined measurement of total IgG and IgG4 was 95.5%, and it was not significantly different from that of IgG4 alone (P=0.125). The sensitivity of ANA (> or = 1:80) and RF was 24.4% (19/78) and 20.3% (13/64), respectively. All but one patient who had positive results for ANA or RF also showed elevations of either total IgG or IgG4, respectively.

CONCLUSIONS

The combined measurement of total serum IgG and IgG4 may increase diagnostic sensitivity without sacrificing specificity, compared with IgG4 alone. However, the measurement of ANA or RF may show no additional benefit when combined with total serum IgG and IgG4.

Autoimmune pancreatitis

Autoimmune pancreatitis is becoming a more widely recognized form of pancreatitis that can mimic pancreatic or biliary malignancy. The combination of serological, histological and radiographic findings makes it unique among pancreatic diseases. The presence of autoantibodies, IgG4 and a lymphoplasmacytic infiltrate reflect its autoimmune etiology. The dramatic response to steroids is also a distinguishing feature and differentiates it from other pancreatic diseases.

Exocrine and endocrine pancreatic function in 21 patients suffering from autoimmune pancreatitis before and after steroid treatment

BACKGROUND/AIM

Autoimmune pancreatitis (AIP) responds rapidly and dramatically to steroid therapy. The aim of this study was to evaluate pancreatic exocrine and endocrine function in patients suffering from AIP both before and after steroid therapy.

PATIENTS AND METHODS

Fecal elastase 1 and diabetes were evaluated before steroid therapy and within 1 month of its suspension in 21 patients (13 males and 8 females, mean age 43 +/- 16.5 years) diagnosed as having AIP between 2006 and 2008.

RESULTS

At clinical onset, fecal elastase 1 was 107 +/- 126 microg/g stool. Thirteen patients (62%) showed severe pancreatic insufficiency (<100 microg/g stool), 4 (19%) had mild insufficiency (100-200 microg/g stool), while 4 (19%) had normal pancreatic function (>200 microg/g stool). Before steroids, diabetes was diagnosed in 5 patients (24%), all of whom had very low levels of fecal elastase 1 (<19 microg/g stool). Following steroids, fecal elastase 1 increased in all patients (237 +/- 193 microg/g stool) and observed levels were significantly higher than those seen before steroids (p = 0.001).

CONCLUSIONS

Patients suffering from AIP display exocrine and/or endocrine pancreatic insufficiency at clinical onset. These insufficiencies improve after steroid therapy.

The birthday of a new syndrome: IgG4-related diseases constitute a clinical entity

IgG4-related disease is a distinct clinical entity, whose characteristic features are the following; Serum IgG4 is prominently elevated, IgG4-positive plasma cells infiltrate in involved tissues, various mass-forming lesions with fibrosis develop in a timely and spatial manner and the response to corticosteroids is prompt and good. IgG4-related diseases mainly target two organs. One is the pancreas (autoimmune pancreatitis; AIP), and the other comprises the lacrimal and salivary glands, the clinical phenotype is Mikulicz's disease (MD). MD has long been considered a manifestation of Sjögren's syndrome (SS). However, we noticed several clinical differences in case of MD from SS; no deflection of female sex differences, mild sicca syndrome, good response to corticosteroids, no positivity of anti-SS-A/SS-B antibodies. In addition, elevated level of serum IgG4 and abundant infiltration of plasma cells expressing IgG4 were reported in MD patients. Those are common features of IgG4-related diseases. MD often coexisted with IgG4-related diseases such as AIP, retroperitoneal fibrosis, and IgG4-associated nephropathy. Based on those findings, it has been considered to recognize IgG4-related diseases including MD as a new clinical entity. The etiology of IgG4-related systemic diseases remains to be elucidated. It is necessary to accumulate and analyze larger data from patients worldwide.

Refractory gastric ulcer with abundant IgG4-positive plasma cell infiltration: A case report

We describe a 77-year-old man with refractory gastric ulcer that worsened after Helicobacter pylori eradication therapy. Pathology showed marked infiltration of IgG4-positive plasma cells in the gastric lesions, which led us to suspect IgG4-related sclerosing disease. To the best of our knowledge, this is the first report of IgG4-related gastric ulcer without the main manifestation of autoimmune pancreatitis.

Decreased production of immunoglobulin M and A in autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis (AIP) is a rare type of chronic pancreatitis caused by an autoimmune abnormality. It is well known that high serum concentrations of IgG4 are helpful for making a diagnosis of AIP; however, it is unclear whether there are abnormalities in the production of other immunoglobulins in AIP.

METHODS

We examined the immune condition of AIP patients before and after glucocorticoid treatment, focusing on serum levels of IgG, IgG4, IgM and IgA, and compared the results with those in other hepato-pancreatic diseases, such as autoimmune hepatitis, primary biliary cirrhosis, chronic pancreatitis and pancreatic carcinoma.

RESULTS

IgM and IgA were decreased in patients with untreated AIP. IgM and IgG or IgG4 were negatively correlated in patients with AIP. The ratios of IgG to IgM and IgG to IgA in patients with AIP were significantly increased compared with the other diseases. The diagnostic sensitivity of IgG to IgM and IgG to IgA was 0.800 and 0.950, and the specificity of each ratio was 0.703 and 0.728, respectively, in the differentiation of AIP from the other diseases. IgM was not significantly changed after glucocorticoid treatment in the patients with AIP, while IgG, IgG4 and IgA decreased.

CONCLUSIONS

The ratios of IgG to IgM and IgG to IgA may serve as novel diagnostic markers to differentiate AIP from other hepato-pancreatic diseases. Furthermore, low concentrations of IgM and IgA may be involved in the pathogenesis of AIP.

-651C/T promoter polymorphism in the CD14 gene is associated with severity of acute pancreatitis in Japan

PURPOSE

This study aimed to clarify the association of the promoter variants in the CD14 gene with pancreatic diseases in Japan.

METHODS

Three hundred forty-six unrelated patients with acute pancreatitis (AP) (107 with severe and 239 with mild), 263 patients with chronic pancreatitis (CP), 264 patients with pancreatic neoplasm, and 319 healthy controls were genotyped for the single nucleotide polymorphisms at positions -260 and -651 from the AUG start codon in the CD14 gene by polymerase chain reaction-restriction enzyme digestion.

RESULTS

The allele and genotype frequencies of the -260C/T and -651C/T polymorphisms did not differ between controls and patients with AP. In subgroup analyses, patients with severe AP had more -651C allele than controls [P = 0.005; odds ratio (OR) 1.71; 95% confidence interval (CI) = 1.18-2.49] or patients with mild AP (P = 0.001; OR 1.95; 95% CI = 1.33-2.85). Genotype -651CC was more common (P = 0.001 vs. controls and P = 0.001 vs. mild AP), and -651CT was less (P = 0.009 vs. controls and P = 0.007 vs. mild AP) in patients with severe AP than in healthy controls or patients with mild AP. The frequencies of pseudocyst development and requirement of surgery were higher in AP patients with -651CC than in those without this genotype. The -260C/T polymorphism was not associated with the severity of AP. The allele and genotype frequencies of both polymorphisms did not differ between controls and patients with CP or pancreatic neoplasm.

CONCLUSION

-651C/T promoter polymorphism in the CD14 gene was associated with severity of AP in Japan.

Diabetes associated with autoimmune pancreatitis: new insights into the mechanism of β-cell dysfunction

A high proportion of patients with autoimmune pancreatitis (AIP) have diabetes. The decreased β-cell function in active AIP, which leads to diabetes, can sometimes be reversed by corticosteroid treatment. However, the immunological mechanisms causing this β-cell dysfunction are largely unclear. Our recent studies on AIP complicated with diabetes, and data from other animal models of AIP, suggest the presence of distinct mechanisms responsible for β-cell damage in AIP. The presence of immunological cross-reactivity against antigens that are localized both in exocrine pancreatic tissue and β-cells may explain the concomitant occurrence of pancreatitis and β-cell damage in AIP.

Is (18)F-fluorodeoxyglucose positron emission tomography meaningful for estimating the efficacy of corticosteroid therapy in patients with autoimmune pancreatitis?

BACKGROUND

Autoimmune pancreatitis (AIP) is often misdiagnosed as pancreatic cancer (PC). Both conditions accumulate (18)F-fluorodeoxyglucose (FDG), so FDG positron emission tomography (FDG-PET) is not discriminatory. This study aimed to evaluate the pattern of FDG accumulation, and the change in FDG uptake after steroid treatment in AIP and PC.

METHODS

We compared FDG-PET patterns between 18 patients with AIP and 20 patients with PC, and also evaluated the short-term changes in FDG uptake after steroid therapy.

RESULTS

FDG uptake was observed in 88.9% in AIP and 90.0% in PC. FDG uptake in extra-abdominal lymph nodes was seen more frequently in AIP, and uptake in salivary glands, eyes and biliary ducts was seen only in AIP. Follow-up PET was performed in 6 AIP patients and in 3 PC patients. Changes in SUV(max) after steroid therapy were estimated within 1 week in 5 AIP patients and in all 3 PC patients, retrospectively. In 4 AIP patients, the change in SUV(max) was more than 10%. On the other hand, in PC, SUV(max) increased or remained almost unchanged (within 10%).

CONCLUSIONS

FDG-PET pattern at baseline, and a decrease in FDG uptake after a short steroid trial can be useful for discriminating AIP from PC.

[From the chronic pancreatitis to chronic pancreatites]

Chronic alcohol intake accounts for 60-90% of the cases of chronic pancreatitis, but other etiologies have been recognized and described in the very recent years. Genetic causes include mutations of the cationic trypsinogen gene PRSS1 (100 families in France), of its inhibitor SPINK1 and of the CFTR gene involved in cystic fibrosis. Auto-immune pancreatitis is often part of an "IgG4-related systemic disease" involving the biliary tract, the salivary glands, the retroperitoneum and/or the kidneys. Diagnostic criteria are now well-defined (HISORt of the Mayo Clinic), with ductal and parenchymal lesions on imaging that may mimick pancreatic adenocarcinoma. Corticoids are efficacious but recurrences are frequent and long-term outcome is still poorly known.

Toll-like receptor 3 signaling induces chronic pancreatitis through the Fas/Fas ligand-mediated cytotoxicity

Innate immunity plays important roles in host defense against pathogens, but may also contribute to the development of autoimmune diseases under certain conditions. Toll-like receptors (TLRs) recognize various pathogens and induce innate immunity. We herein present a mouse model for chronic pancreatitis, which was induced by TLR3 signaling that generated the Fas/Fas ligand (FasL)-mediated cytotoxicity. An analogue of viral double-stranded RNA, polyinosinic:polycytidylic acid (poly I:C), which is recognized by TLR3, was injected into autoimmune-prone strains: MRL/Mp mice (MRL/+), MRL/Mp mice with a deficit of Fas (MRL/lpr) and MRL/Mp mice with a deficit of functional FasL (MRL/gld). The pancreatitis in MRL/+ mice was initiated by the destruction of pancreatic ductules, and its severity was significantly higher than that in MRL/lpr mice or MRL/gld mice. Using a pancreatic duct epithelial cell line MRL/S-1 newly established from the MRL/gld mouse that lacks FasL, we showed that treatment with poly I:C significantly induced the expression of Fas on the cultured cells. MRL/S-1 cells were destructed when co-cultured with splenocytes bearing intact FasL prepared from MRL/+ or MRL/lpr mice, but the magnitude of cytotoxicity was smaller with splenocytes of MRL/gld mice. Likewise, synthetic FasL protein showed cytotoxicity on MRL/S-1 cells. Furthermore, MRL/S-1 cells expressed higher levels of chemokines after the treatment with poly I:C, suggesting that the poly I:C-mediated induction of chemokines may be responsible for recruitment of lymphoid cells to the pancreatic periductular regions. These findings indicate that TLR3 signaling generates the Fas/FasL-mediated cytotoxicity, thereby leading to the development of chronic pancreatitis.

Interferon-gamma treatment accelerates and aggravates autoimmune pancreatitis in the MRL/Mp-mouse

BACKGROUND

T helper 1 cell-released pro-inflammatory cytokines have been implicated in the pathogenesis of autoimmune pancreatitis (AIP), but the experimental database is small. Here, we have directly tested the effects of interferon-gamma (IFN-gamma) by applying it to AIP-prone MRL/Mp mice.

METHODS

MRL/Mp-mice were treated for 4 weeks with IFN-gamma. Severity of AIP was assessed by histopathology, laboratory findings and gene expression analysis.

RESULTS

Using a histopathological score from 0 (healthy pancreas) to 4 (severe AIP), we found that IFN-gamma treatment strongly increased severity of pancreatic lesions. IFN-gamma also caused pancreatic accumulation of CD4-, CD8-, C11b- and CD138-positive cells, and enhanced pancreatic mRNA expression of interleukin (IL)-1 beta, transforming growth factor-beta and IFN-gamma itself. In the serum of IFN-gamma-treated mice, higher lipase activities but normal glucose levels were observed.

DISCUSSION

IFN-gamma accelerates and aggravates AIP in MRL/Mp mice. IFN-gamma-enhanced AIP of MRL/Mp mice may serve to study pathophysiology, and to test diagnostic/therapeutic approaches.

A case of pancreatic carcinoma with suspected autoimmune pancreatitis

We present a case of pancreatic carcinoma with strongly suspected coexisting autoimmune pancreatitis (AIP). The patient presented with a chief complaint of icterus and weight loss, and was referred to our institution after a pancreatic lesion was found. Blood test showed elevation of serum bilirubin, hepato-biliary enzyme, glucose and tumor markers, and also high levels of serum IgG4 (344 mg/dl, normal 4.8-105 mg/dl) and anti-DNA antibody (14 IU/ml, normal <6.0 IU/ml). Ultrasonography demonstrated an enlarged pancreas with smooth borders and low internal echo density. Enhanced computed tomography (CT) showed a sausage-shaped pancreas without definitive metastasis to the surrounding lymph nodes and liver. Imaging of the pancreatic duct, including endoscopic retrograde pancreatography (ERP) and magnetic resonance cholangiopancreatography (MRCP), showed stenosis of the main pancreatic duct at the pancreatic head as well as a long segment of narrowing at the body and no dilatation at the tail. Tissues from these stenotic sites and open biopsy from pancreatic body showed infiltrating adenocarcinoma and dense fibrosis. To date, only a small number of reports have described pancreatic carcinoma accompanied with AIP. It is important to confirm diagnosis with histology in cases of suspicious autoimmune pancreatitis, even when the clinical images are compatible with AIP.