Review of 67 patients with autoimmune pancreatitis in Korea: a multicenter nationwide study

Challenges for clinicians treating autoimmune pancreatitis: Current perspectives

Autoimmune pancreatitis (AIP) is a rare disease clinically characterized by obstructive jaundice, unintentional weight loss, acute pancreatitis, focal pancreatic mass, and diabetes. AIP is classified into two subtypes - type 1 and type 2 - according to pathological findings, clinical features, and serology test results, but some cases may be defined as type not otherwise in the absence of pathological findings and inflammatory bowel disease. To address the differences in diagnostic criteria by country, standard diagnostic criteria for AIP were proposed in 2011 by an international consensus of expert opinions. Differential diagnosis of AIP from pancreatic ductal adenocarcinoma is important but remains challenging for clinicians. Fortunately, all subtypes of AIP show dramatic response to steroid treatment. This review discusses the current perspectives on the diagnosis and management of AIP in clinical practice.

Current status of type 1 (IgG4-related) autoimmune pancreatitis

In 1995, Yoshida et al. proposed first the concept of "autoimmune pancreatitis" (AIP). Since then, AIP has been accepted as a new pancreatic inflammatory disease and is now divided two subtypes. Type 1 AIP affected immunoglobulin G4 (IgG4) and implicates the pancreatic manifestation of IgG4-related disease, while type 2 is characterized by neutrophil infiltration and granulocytic epithelial lesions (GEL). Recent research has clarified the clinical and pathophysiological aspects of type 1 AIP, which is more than type 2 among the Japanese population. However, many details remain unclear about the pathogenesis and progression of this disease. In this review, we discuss the current knowledge and recent advances relating to type 1 AIP.

Autoimmune Pancreatitis and Immunoglobulin G4-related Sclerosing Cholangitis: Past, Present, and Future

The emergence of glucocorticoid-responsive autoimmune pancreatitis (AIP) and IgG4-related sclerosing cholangitis (IgG4-SC), a new disease entity, has attracted considerable interest within the international gastroenterology community. The typical manifestations of AIP/IgG4-SC are obstructive jaundice and pancreatic enlargement in the elderly, which may mimic the presentations of pancreatobiliary malignancies. The timely diagnosis of AIP/IgG4-SC can lead to adequate glucocorticoid treatment, whereas a misdiagnosis can result in unnecessary major surgery. The diagnostic criteria used to diagnose AIP include several cardinal features of AIP that can be detected via pancreatic parenchymal imaging, ductal imaging, serum IgG4 levels, histopathology, other organ involvement, and response to glucocorticoid therapy. The differential diagnosis of AIP/IgG4-SC may include pancreatobiliary malignancies and primary sclerosing cholangitis. Although most patients with AIP/IgG4-SC respond well to glucocorticoid therapy, there is a frequent relapse of the disease in the long term. This review describes the evolution of the concept of AIP and IgG4-related disease, including the development of diagnostic criteria, discusses the current practice for diagnosis and treatment, and suggests prospects for research.

The Clinical Utility of Soluble Serum Biomarkers in Autoimmune Pancreatitis: A Systematic Review

Autoimmune pancreatitis (AIP) is a rare etiological type of chronic pancreatitis. The clinical and radiological presentation of AIP often resembles that of pancreatic cancer. Identifying non-invasive markers for their early distinction is of utmost importance to avoid unnecessary surgery or a delay in steroid therapy. Thus, this systematic review was conducted to revisit all current evidence on the clinical utility of different serum biomarkers in diagnosing AIP, distinguishing AIP from pancreatic cancer, and predicting disease course, steroid therapy response, and relapse. A systematic review was performed for articles published up to August 2021 by searching electronic databases such as MEDLINE, Web of Science, and EMBASE. Among 5123 identified records, 92 studies were included in the qualitative synthesis. Apart from immunoglobulin (Ig) G4, which was by far the most studied biomarker, we identified autoantibodies against the following: lactoferrin, carboanhydrase II, plasminogen-binding protein, amylase-α2A, cationic (PRSS1) and anionic (PRSS2) trypsinogens, pancreatic secretory trypsin inhibitor (PSTI/SPINK1), and type IV collagen. The identified novel autoantigens were laminin 511, annexin A11, HSP-10, and prohibitin. Other biomarkers included cytokines, decreased complement levels, circulating immune complexes, N-glycan profile changes, aberrant miRNAs expression, decreased IgA and IgM levels, increased IgE levels and/or peripheral eosinophil count, and changes in apolipoprotein isoforms levels. To our knowledge, this is the first systematic review that addresses biomarkers in AIP. Evolving research has recognized numerous biomarkers that could help elucidate the pathophysiological mechanisms of AIP, bringing us closer to AIP diagnosis and its preoperative distinction from pancreatic cancer.

Incidence of endocrine and exocrine insufficiency in patients with autoimmune pancreatitis at diagnosis and after treatment: a systematic review and meta-analysis

BACKGROUND

Autoimmune pancreatitis (AIP) is a rare form of pancreatitis that may lead to endocrine and exocrine insufficiency if left untreated. AIP clinically responds to glucocorticoids (GCs) therapy, but multiple GCs courses are often required to maintain remission with detrimental effects on glycaemic control.

OBJECTIVE

In this systematic review and meta-analysis, we aimed to assess the rate of endocrine and of exocrine insufficiency at diagnosis and at follow up in patients with AIP as well as the impact of GC therapy on pancreatic function in the long-term.

METHODS

The MEDLINE, SCOPUS, and EMBASE databases were searched from inception to August 2021 to identify studies reporting data on endocrine and exocrine insufficiency in patients with AIP. Pooled events were calculated using a random-effect model and expressed in terms of pooled prevalence rates.

RESULTS

A total of 6522 AIP patients and sixty-two studies were included in the analysis. The pooled estimate rate for the overall prevalence of diabetes in AIP at baseline was 37% (95% CI 32-42, I² 96%). The pooled prevalence rate of exocrine insufficiency was 45% (95%CI 32.9-57.4; I² 97%). The pooled estimate rate of diabetes at follow-up was 44% (95%CI 26.1-62.4) in studies where GCs were given to 100% of patients and 42% (95%CI 30.6-52.9) in studies where GCs were given to less than 100% of patients.

CONCLUSION

A large proportion of patients with AIP displays concomitant exocrine and endocrine insufficiency at the time of diagnosis. The incidence of diabetes at the longest available follow up tends to increase in patients treated with GCs.

IgG4-related disease. Clinical manifestation differential diagnosis and recent International Diagnostic Criteria for IgG4-related disease

Immunoglobulin G4- related disease (IgG4-RD) is a rare systemic fibro-inflammatory disorder. Autoimmune pancreatitis is the most frequent manifestation of IgG4-RD. However, IgG4-RD can affect any organ such as salivary glands, orbits, retroperitoneum, prostate and many others. Recent research enabled a clear clinical and histopathological description of IgG4-RD and in 2019 four Clinical phenotypes of IgG4-related disease were described. Diagnosis is based on morphological examination with typical findings of lymphoplasmocellular inflammation, storiform fibrosis and obliterative phlebitis in IgG4-RD biopsies and the tissue invading plasma cells largely produce IgG4. Elevated serum IgG4 levels are found in many but not all patients. New diagnostic criteria for IgG4-RD have been published recently in 2019 and 2021. This review summarizes current knowledge on pathophysiology, clinical manifestations, diagnosis and differential diagnosis of IgG4-RD from the point of view 2022 and in next article brings overview of the IgG4-RD therapy.

Dupilumab as an adjunct treatment for a patient with steroid-dependent immunoglobulin G4-related disease complicated by asthma: a case report

Introduction: Immunoglobulin G4-related disease (IgG4-RD) responds well to glucocorticoids but is often associated with relapses. Interleukin (IL)-4 and IL-13 are involved in the pathogenesis of IgG4-RD. We present the first case in which dupilumab was an effective adjunct treatment for a patient with steroid-dependent IgG4-RD complicated by asthma.Case study: A 57-year-old man was referred to our hospital for further investigation and treatment of proptosis with neck swelling in 2019. He developed a cough and swelling of the neck in 2016. He was diagnosed with asthma in 2017 and started receiving inhaled glucocorticoids and a long-acting beta-agonist. The patient started receiving oral prednisolone at a dose of 20 mg/day. Oral prednisolone reduced his symptoms, but he relapsed when treatment was tapered to less than 10 mg/day. He was diagnosed with IgG4-RD through a parotid gland biopsy.Results: Azathioprine was given to reduce systemic glucocorticoids. The prednisolone dose was gradually tapered to 10 mg/day, resulting in the relapse of proptosis and an asthma attack. We added dupilumab, and his asthma symptoms and proptosis improved. Serum IgG4 levels continued to decrease, and the prednisolone dose was tapered to 2 mg.Conclusion: Dupilumab might be useful as an adjunctive treatment for patients with steroid-dependent IgG4-RD complicated by asthma. Serum IgG4 levels can be used as a marker to monitor dupilumab treatment in IgG4-RD.

Determination of the duration of glucocorticoid therapy in type 1 autoimmune pancreatitis: A systematic review and meta-analysis

BACKGROUND

The indications for maintenance glucocorticoid therapy (MGT) and its duration after initial remission of type 1 autoimmune pancreatitis (AIP) remain controversial. In contrast to the Japanese treatment protocol, the Mayo protocol does not recommend MGT after initial remission. This study aimed to evaluate the relapse rate in patients with type 1 AIP according to the duration of glucocorticoid therapy.

METHODS

We conducted a systematic literature review up until November 30, 2020, and identified 40 studies reporting AIP relapse rates. The pooled relapse rates were compared between groups according to the protocol and duration of glucocorticoids (routine vs. no MGT; glucocorticoids ≤6 months vs. 6-12 months vs. 12-36 months vs. ≥ 36 months). The pooled rates of adverse events related to glucocorticoids were also evaluated.

RESULTS

Meta-analysis indicated calculated pooled relapse rates of 46.6% (95% confidence interval (CI), 38.9-54.3%) with glucocorticoids for ≤ 6 months, 44.3% (95% CI, 38.8-49.8%) for 6-12 months, 34.1% (95% CI, 28.6-39.7%) for 12-36 months, and 27.0% (95% CI, 23.4-30.6%) for ≥ 36 months. The rate of relapse was also significantly lower in patients with routine-use protocol of MGT (31.2%; 95% CI, 27.5-34.8%) than in patients with no MGT protocol (44.1%; 95% CI, 35.8-52.4%). Adverse events were comparable between groups.

CONCLUSIONS

The rate of relapse tended to decrease with extended durations of glucocorticoid therapy up to 36 months. Clinicians may decide the duration of glucocorticoids according to patient condition, including comorbidities and risk of relapse.

Long-term clinical course and outcomes of immunoglobulin G4-related lung disease

Background

Immunoglobulin G4-related lung disease (IgG4-RLD) is the pulmonary manifestation of a systemic fibroinflammatory disease characterized by lymphoplasmacytic infiltration with an abundance of IgG4-positive plasma cells. Long-term clinical course and outcomes of IgG4-RLD remain unclear. We aimed to identify clinical characteristics, treatment outcomes, and longitudinal pulmonary function changes in patients with IgG4-RLD according to the radiologic classification.

Methods

Chest computed tomography findings of 37 subjects were classified into five subtypes: solid nodular, bronchovascular, alveolar interstitial, round ground glass opacity, and alveolar consolidative. Radiologic treatment outcomes and longitudinal pulmonary function changes were compared among the different radiologic subtypes.

Results

The mean age of the subjects was 55.6 years, and 78.4% were male. Among the five radiologic subtypes, alveolar consolidative and solid nodular type were most common, accounting for approximately 29.7% each of the total cases. Prednisone with or without azathioprine was administered to 31 patients (median treatment duration 14 months). In the treated patients, serial images showed complete response or partial response in 77.4%. However, relapse was documented in 25.0% of those who showed complete or partial response. In patients whose longitudinal lung function data were available (n = 20), the lung function was found to be stable during follow-up. Alveolar consolidative type showed the highest complete response rate, whereas alveolar interstitial type showed the lowest response rate, either complete or partial.

Conclusions

Most patients showed a favorable outcome with regards to radiologic improvement and maintenance of pulmonary function; however, the response differed according to the radiologic subtype.

Autoimmune pancreatitis masquerading as carcinoma head of pancreas: A case report and review of literature

Introduction

Autoimmune pancreatitis (AIP) is a rare form of chronic inflammatory pancreatic disease secondary to an underlying autoimmune mechanism. It is now considered as pancreatic manifestation of IgG4 related disease, which is a multisystem disease.

Case report

We are reporting a patient who presented with obstructive jaundice and mass head of pancreas on Computed Tomography (CT) scan. Considering a strong clinical suspicion of pancreatic cancer, Whipple procedure was done. Histopathological report revealed intense lymphoplasmacytic infiltrate and fibrosis with collagenisation, so possibility of AIP was suggested. Serum IgG4 levels were advised and found to be increased. Diagnosis of AIP was made and patient responded to steroids.

Discussion

Pre-operative core biopsy of the pancreas and Serum IgG4 levels are sufficient to make the diagnosis and resection is usually not recommended in AIP.

Conclusion

Awareness of the entity and use of ancillary techniques in making the pre-operative diagnosis could have saved the patient from an extensive surgical procedure.

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Autoimmune Pancreatitis is a pancreatic manifestation of IgG4 related disorders.

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It can clinically and radiologically present as pancreatic malignancy.

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Resection is not required in Autoimmune Pancreatitis.

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Pre-operative investigations can save the patient from morbidity due to Whipples.

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Whipples procedure is undesired in these patients.

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This entity should be kept in mind while dealing with mass lesions in head of pancreas.

Risk Factors for Rate of Relapse and Effects of Steroid Maintenance Therapy in Patients With Autoimmune Pancreatitis: Systematic Review and Meta-analysis

BACKGROUND & AIMS

Risk for relapse after induction of remission with steroid therapy has been studied extensively in patients with autoimmune pancreatitis (AIP), but findings have been equivocal. We performed a systematic review and meta-analysis to estimate the relapse rate of AIP after initial remission after steroid treatment and to identify factors associated with relapse.

METHODS

Three reviewers searched MEDLINE, SCOPUS, and EMBASE until July 2018 to identify studies on rate of relapse of AIP after induction of remission with steroid therapy. A pooled estimate was calculated using the DerSimonian and Laird method for a random-effects model. This study was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Thirty-six studies met the inclusion criteria for meta-analysis. The median follow-up time was 40.8 months. Fifty-two percent of patients were classified as having type 1 AIP. The pooled estimate of relapse rate was 33% (95% CI, 30%-37%). A higher proportion of patients with type 1 AIP had a relapse compared with patients with type 2 AIP (37.5% vs 15.9%; P < .001). We found significant heterogeneity among studies (P < .01). Long-term maintenance therapy with steroids and study quality were associated independently with AIP relapse, after we adjusted for year of publication by multivariate meta-regression.

CONCLUSIONS

In a systematic review and meta-analysis, we found that a large proportion of patients with AIP treated successfully with steroid induction therapy had a relapse (33%)-particularly patients with type 1 AIP (37%). Maintenance steroid therapy lasting longer than 1 year could reduce risk of relapse. However, the data characterizing relapse rates are of limited quality, indicating the need for randomized controlled trials and new immunosuppressive drugs.

Autoimmune Pancreatitis

Over the course of the last 2 decades our knowledge of autoimmune pancreatitis has increased exponentially. In this review, we summarize the clinical presentation, diagnosis and treatment of AIP, to better allow general gastroenterologists and primary care providers to consider AIP as a as a rare but important cause of painless obstructive jaundice and recurrent acute pancreatitis. While steroids remain the mainstay of first line therapy, a number of patients with type 1 AIP require immunomodulators or rituximab to maintain remission; recommendations on the management of relapses continue to evolve.

Clinical and pathophysiological aspects of type 1 autoimmune pancreatitis

In 1995, Yoshida and colleagues proposed the concept of "autoimmune pancreatitis" (AIP), which has recently been recognized as a new pancreatic inflammatory disease. Recent studies have suggested the existence of two subtypes of AIP: type 1, which involves immunoglobulin G4 (IgG4) and is the pancreatic manifestation of IgG4-related disease (IgG4-RD); and type 2, which is characterized by granulocytic epithelial lesions. Type 2 AIP is thought to be rare in Japan. Type 1 AIP is characterized by increased serum IgG4 concentrations, lymphoplasmacytic infiltrations, storiform fibrosis, and obliterative phlebitis. However, although type 1 AIP has become increasingly recognized, many clinical and basic issues remain to be solved. This review provides an overview of the recent clinical and basic knowledge of type 1 AIP.

Diagnosis and Management of Autoimmune Pancreatitis

OPINION STATEMENT

Although autoimmune pancreatitis is a relatively uncommon pancreatic disorder, it is an important consideration in the differential diagnosis of jaundice and pancreatic masses to avoid unnecessary surgical resection. The clinical diagnosis of autoimmune pancreatitis involves considering multiple pieces of information including the pancreatic imaging, serum IgG4 level, presence of characteristic other involvement, and histologic findings. Unlike other pancreatic disorders, this condition rapidly responds to treatment with steroids. In the more common disease subtype (type 1 autoimmune pancreatitis) disease relapses can occur necessitating the use of maintenance treatment with low-dose steroids, steroid-sparing immunomodulators, or rituximab. This chapter reviews the diagnosis and treatment of the autoimmune pancreatitis subtypes.

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

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

IgG4-related retroperitoneal fibrosis: a newly characterized disease

Retroperitoneal fibrosis (RPF) is a rare disease characterized by chronic, nonspecific inflammatory and sclerotic or fibrotic tissue in the periaortic or periiliac retroperitoneum that encases adjacent structures. There will be a series of clinical manifestations once the proliferated fibrous tissues encase the abdominal aorta, iliac arteries and urinary duct. RPF is generally divided into two types: idiopathic retroperitoneal fibrosis (IRPF) without identified pathogenesis, making up about two-thirds of cases, and secondary retroperitoneal fibrosis. Recent studies on Immunoglobulin G4-related disease (IgG4-RD) reveal that abundant infiltration of IgG4 positive plasma cells is found in biopsies on the mass of RPF of some IRPF patients, which is identified as one spectrum of IgG4-RD and is named IgG4-related RPF. IgG4-related RPF is often misdiagnosed as retroperitoneal visceral malignancy and is treated with surgery. In addition, because of its good response to glucocorticoid, early detection and treatment is important. We review the definition, epidemiology, clinical features, diagnostic criteria, treatment and prognosis of IgG4-related RPF in this article to raise awareness of this newly characterized disease.

Obstructive jaundice in autoimmune pancreatitis can be safely treated with corticosteroids alone without biliary stenting

OBJECTIVE

Autoimmune pancreatitis (AIP) responds dramatically to corticosteroids treatment. We reviewed our experience to determine the safety and effectiveness of treating obstructive jaundice in definitive AIP with corticosteroids alone without biliary stenting.

METHODS

From our AIP database, we retrospectively identified type 1 AIP subjects whose jaundice was treated with corticosteroids alone without biliary stenting. Their medical records were reviewed and clinical data were evaluated to determine the outcomes.

RESULTS

Fifteen AIP subjects (87% male, mean age 68.4 years) were treated with corticosteroids at initial presentation (n = 8), first (n = 5) or subsequent (n = 2) relapse. Mean values (upper limit of normal, ULN) of liver tests prior to corticosteroids were aspartate aminotransferase (AST) 203.5u/l (4 × ULN), alanine aminotransferase (ALT) 325.8u/l (6 × ULN), alkaline phosphatase (ALP) 567.4u/l (5 × ULN), and total bilirubin (TB) 5.9 mg/dl (5.9 × ULN). At first follow-up (mean 4 days) the decrease was 54.9% for AST, 51.6% for ALT, 33% for ALP and 47.2% for TB (all p < 0.05). After 15-45 days, all patients had normal AST, 3/15 had ALT > 1.5 × ULN, 1/15 had ALP > 1.5 × ULN, 1/15 had TB > 1.5 × ULN. No patient required biliary stent placement, or developed cholangitis or other infectious complications during steroid treatment.

CONCLUSION

Under the supervision of an experienced pancreatologist and with close monitoring of patients, obstructive jaundice secondary to definitive AIP can be safely and effectively managed with corticosteroids alone, without the need for biliary stenting.

Diagnosis, treatment and long-term outcomes of autoimmune pancreatitis in Spain based on the International Consensus Diagnostic Criteria: A multi-centre study

OBJECTIVES

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that has been reported worldwide for the last two decades. The aim of this study is to analyse the clinical profile of patients from Spain with AIP, as well as treatments, relapses and long-term outcomes.

METHODS

Data from 59 patients with suspected AIP that had been diagnosed in 15 institutions are retrospectively analysed. Subjects are classified according to the International Consensus Diagnostic Criteria (ICDC). Patients with type 1 AIP (AIP1) and type 2 AIP (AIP2) are compared. Kaplan-Meier methodology is used to estimate the overall survival without relapses.

RESULTS

Fifty-two patients met ICDC, 45 patients were AIP1 (86.5%). Common manifestations included abdominal pain (65.4%) and obstructive jaundice (51.9%). Diffuse enlargement of pancreas was present in 51.0%; other organ involvement was present in 61.5%. Serum IgG4 increased in 76.7% of AIP1 patients vs. 20.0% in AIP2 (p = 0.028). Tissue specimens were obtained in 76.9%. Initial successful treatment with steroids or surgery was achieved in 79.8% and 17.3%, respectively. Maintenance treatment was given in 59.6%. Relapses were present in 40.4% of AIP1, with a median of 483 days. Successful long-term remission was achieved in 86.4%.

CONCLUSIONS

AIP1 is the most frequent form of AIP in Spain in our dataset. Regularly, ICDC allows AIP diagnosis without the need for surgery. Steroid and chirurgic treatments were effective and safe in most patients with AIP, although maintenance was required many times because of their tendency to relapse. Long-term serious consequences were uncommon.

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

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

IgG4-Seronegative Autoimmune Pancreatitis and Sclerosing Cholangitis

IgG4-related disease is a relatively novel clinical entity whose gastrointestinal manifestations include type 1 autoimmune pancreatitis (AIP) and IgG4-associated sclerosing cholangitis. The presence of elevated serum IgG4 is suggestive but not essential for the diagnosis of type 1 AIP and is a pervasive feature of the proposed diagnostic criteria. The differential diagnosis of type 1 AIP includes malignant conditions, emphasizing the importance of a deliberate, comprehensive evaluation. Management of patients with a suggestive clinical presentation, but without serum IgG4 elevation, is difficult. Here we present three cases of IgG4-seronegative AIP and sclerosing cholangitis that responded to empiric steroid therapy and discuss approach considerations. These cases demonstrate the value of meticulous application of existing diagnostic algorithms to achieve a clinical diagnosis and avoid surgical intervention.

Recent Advances in Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that is characterized clinically by frequent presentation with obstructive jaundice, histologically by a dense lymphoplasmacytic infiltrate with fibrosis, and therapeutically by a dramatic response to corticosteroid therapy. Two distinct diseases, type 1 and type 2 AIP, share these features. However, these 2 diseases have unique pancreatic histopathologic patterns and differ significantly in their demographic profiles, clinical presentation, and natural history. Recognizing the popular and long-standing association of the term "AIP" with what is now called "type 1 AIP," we suggest using "AIP" solely for type 1 AIP and to acknowledge its own distinct disease status by using "idiopathic duct-centric chronic pancreatitis" (IDCP) for type 2 AIP. AIP is the pancreatic manifestation of immunoglobulin G4-related disease (IgG4-RD). The etiopathogenesis of AIP and IgG4-RD is largely unknown. However, the remarkable effectiveness of B-cell depletion therapy with rituximab in patients with AIP and IgG4-RD highlights the crucial role of B cells in its pathogenesis. IDCP is less commonly recognized, and little is known about its pathogenesis. IDCP has no biomarker but is associated with inflammatory bowel disease in ~25% of patients. Recently, the international consensus diagnostic criteria for AIP identified combinations of features that are diagnostic of both diseases. Both AIP and IDCP are corticosteroid responsive; however, relapses are common in AIP and rare in IDCP. Therefore, maintenance therapy with either an immunomodulator (eg, azathioprine, 6-mercaptopurine, or mycophenolate mofetil) or rituximab is often necessary for patients with AIP. Long-term survival is excellent for both patients with AIP and patients with IDCP.

A mass in the junction of the body and tail of the pancreas with negative IgG4 serology: IgG4-related disease with negative serology

Patient:Female, 55

Final Diagnosis: Autoimmune pancreatitis

Symptoms: Abdominal pain • weight loss

Medication: Prednisone

Clinical Procedure: Admitted to the hospital

Specialty: Gastroenterology and Hepatology

Lymphoplasmacytic sclerosing pancreatitis without IgG4 tissue infiltration or serum IgG4 elevation: IgG4-related disease without IgG4

Type 1 autoimmune pancreatitis can be diagnosed by and is synonymous with its pathognomonic histopathologic appearance called lymphoplasmacytic sclerosing pancreatitis. Type 1 autoimmune pancreatitis, also called IgG4-related pancreatitis, is the pancreatic manifestation of IgG4-related disease. However, the role of IgG4 in the pathogenesis of IgG4-related disease is unclear. We describe patients with LPSP without serum or tissue IgG4 abnormalities. From the Mayo Clinic database of autoimmune pancreatitis patients, we identified three patients with histologically confirmed type 1 autoimmune pancreatitis (lymphoplasmacytic sclerosing pancreatitis) who had normal serum IgG4 and no increase in IgG4-positive plasma cells in tissue. We reviewed original clinical records and pathologic specimens, and describe the clinical and histologic features of these three patients. All patients (age/gender: 63/F, 70/M and 68/M) had normal serum IgG and IgG4 levels, and multiple sections of pancreatic histology did not show increased IgG4-positive plasma cells. Two patients were diagnosed retrospectively following pancreatic surgery, one relapsed in another organ and one has remained relapse free. Another patient was diagnosed by pancreatic core biopsy and has suffered multiple relapses that have been controlled by rituximab. These cases highlight the fact that although the currently agreed upon name for type 1 autoimmune pancreatitis is IgG4-related pancreatitis, serum and tissue IgG4 abnormalities are best considered characteristic, but not essential for the diagnosis of this enigmatic condition.

Diagnosis and treatment of autoimmune pancreatitis: experience with 100 patients

BACKGROUND

Autoimmune pancreatitis (AIP) is increasingly recognized as a unique subtype of pancreatitis. This study aimed to analyze the diagnosis and treatment of AIP patients from a tertiary care center in China.

METHODS

One hundred patients with AIP who had been treated from January 2005 to December 2012 in our hospital were enrolled in this study. We retrospectively reviewed the data of clinical manifestations, laboratory tests, imaging examinations, pathological examinations, treatment and outcomes of the patients.

RESULTS

The median age of the patients at onset was 57 years (range 23-82) with a male to female ratio of 8.1:1. The common manifestations of the patients included obstructive jaundice (49 patients, 49.0%), abdominal pain (30, 30.0%), and acute pancreatitis (11, 11.0%). Biliary involvement was one of the most extrapancreatic manifestations (64, 64.0%). Fifty-six (56.0%) and 43 (43.0%) patients were classified into focal-type and diffuse-type respectively according to the imaging examinations. The levels of serum IgG and IgG4 were elevated in 69.4% (43/62) and 92.0% (69/75) patients. Pathological analysis of specimens from 27 patients supported the diagnosis of lymphoplasmacytic sclerosing pancreatitis, and marked (>10 cells/HPF) IgG4 positive cells were found in 20 (74.1%) patients. Steroid treatment and surgery as the main initial treatments were given to 41 (41.0%) and 28 (28.0%) patients, respectively. The remission rate after the initial treatment was 85.0%. Steroid was given as the treatment after relapse in most of the patients and the total remission rate at the end of follow-up was 96.0%.

CONCLUSIONS

Clinical manifestations, laboratory tests, imaging and pathology examinations in combination could increase the diagnostic accuracy of AIP. Steroid treatment with an initial dose of 30 or 40 mg prednisone is effective and safe in most patients with AIP.

Diagnosis of autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a distinct form of chronic pancreatitis that is increasingly being reported. The presentation and clinical image findings of AIP sometimes resemble those of several pancreatic malignancies, but the therapeutic strategy differs appreciably. Therefore, accurate diagnosis is necessary for cases of AIP. To date, AIP is classified into two distinct subtypes from the viewpoints of etiology, serum markers, histology, other organ involvements, and frequency of relapse: type 1 is related to IgG4 (lymphoplasmacytic sclerosing pancreatitis) and type 2 is related to a granulocytic epithelial lesion (idiopathic duct-centric chronic pancreatitis). Both types of AIP are characterized by focal or diffuse pancreatic enlargement accompanied with a narrowing of the main pancreatic duct, and both show dramatic responses to corticosteroid. Unlike type 2, type 1 is characteristically associated with increasing levels of serum IgG4 and positive serum autoantibodies, abundant infiltration of IgG4-positive plasmacytes, frequent extrapancreatic lesions, and relapse. These findings have led several countries to propose diagnostic criteria for AIP, which consist of essentially similar diagnostic items; however, several differences exist for each country, mainly due to differences in the definition of AIP and the modalities used to diagnose this disease. An attempt to unite the diagnostic criteria worldwide was made with the publication in 2011 of the international consensus diagnostic criteria for AIP, established at the 2010 Congress of the International Association of Pancreatology (IAP).

IgG4- related disease: an orphan disease with many faces

Immunoglobulin G4- related disease (IgG4-RD) is a rare systemic fibro-inflammatory disorder (ORPHA284264). Although patients have been described more than 100 years ago, the systemic nature of this disease has been recognized in the 21^st century only. Type 1 autoimmune pancreatitis is the most frequent manifestation of IgG4-RD. However, IgG4-RD can affect any organ such as salivary glands, orbits, retroperitoneum and many others. Recent research enabled a clear clinical and histopathological description of IgG4-RD. Typically, lymphoplasmacellular inflammation, storiform fibrosis and obliterative phlebitis are found in IgG4-RD biopsies and the tissue invading plasma cells largely produce IgG4. Elevated serum IgG4 levels are found in many but not all patients. Consequently, diagnostic criteria for IgG4-RD have been proposed recently. Treatment is largely based on clinical experience and retrospective case series. Glucocorticoids are the mainstay of therapy, although adjunctive immunosuppressive agents are used in relapsing patients. This review summarizes current knowledge on clinical manifestations, pathophysiology and treatment of IgG4-RD.

Amendment of the Japanese Consensus Guidelines for Autoimmune Pancreatitis, 2013 III. Treatment and prognosis of autoimmune pancreatitis

The standard treatment for autoimmune pancreatitis (AIP) is steroid therapy, although some patients improve spontaneously. Indications for steroid therapy in AIP patients are symptoms such as obstructive jaundice, abdominal pain, back pain, and the presence of symptomatic extrapancreatic lesions. Prior to steroid therapy, obstructive jaundice should be managed by biliary drainage, and blood glucose levels should be controlled in patients with diabetes mellitus. The recommended initial oral prednisolone dose for induction of remission is 0.6 mg/kg/day, which is administered for 2-4 weeks. The dose is then tapered by 5 mg every 1-2 weeks, based on changes in 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. Cessation of steroid therapy should be based on the disease activity in each case. Termination of maintenance therapy should be planned within 3 years in cases with radiological and serological improvement. Re-administration or dose-up of steroid is effective for treating AIP relapse. Application of immunomodulatory drugs is considered for AIP patients who prove resistant to steroid therapy. The prognosis of AIP appears to be good over the short-term with steroid therapy. The long-term outcome is less clear, as there are many unknown factors, such as relapse, pancreatic exocrine or endocrine dysfunction, and associated malignancy.

Long-term outcomes of autoimmune pancreatitis: a multicentre, international analysis

OBJECTIVE

Autoimmune pancreatitis (AIP) is a treatable form of chronic pancreatitis that has been increasingly recognised over the last decade. We set out to better understand the current burden of AIP at several academic institutions diagnosed using the International Consensus Diagnostic Criteria, and to describe long-term outcomes, including organs involved, treatments, relapse frequency and long-term sequelae.

DESIGN

23 institutions from 10 different countries participated in this multinational analysis. A total of 1064 patients meeting the International Consensus Diagnostic Criteria for type 1 (n=978) or type 2 (n=86) AIP were included. Data regarding treatments, relapses and sequelae were obtained.

RESULTS

The majority of patients with type 1 (99%) and type 2 (92%) AIP who were treated with steroids went into clinical remission. Most patients with jaundice required biliary stent placement (71% of type 1 and 77% of type 2 AIP). Relapses were more common in patients with type 1 (31%) versus type 2 AIP (9%, p<0.001), especially those with IgG4-related sclerosing cholangitis (56% vs 26%, p<0.001). Relapses typically occurred in the pancreas or biliary tree. Retreatment with steroids remained effective at inducing remission with or without alternative treatment, such as azathioprine. Pancreatic duct stones and cancer were uncommon sequelae in type 1 AIP and did not occur in type 2 AIP during the study period.

CONCLUSIONS

AIP is a global disease which uniformly displays a high response to steroid treatment and tendency to relapse in the pancreas and biliary tree. Potential long-term sequelae include pancreatic duct stones and malignancy, however they were uncommon during the study period and require additional follow-up. Additional studies investigating prevention and treatment of disease relapses are needed.

Treatment of relapsing autoimmune pancreatitis with immunomodulators and rituximab: the Mayo Clinic experience

BACKGROUND

There is a paucity of data on long-term management of type 1 autoimmune pancreatitis (AIP), a relapsing steroid-responsive disorder.

OBJECTIVE

We describe our experience with treatment of relapses and maintenance of remission using steroid-sparing immunomodulators (IMs) and induction of remission using rituximab (RTX).

METHODS

We obtained details of disease relapse and treatment in 116 type 1 AIP patients from clinic visits, medical records and telephone interviews. We compared relapse free survival in those treated with IMs versus those treated with steroids alone, assessed patients' response to RTX, and identified treatment-related complications.

RESULTS

During a median follow-up of 47 months, 52/116 AIP patients experienced 76 relapse episodes. The first relapse was treated with another course of steroids in 24 patients, and with steroids plus IM in another 27 patients; subsequent relapse-free survival until a second relapse was similar in the two groups (p=0.23). 38 patients received an IM for >2 months; failure or intolerance of IM therapy occurred in 17 (45%). 12 patients with steroid or IM intolerance/resistance were treated with RTX, an antiCD20 antibody; 10 (83%) experienced complete remission and had no relapses while on maintenance therapy. Treatment-limiting side effects related to RTX were uncommon.

CONCLUSIONS

In type 1 AIP relapses are common. Relapse-free survival is similar in those treated with steroids plus IM compared to those treated with steroids alone. Nearly half the patients on IMs will relapse during treatment. RTX is effective in the treatment of both IM resistant and steroid intolerant patients.

Recent advances in the diagnosis and management of autoimmune pancreatitis: similarities and differences in Japan and Korea

Two subtypes (types 1 and 2) of autoimmune pancreatitis (AIP) are currently recognized. Type 1 AIP is related to immunoglobulin G4 (lymphoplasmacytic sclerosing pancreatitis), and type 2 AIP is characterized by neutrophilic infiltration into the epithelium of the pancreatic duct (idiopathic duct-centric pancreatitis). Although type 2 AIP is sometimes observed in the United States and Europe, most cases of AIP in Japan and Korea are type 1. The international consensus diagnostic criteria for AIP were created to be applicable worldwide and to distinguish between the two types of AIP. AIP is diagnosed based on the presence of at least one of the five cardinal features (i.e., imaging, serology, other organ involvement, histology, and response to steroid therapy). Oral steroids are the standard therapy for AIP, but immunomodulatory drugs or rituximab have been successfully used for patients with relapsed AIP in the United States and Europe. Generally, the clinical manifestations and demography of AIP are similar between Japan and Korea. However, there are differences in some aspects of the disease, including the proportion of other organ involvement, the prevalence of type 2 AIP, diagnostic criteria and maintenance therapy between the two countries.

Clinical and pathological differences between serum immunoglobulin G4-positive and -negative type 1 autoimmune pancreatitis

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

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

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

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

Retroperitoneal fibrosis associated with immunoglobulin G4-related disease

Retroperitoneal fibrosis is a rare disease characterized by the development of inflammation and fibrosis in the soft tissues of the retroperitoneum and other abdominal organs. Retroperitoneal fibrosis can be of 2 types: idiopathic and secondary. The recently advocated concept and diagnostic criteria of immunoglobulin G4 (IgG4)-related disease, derived from research on autoimmune pancreatitis (AIP), has led to widespread recognition of retroperitoneal fibrosis as a condition caused by IgG4-related disease. We now know that previously diagnosed idiopathic retroperitoneal fibrosis includes IgG4-related disease; however, the actual prevalence is unclear. Conversely, some reports on AIP suggest that retroperitoneal fibrosis is concurrently found in about 10% of IgG4-related disease. Because retroperitoneal fibrosis has no specific symptoms, diagnosis is primarily based on diagnostic imaging (computed tomography and magnetic resonance imaging), which is also useful in evaluating the effect of therapy. Idiopathic retroperitoneal fibrosis can occur at different times with other lesions of IgG4-related disease including AIP. Thus, the IgG4 assay is recommended to diagnose idiopathic retroperitoneal fibrosis. High serum IgG4 levels should be treated and monitored as a symptom of IgG4-related disease. The first line of treatment for retroperitoneal fibrosis is steroid therapy regardless of its cause. For patients with concurrent AIP, i.e., IgG4-related retroperitoneal fibrosis, the starting dose of steroid is usually 30-40 mg/d. The response to steroid therapy is generally favorable. In most cases, the pancreatic lesion and retroperitoneal fibrosis improve after the initial treatment. However, the epidemiology, treatment for recurring retroperitoneal fibrosis, and long-term prognosis are still largely unknown. Further analysis of such cases and research are necessary.

Autoimmune pancreatitis mimicking pancreatic cancer

Context:

Autoimmune pancreatitis is a particular type of pancreatitis of presumed autoimmune etiology, it is an entity distinct from all others forms of chronic pancreatitis, characterized by clinical, histopathological, radiographic, serologic and therapeutic features. This benign disease resembles pancreatic carcinoma both clinically and radiographically.

Case Report:

A 27-year-old man presented with obstructive jaundice and evocative image of pancreatic tumor. A pancreaticoduodenectomy (Whipple operation) was performed and pathological examination of the specimen diagnosed AIP. Patient responded well to a course of corticosteroids with resolution of clinical and biological disorders.

Conclusion:

Accurate and timely diagnosis of autoimmune pancreatitis is particularly important because steroid therapy is effective and pancreatic resection is not necessary.

Autoantibodies in autoimmune pancreatitis

Autoimmune pancreatitis (AIP) was first used to describe cases of pancreatitis with narrowing of the pancreatic duct, enlargement of the pancreas, hyper-γ-globulinaemia, and antinuclear antibody (ANA) positivity serologically. The main differential diagnosis, is pancreatic cancer, which can be ruled out through radiological, serological, and histological investigations. The targets of ANA in patients with autoimmune pancreatitis do not appear to be similar to those found in other rheumatological diseases, as dsDNA, SS-A, and SS-B are not frequently recognized by AIP-related ANA. Other disease-specific autoantibodies, such as, antimitochondrial, antineutrophil cytoplasmic antibodies or diabetes-specific autoantibodies are virtually absent. Further studies have focused on the identification of pancreas-specific autoantigens and reported significant reactivity to lactoferrin, carbonic anhydrase, pancreas secretory trypsin inhibitor, amylase-alpha, heat-shock protein, and plasminogen-binding protein. This paper discusses the findings of these investigations and their relevance to the diagnosis, management, and pathogenesis of autoimmune pancreatitis.

Autoimmune pancreatitis: an update on classification, diagnosis, natural history and management

Autoimmune Pancreatitis (AIP) is a recently recognized chronic fibro-inflammatory disease of the pancreas. Although rare, its recognition continues to increase worldwide. Patients often present with painless obstructive jaundice mimicking pancreatic cancer. Two subtypes of AIP are known-type 1 is a multi-organ disease associated with IgG4; type 2 appears to be a pancreas-specific disorder. Dramatic response to steroid treatment is characteristic of both forms. A non-invasive diagnosis of type 1 AIP may be possible using diagnostic criteria (in ~70% cases) while diagnosis of type 2 requires histology. These subtypes differ in natural history- type 1 often relapses while initial reports suggest that type 2 does not. Long term complications include endocrine and exocrine insufficiency and in case of type 1, disease relapses and complications from extra-pancreatic involvement. Neither form affects long term survival. The treatment and follow-up guidelines continue to evolve with our increasing experience in AIP.

IgG4-related disease: can non-classical histopathological features or the examination of clinically uninvolved tissues be helpful in the diagnosis?

IgG4-related disease (IgG4-RD) is an increasingly recognised inflammatory and fibrosing condition that commonly shows multisystem involvement. The disease may mimic malignancy and other inflammatory or immune-mediated disorders, but usually has a good response to corticosteroid therapy, underlining the requirement for recognition of the condition. Accurate diagnosis requires careful interpretation of varying combinations of serum IgG4 levels, radiological features and characteristic histopathological appearances within an appropriate clinical setting. The presence of 'classical' histopathological features together with an elevated tissue IgG4+ plasma cell count and IgG4 to IgG ratio is often diagnostic and at the very least can strongly support a clinicopathological diagnosis of IgG4-RD. The authors describe the most recent diagnostic criteria for IgG4-RD, especially the histopathological features. The authors then discuss the merits of examining tissues that may be more easily obtainable than those that commonly show the 'classical' histopathological features, but within which not all of these 'diagnostic' features may be present. The authors conclude that while a combination of 'classical' histopathological features and an elevated tissue IgG4+ plasma cell count is the gold standard for diagnosis, examination of tissues that show some but not all of these features can, in the appropriate context, provide useful supporting evidence for a clinicopathological diagnosis of IgG4-RD.

Comparison of clinical findings between histologically confirmed type 1 and type 2 autoimmune pancreatitis

BACKGROUND AND AIM

Type 2 autoimmune pancreatitis (AIP) has been reported mainly in Western countries and is thought to be very rare in Asia. The aim of this study was to compare the prevalence, clinical profiles, detailed radiological findings, and steroid responsiveness between type 1 and type 2 AIP in Korea.

METHODS

From 120 patients diagnosed with AIP between January 2003 and August 2010, 52 patients with histologically confirmed type 1 (n = 37) or type 2 (n = 15) AIP were included.

RESULTS

The median age of patients with type 2 AIP was significantly lower than that of patients with type 1 AIP (61 vs 34 years, P < 0.05). At initial presentation, severe abdominal pain and presentation with acute pancreatitis were more frequent in patients with type 2 AIP (P < 0.05). On computed tomography scan, the extent of pancreatic enlargement and the frequency of low-density mass did not differ significantly between the two groups. Detailed pancreatographic findings on endoscopic retrograde cholangiopancreatography/magnetic resonance cholangiopancreatography were not significantly different between the two groups. All patients with steroids therapy improved clinically and radiologically in response (25/25 in type 1 AIP and 14/14 in type 2 AIP). During the follow-up period, none of the patients with type 2 AIP experienced relapse.

CONCLUSIONS

Type 2 AIP in all histologically confirmed AIP cases in Korea may not be as rare as originally thought, with an estimated prevalence rate of 28.8% (15/52). The detailed radiological findings of type 1 and type 2 AIP were not significantly different, and both subtypes responded well to steroids.

The Clinical and Pathological Features of IgG(4)-Related Disease

The rapidly emerging disorder now known as IgG(4)-related disease (IgG(4)-RD) includes a variety of clinical entities once regarded as being entirely separate diseases. Manifestations of IgG(4)-RD have now been reported in essentially all organ systems. Regardless of which organ is involved, tissue biopsies reveal striking histopathological similarities. The hallmark pathology findings are diffuse lymphoplasmacytic infiltrates, abundant IgG(4)-positive plasma cells, modest tissue eosinophilia, and extensive fibrosis. Tumorous swelling and obliterative phlebitis are other frequently observed features. Polyclonal elevations of serum IgG(4) are found in approximately 70% of patients. Many questions pertaining to the etiology, pathophysiology, epidemiology, clinical features, therapy, disease monitoring, and long-term outcomes remain to be addressed. This paper focuses on the clinical and pathological features of IgG(4)-RD.

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.

[Clinical characteristics of autoimmune pancreatitis]

Korean autoimmune pancreatitis (AIP) criteria 2007 was aimed to diagnose the wide spectrum of AIP with high sensitivity. The most crucial issue when caring for patients with suspected AIP is to differentiate AIP from pancreatic cancer. Pancreatic cancer can be distinguished from AIP by pancreatic imaging, measurement of serum IgG4 levels, endoscopic ultrasound guided fine needle aspiration and trucut biopsy, and steroid trial. Autoimmune pancreatitis is a rare systemic fibroinflammatory disease which can affect not only the pancreas, but also a variety of organs such as the bile ducts, salivary glands, retroperitoneum, and lymph nodes. Organs affected by AIP have a lymphoplasmacytic infiltrate rich in IgG4-positive cells. This inflammatory process responds dramatically to oral steroid therapy. Granulocytic epithelial lesion (GEL) positive AIP patients differ from GEL negative AIP patients in clinical features such as equal gender ratio, younger mean age, no increase in serum IgG4, no association with extrapancreatic involvement, no relapse, and frequent association with inflammatory bowel disease. Further investigation is needed to clarify the pathogenic mechanisms including more definite serological markers for theses two entities.

Idiopathic duct-centric pancreatitis: disease description and endoscopic ultrasonography-guided trucut biopsy diagnosis

BACKGROUND/AIMS

Recent data demonstrate the presence of two autoimmune pancreatitis (AIP) subtypes. All existing endoscopic ultrasonography-guided trucut biopsy (EUS-TCB) data pertain to type 1 disease. Our aim is to determine if EUS-TCB samples are sufficient for diagnosing type 2 AIP.

METHODS

This is a retrospective case series conducted in an academic tertiary care center. Patients included those with type 2 AIP (n = 5), retrospectively identified from a database of all patients with AIP, diagnosed by HISORt criteria (n = 125). The primary outcome measure was the diagnostic capability of EUS-TCB for type 2 AIP.

RESULTS

5 patients (4 male, 1 female; mean age 39.6 years) who underwent EUS-TCB were diagnosed with type 2 AIP. The serum IgG(4) level was elevated in 1 of the 4 patients tested. CT/MRI revealed diffuse pancreas enlargement (n = 3), a pancreas head mass (n = 1), and a normal pancreas (n = 1). Prior to EUS, AIP was not specifically suspected, but part of a broad differential (n = 3) or not suspected at all (n = 2). Fine-needle aspiration was negative for neoplasia and AIP. The TCB histology was definitive (n = 4) or suggestive (n = 1) for type 2 AIP. No complications developed.

CONCLUSIONS

EUS-TCB may be safe and may provide sufficient material to definitively diagnose type 2 AIP. and IAP.

A clinical overview of IgG4-related systemic disease

PURPOSE OF REVIEW

To summarize the existing knowledge of various clinical presentations of IgG4-related systemic disease (IgG4-RSD) and to review the evolving list of organs affected by IgG4-RSD.

RECENT FINDINGS

The term IgG4-RSD encompasses a variety of clinical entities once regarded as being entirely separate diseases. The list of organs associated with this condition is growing steadily. Tissue biopsies reveal striking histopathological similarity, regardless of which organ is involved, although subtle differences across organs exist. Diffuse lymphoplasmacytic infiltrates, presence of abundant IgG4-positive plasma cells and extensive fibrosis are the hallmark pathology findings. Tumorous swelling, eosinophilia, and obliterative phlebitis are other frequently observed features. Polyclonal elevations of serum IgG4 are found in most but not all patients.

SUMMARY

IgG4-RSD is an underrecognized condition about which knowledge is now growing rapidly. Yet there remain many unknowns with regard to its cause, pathogenesis, various clinical presentations, approach to treatment, disease monitoring, and long-term outcomes. A wide variety of organs can be involved in IgG4-RSD. Clinicians should be aware of this entity and consider the diagnosis in the appropriate settings.

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.

Asian chronic pancreatitis: the common and the unique

Chronic pancreatitis (CP) is a disabling condition worldwide that presents as pain, maldigestion, and diabetes. It is usually perceived as alcohol related, or classified as idiopathic otherwise. However, this is true only for Western countries. Asian CP comprises not only alcohol-related CP but also tropical pancreatitis (TP). Tropical pancreatitis is a unique entity commonly found in South Asia. It shares similar presentations with other CPs for pain and maldigestion. However, its diabetes is more ketosis resistant. Non-surgical approach like endoscopic therapy plus extracoporeal shock wave lithotripsy provides better outcome for TP than other CPs, because of its less strictured pancreatic duct that is more amenable to endoscopic stone clearance. Diagnosis of CP in Asia mainly relies on image studies such as ultrasonography ± computed tomography (CT) scan, and non-invasive tests on fecal chymotrypsin, serum trypsin, and serum pancreatic isoamylase. Endoscopic ultrasonography and intestinal tubing tests are used mainly in some research centers. Autoimmune pancreatitis (AIP) is another CP originated from Asia in large series and subsequently being recognized in the West. AIP patients seldom present with maldigestion until the disease progresses to a very late stage and this occurs in less than one third of patients. In contrast, AIP is usually presented as pseudotumor of the pancreatic head, causing obstructive jaundice. Immunoglobulin G4 level is typically elevated in AIP and can be used as a marker for responsiveness. Without a need of surgery, steroids are the standard treatment. Those who relapse and are resistant to steroids should be placed on long-term immunosuppressive agents.

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.

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.

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.