The diagnostic criteria for autoimmune chronic pancreatitis: it is time to make a consensus

What Is the Latest in Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is a steroid-responsive fibroinflammatory disorder with 2 clinically distinct subtypes known as type 1 autoimmune and type 2 autoimmune pancreatitis. Type 1 AIP is considered the pancreatic manifestation of immunoglobulin G4-related disease, a systemic disease often presenting with other organ involvement. Advances in understanding the unique clinical presentation, imaging findings, histopathology, and clinical course of this relatively uncommon disease have led to international consensus regarding diagnosis and treatment. While corticosteroids remain the mainstay of treatment, several emerging novel therapies have been explored primarily in the context or relapsing and refractory cases.

Recent advances in IgG4-related autoimmune pancreatitis

The incidence of IgG4-related autoimmune pancreatitis (IgG4-AIP) is high in Asia and other countries, and unnecessary treatment is often undertaken due to both missed diagnosis and misdiagnosis in clinical practice. Although IgG4-AIP has attracted increasing attention, the details of IgG4-AIP pathogenesis and systemic immune response, including its relationship to tumor pathogenesis, are still unclear. In recent years, research on serum immunological detection, pathological features, clinical manifestations, diagnosis and treatment measures for IgG4-AIP has gradually increased. It is of great importance to summarize and discuss the latest progress regarding IgG4-AIP disease.

Main Diagnostic Criteria Usually Does Not Work for Autoimmune Pancreatitis Wrongly Presuming Malignancy

Background

Autoimmune pancreatitis (AIP) usually responds dramatically to steroid therapy. Occasionally, however, misdiagnosed patients have undergone pancreaticoduodenectomy. This study is aimed at providing useful information to improve the accuracy of diagnosis before surgery and thus avoid unnecessary resections in patients with AIP.

Methods

From January 2015 to February 2020, a series of patients were enrolled, having undergone pancreaticoduodenectomy for presumed malignancy. AIP diagnoses were confirmed by postoperative pathology. The demographic and clinical data of the AIP patients were evaluated. The main diagnostic criteria (HISORt, Asian, and ICDC) for AIP were applied to assess whether and how unnecessary surgery could have been avoided.

Results

A total of 124 cases of pancreaticoduodenectomy were performed for presumed malignancy. Six patients were diagnosed with benign disease and five with AIP. The prevalences of benign disease and AIP were 4.8% and 4%, respectively. Four patients were female and 1 male, with a mean age of 60.0 years old. Jaundice, pain, and weight loss were observed in 100%, 20%, and 40% of AIP patients, respectively. The radiologic features of the AIP patients were a diffusely enlarged gland (40.0%), a focally enlarged gland (40.0%), pancreatic ductal dilatation (60.0%), upstream parenchymal atrophy (20.0%), bile duct thickening (66.0%), and bile duct stricture (40.0%). Based on the diagnostic criteria for AIP, surgery could have been avoided in two cases.

Conclusions

IgG4 measurement and integrated use of major diagnostic criteria should be emphasized in every patient eligible for pancreaticoduodenectomies.

Obstructive Jaundice Mimicking Pancreatic Cancer: An Unusual Presentation of Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is an uncommon variant of chronic pancreatitis characterized by inflammatory changes within the pancreatic tissue triggered by autoimmune mechanisms. It is known to mimic pancreatic cancer due to its similar clinical and radiological presentations. We underline a case of a 55-year-old male who presented with weight loss, jaundice, and pruritus. Radiological imaging suggested a pancreatic mass, raising suspicion of malignancy. However, subsequent evaluation, absence of parenchymal tissue and lymphoplasmacytic cells on endoscopic ultrasound-guided biopsy, and elevated serum immunoglobulin G4 level resulted in the diagnosis of AIP. Our case emphasizes that AIP should be included in the differential diagnosis of obstructive jaundice, especially when clinical and radiological findings are inconclusive for pancreatic cancer.

Diagnostic Utility of Serum IgG4 in Autoimmune Pancreatitis: An Updated Comprehensive Systematic Review and Meta-analysis

OBJECTIVES

Despite many studies suggesting an association between serum immunoglobulin G4 (sIgG4) and autoimmune pancreatitis (AIP), the evidence of utility in differentiation between AIP and pancreatic cancer (PC) remain uncertain.

METHODS

The analysis based on published studies. Data were pooled by means of a random-effects model, and sensitivity, specificity, diagnostic odds ratios (DOR), areas under summary receiver operating characteristic curves were calculated.

RESULTS

In the included thirteen studies, sIgG4 were measured in 594 patients with AIP and 958 patients with PC. The pooled sensitivity, specificity, DOR, and area under the curve were 0.72 [95% confidence interval (CI): 0.68-0.75], 0.93 (95% CI: 0.92-0.95), 51.37 (95% CI: 23.20-113.74), and 0.91 (95% CI: 0.87-0.95). Subgroup analyses of the DORs for region and year: Asia, (112.10; 95% CI: 27.72-453.32), non-Asia (26.01; 95% CI: 12.38-54.65), and year before 2011 (107.61; 95% CI: 39.30-294.68), year after 2011 (26.96; 95% CI: 9.78-74.32). Overall, sIgG4 was associated with AIP, the result revealed a moderate sensitivity 0.72 and high specificity 0.93. In the meta-analysis, the pooled DOR of sIgG4 levels of 2-fold upper limit 50.44 was similar with the DOR 51.37 when 1-fold cut-off value, but the summary receiver operating characteristic was 0.755 and 0.91. The higher specificity (from 93% to 98%) derived from the cut-off value (from 130-140 to 260-280 mg/dL) for sIgG4 occurred at a significant reduction in sensitivity (from 72% to 43%).

CONCLUSIONS

The study revealed sIgG4 is a good marker of AIP. Screening of sIgG4 may help clinicians differentiate between AIP and PC, and the best cut-off value should be 140 rather than 280 mg/dL.

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.

Autoimmune pancreatitis: What we know so far

Autoimmune pancreatitis (AIP) is a rare, often‐missed disease that involves inflammation of the pancreas and strictures of the pancreatic duct. Its prevalence and incidence in the United States remain scarce. The disease has a varied presentation and often mimics pancreatic malignancy, which can make the diagnosis challenging. Most patients have an excellent response to corticosteroid therapy. Immunomodulators may be used in some cases. Rituximab is an effective, emerging treatment in steroid‐refractory cases. This study aims to review the two distinct types of AIP and provide a detailed analysis of the diagnostic approach and treatment modalities.

Focal Autoimmune Pancreatitis: A Simple Flow Chart for a Challenging Diagnosis

Autoimmune pancreatitis is a chronic fibroinflammatory autoimmune mediated disease of the pancreas. Clinically, obstructive painless jaundice and upper abdominal pain are the main symptoms. Focal AIP is characterized by segmental involvement of pancreatic parenchyma and it is often radiologically represented by a pancreatic mass. In these cases, the diagnosis can be very challenging, since it may be easily confused with pancreatic cancer. Therefore, we suggest a combined approach of imaging tests as the diagnostic workup. EUS study combined with CEUS and elastography, if available, increases the accuracy of the method to rule out cancer. Moreover, the lesion should always be sampled under EUS guidance to obtain a cyto/histological diagnosis. The diagnostic workup should also include the use of diagnostic clinical criteria (extrapancreatic lesions, steroid response) and laboratory findings (CA 19.9 and IgG4 evaluations).

Diagnosis and management of IgG4-related disease

IgG subclass 4-related disease (IgG4-RD) is a rare but increasingly recognised fibroinflammatory condition known to affect multiple organs. IgG4-RD is characterised by unique histological features of lymphoplasmacytic infiltration, storiform fibrosis and obliterative phlebitis. In this review we describe the pancreaticobiliary manifestations of IgG4-RD, with particular emphasis on type 1 autoimmune pancreatitis (AIP) and IgG4-related sclerosing cholangitis (IgG4-SC). AIP and IgG4-SC can pose diagnostic challenges to the clinician as they may mimic pancreatic cancer and primary sclerosing cholangitis, respectively. We discuss current knowledge, clinical diagnostic criteria and recent advances and summarise the evidence base for current therapeutic approaches for AIP and IgG4-SC.

Unclassified autoimmune pancreatitis mimicking pancreatic cancer

A 24-year-old black male presented with a 1-week obstructive jaundice and intermittent abdominal pain, with no significant weight loss and an unsuspicious abdominal exam. Blood chemistry showed a cholestatic pattern but a complete immunological and tumoral panel (anti-smooth muscle antibody, anti-mitochondrial antibody, anti-nuclear antibody, anti-neutrophil cytoplasmic antibody, anti-Smith, anti-double-stranded-DNA antibody (anti-dsDNA), complement C3/C4, carcinoembryonic antigen, CA 19-9 and IgG4) were all within normal limits. Abdominal ultrasound revealed dilatation of the intra and extra-hepatic bile ducts. CT scan showed an abnormal dilatation of the distal bile duct but no focal enlargement of the head of the pancreas. Endoscopic ultrasound suggested an inflammatory process but the magnetic resonance cholangio-pancreatography favored a neoplastic obstruction of the distal common bile duct. Fine-needle aspiration cytology was insufficient for definitive diagnosis and the patient underwent major surgery. Follow-up with mild exocrine pancreatic insufficiency treated with enzyme replacement.

Diagnosis, treatment and long-term outcome of autoimmune pancreatitis in Sweden

INTRODUCTION

Autoimmune pancreatitis (AIP) is a pancreatic inflammatory process characterized by a strong inflammatory cell infiltration and two histopathologically distinct subtypes: type 1 and type 2. Diagnosis is often challenging and requires a combination of clinical, laboratory and imaging data. AIP can mimic pancreatic tumours leading to unnecessary resections if not correctly diagnosed. Short- and long-term outcomes of AIP have been poorly investigated so far and no large series have been previously reported from Sweden.

METHODS

A single-centre, retrospective, cohort study of patients with histologically confirmed or highly probable diagnosis of AIP according to ICDC criteria. Demographic, clinical and radiological characteristics, type of treatment and its outcomes were collected and analysed.

RESULTS

Seventy-one patients with AIP (87% with type 1), were evaluated at Karolinska University Hospital between 2004 and 2018; 49% males, mean age 49 years (range 44-53). Among them, 28% were histologically confirmed, 35% presented with jaundice, 22% with acute pancreatitis, 39% had non-specific symptoms such as weight loss or abdominal pain, 84% showed other organ involvement (OOI). Radiologically, 76% showed a focal pancreatic enlargement, 27% diffuse enlargement, 27% signs of acute pancreatitis and 10% of chronic pancreatitis. Overall, 58 patients (81%) underwent treatment with different medications: 46 (79%) cortisone, 7 (12%) azathioprine, 5 (8%) other immunosuppressive drugs. Twenty-six (36%) underwent biliary stenting and 12 (16%) were given surgery. In total, 47% of patients developed pancreatic exocrine insufficiency (PEI), of whom 76% had a severe form (faecal elastase-1 < 100 μg/g) and 21% of patients developed diabetes mellitus (pancreatic endocrine insufficiency), of whom 73% required insulin.

CONCLUSIONS

AIP is a challenging disease for diagnosis and treatment. Cortisone treatment is generally successful and provides clinical remission in the large majority of patients (>90%). In the further course of the disease, a considerable number of patients develop PEI and diabetes. Only one-quarter of patients exhibit on imaging the characteristic "sausage-like" pancreas (diffuse enlargement), approximately three-quarters had a focal mass that could be misdiagnosed as pancreatic malignancy.

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.

The clinical utility of immunoglobulin G4 in the evaluation of autoimmune pancreatitis and pancreatic adenocarcinoma

BACKGROUND

Elevation in the serum immunoglobulin-G4 (IgG4) level has been used as a diagnostic marker to distinguish autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC), but its true utility is ill-defined. This study evaluates the clinical utility of IgG4 in differentiating AIP from PDAC.

METHODS

All patients evaluated in the hepatopancreaticobiliary surgery clinics with measured serum IgG4 were included. Patients were divided into normal IgG4 (<135 mg/dL) and elevated IgG4 (≥135 mg/dL) groups. The final diagnosis was determined by operative pathology when available or by clinical outcome. The sensitivity, specificity, PPV, and NPV of IgG4 for diagnosing AIP was assessed.

RESULTS

Between 1997 and 2015, 298 patients were identified. Normal IgG4 levels were present in 85% of patients (254/298), while 15% (44/298) were elevated. The overall prevalence of AIP was 17% (52/298). The sensitivity and specificity of IgG4 for AIP was 67% and 96%, respectively; however, the PPV was only 80%, including a 9% occurrence of PDAC in patients with an elevated IgG4.

CONCLUSION

In this study of selected patients who underwent IgG4 testing, 9% of elevated IgG4 patients had PDAC. The overreliance on IgG4 as diagnostic for AIP may lead to mis-diagnosis and delayed treatment for PDAC.

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

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

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.

Differentiating Mass-Forming Autoimmune Pancreatitis From Pancreatic Ductal Adenocarcinoma on the Basis of Contrast-Enhanced MRI and DWI Findings

OBJECTIVE

The purpose of this study was to assess value of contrast-enhanced MRI, MRCP, and DWI for differentiating mass-forming autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC).

MATERIALS AND METHODS

This study included 15 patients with mass-forming AIP and 79 with PDAC who underwent gadoxetic acid-enhanced MRI with DWI and MRCP. Two radiologists evaluated the MRI findings in consensus. Statistically significant imaging findings were identified through univariate and multivariate analyses, and their diagnostic performance for predicting mass-forming AIP was analyzed.

RESULTS

In the univariate analysis, multiplicity, similar or high signal intensity on portal phase and 3- and 20-minute delayed phase images, homogeneous enhancement, no peripancreatic fat infiltration, no internal cystic or necrotic portion, capsulelike rim, no upstream pancreatitis, no vascular invasion, and duct penetrating sign were more frequently observed (p < 0.05) in mass-forming AIP. The apparent diffusion coefficient (ADC) value was also significantly lower for mass-forming AIP than for PDAC (0.96 ± 0.14 versus 1.13 ± 0.23 × 10(-3) mm(2)/s; p < 0.001). The optimal cutoff value of ADC for differentiating mass-forming AIP from PDAC was 0.9407 × 10(-3) mm(2)/s. In multivariate analysis, homogeneous enhancement (p = 0.001), duct penetrating sign (p < 0.001), and ADC value less than 0.9407 × 10(-3) mm(2)/s (p < 0.001) were significant for differentiating mass-forming AIP from PDAC. When two of these three criteria were combined, 80% (12/15) of mass-forming AIPs were identified with specificity of 98.7%. When all three criteria were satisfied, specificity was 100%.

CONCLUSION

Contrast-enhanced MRI with MRCP and DWI may be helpful for differentiating mass-forming AIP from PDAC.

A Patient with Autoimmune Pancreatitis Type 1 with Previously Known Lymphadenopathy, Both in the Context of IgG4-related Disease

Patient: Male, 62

Final Diagnosis: Auto-immune pancreatitis

Symptoms: Jaundice • lymfadenopathy

Medication: —

Clinical Procedure: Laboratory • imaging

Specialty: Gastroenterology and Hepatology

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.

CT and MRI Findings of Autoimmune Polymorph Bifocal Pancreatitis Mimicking Pancreatic Adenocarcinoma: A Case Report and Review of the Literature

Autoimmune pancreatitis is a rare type of chronic pancreatitis. It is supposed to be a pancreatic manifestation of an immune-complex modulated systemic disorder. In contrast, pancreatic adenocarcinoma is the most frequent malignant neoplasm of the pancreas. Within the rare type of focal autoimmune pancreatitis, only few presentations with multifocal pancreatic lesions have been described. Herein we report a case of a 58-year-old patient with autoimmune pancreatitis presenting with bifocal manifestations of the pancreatic head and tail, mimicking pancreatic adenocarcinoma clinically, on computed tomography and magnetic resonance imaging. Typical imaging findings of autoimmune pancreatitis are compared with typical findings in pancreatic carcinoma. The diagnostic dilemma of differentiating between both entities is discussed. A review of the present literature regarding multifocal presence of autoimmune pancreatitis is performed.

A non-invasive screening technique for type 1 autoimmune pancreatitis

Introduction

Type 1 autoimmune pancreatitis (AIP) is the pancreatic manifestation of a systemic fibroinflammatory IgG4-related disease. Accurate diagnosis of AIP can avoid major hepatobiliary and pancreatic surgery as it respond dramatically to corticosteroid therapy.

Aim

This research investigated the feasibility of using peripheral blood cell immunohistochemistry, serum IgG4, T-cell receptor (TCR) and serum isoelectric focusing electrophoresis in the screening of type 1 autoimmune pancreatitis (AIP).

Material and methods

The peripheral blood from 3 type 1 AIP patients, 10 pancreatic cancer patients and 40 normal controls was collected. Sediment smears were jointly incubated with anti-IgG4 and anti-IgG. The percentage of IgG4/IgG positive cells was counted and serum TCR and IgG4 were detected through the whole process. After serum isoelectric focusing electrophoresis, anti-IgG4 and anti-IgG were used to confirm the components of serum.

Results

In the serum isoelectric focusing electrophoresis, IgG4 and IgG strips showed mirrored distribution in type 1 AIP patients, while there were no strips in the normal controls and pancreatic cancer. Compared with pancreatic tumor patients and healthy controls, serum TCR was significant increased in AIP. The percentage of IgG4/IgG positive cells of peripheral blood cell immunohistochemistry was related to serum IgG4 and hormone therapy reactions.

Conclusions

Peripheral blood cell immunohistochemistry, serum IgG4, TCR and serum isoelectric focusing electrophoresis is suitable for the screening of type 1 AIP and monitoring its response assessment.

Diagnosis and treatment of autoimmune pancreatitis types 1 and 2

Background

Autoimmune pancreatitis (AIP) is characterized by diffuse or focal swelling of the pancreas. AIP has been divided into types 1 and 2. The aim of the study was to evaluate and compare the clinicopathological characteristics, therapy and outcome of patients with AIP.

Methods

The medical records of patients diagnosed with AIP between January 2003 and July 2011 were reviewed. Characteristics of patients with AIP types 1 and 2 were compared with those of patients with pancreatic ductal adenocarcinoma (PDAC).

Results

AIP was classified as type 1 in 40 patients and type 2 in 32 according to the HISORt (Histology, Imaging, Serology, Other organ involvement, Response to therapy) criteria. Patients with histologically confirmed AIP type 2 were younger than those with type 1 (P = 0·005). Some 30 of 32 patients with AIP type 2 were found to have a localized tumour-like pancreatic mass and underwent pancreatectomy, compared with only 16 of 40 with type 1 (P &lt; 0·001). Three of 25 patients with AIP type 2 presented with raised serum levels of IgG4 compared with 21 of 38 with type 1 (P &lt; 0·001). There was no difference in symptoms and involvement of other organs between AIP types 1 and 2. Presentation with weight loss was more common among patients with PDAC than those with AIP, but there was no difference in pain or jaundice between the groups. Raised serum carbohydrate antigen 19-9 levels were more prevalent in patients with PDAC.

Conclusion

Patients with AIP type 2 frequently present with abdominal pain and a tumour-like mass. Differentiating AIP from PDAC is difficult, so making the clinical decision regarding operative versus conservative management is challenging.

Comparative MRI analysis of morphologic patterns of bile duct disease in IgG4-related systemic disease versus primary sclerosing cholangitis

OBJECTIVE

The purpose of this study was to perform a retrospective MRI-based comparative analysis of the morphologic patterns of bile duct disease in IgG4-related systemic disease (ISD, also called autoimmune pancreatitis) compared with primary sclerosing cholangitis (PSC) and the autoimmune liver diseases autoimmune hepatitis and primary biliary cirrhosis.

MATERIALS AND METHODS

This study included 162 consecutively registered patients (47 with ISD, 73 with PSC, and 42 with autoimmune liver diseases). Two abdominal radiologists retrospectively reviewed MR images in consensus. Imaging findings on the bile ducts, liver, pancreas, and other organs were analyzed to establish disease patterns.

RESULTS

ISD was associated with contiguous thickening of intrahepatic and extrahepatic bile ducts (p<0.001), pancreatic parenchymal abnormalities (p<0.001), renal abnormalities (p<0.001), and gallbladder wall thickening (p<0.03). The severity of common bile duct wall thickness was significantly different in ISD (p<0.001). The mean single wall thickness in the ISD group was 3.00 (SD, 1.47) mm, in the PSC group was 1.89 (SD, 0.73) mm, and in the autoimmune liver disease group was 1.80 (SD, 0.67) mm. PSC was associated with liver parenchymal abnormalities (p<0.001). We did not find statistical significance between the three groups in location (p=0.220) or length (p=0.703) of extrahepatic bile duct strictures, enhancement of bile duct stricture (p=0.033), upper abdominal lymphadenopathy, or retroperitoneal fibrosis. Although presence of intrahepatic bile duct stricture was statistically significant when all three groups were compared, it was not useful for differentiating ISD from PSC.

CONCLUSION

The presence of continuous as opposed to skip disease in the bile ducts, gallbladder involvement, and single-wall common bile duct thickness greater than 2.5 mm supports a diagnosis of ISD over PSC. ISD and PSC could not be differentiated on the basis of location and length of common bile duct stricture.

Autoimmune pancreatitis: multidetector-row computed tomography (MDCT) and magnetic resonance (MR) findings in the Italian experience

Multidetector-row computed tomography (MDCT) and magnetic resonance (MR) imaging are currently the most frequently performed imaging modalities for the study of pancreatic disease. In cases of suspected autoimmune pancreatitis (AIP), a dynamic quadriphasic (precontrast, contrast-enhanced pancreatic, venous and late phases) study is recommended in both techniques. In the diffuse form of autoimmune pancreatitis (DAIP), the pancreatic parenchyma shows diffuse enlargement and appears, during the MDCT and MR contrast-enhanced pancreatic phase, diffusely hypodense and hypointense, respectively, compared to the spleen because of lymphoplasmacytic infiltration and pancreatic fibrosis. During the venous phase of MDCT and MR imaging, the parenchyma appears hyperdense and hyperintense, respectively, in comparison to the pancreatic phase. In the delayed phase of both imaging modalities, it shows retention of contrast media. A "capsule-like rim" may be recognised as a peripancreatic MDCT hyperdense and MR hypointense halo in the T2-weighted images, compared to the parenchyma. DAIP must be differentiated from non-necrotizing acute pancreatitis (NNAP) and lymphoma since both diseases show diffuse enlargement of the pancreatic parenchyma. The differential diagnosis is clinically difficult, and dynamic contrast-enhanced MDCT has an important role. In the focal form of autoimmune pancreatitis (FAIP), the parenchyma shows segmental enlargement involving the head, the body-tail or the tail, with the same contrast pattern as the diffuse form on both modalities. FAIP needs to be differentiated from pancreatic adenocarcinoma to avoid unnecessary surgical procedures, since both diseases have similar clinical and imaging presentation. The differential diagnosis is clinically difficult, and dynamic contrast-enhanced MDCT and MR imaging both have an important role. MR cholangiopancreatography helps in the differential diagnosis. Furthermore, MDCT and MR imaging can identify the extrapancreatic manifestations of AIP, most commonly biliary, renal and retroperitoneal. Finally, in all cases of uncertain diagnosis, MDCT and/or MR follow-up after short-term treatment (2-3 weeks) with high-dose steroids can identify a significant reduction in size of the pancreatic parenchyma and, in FAIP, normalisation of the calibre of the upstream main pancreatic duct.

Diagnosis and classification of autoimmune pancreatitis

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

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

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

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

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

A case of focal autoimmune pancreatitis (AIP) mimicking an intraductal papillary mucinous neoplasm (IPMN)

The present case involved a 76-year-old man with a cystic mass in the head of his pancreas. The cystic lesion, which measured 17.7 × 9.8 mm, was first detected by ultrasonography (US) at the age of 72 years. Follow-up endoscopic ultrasonography (EUS) performed at 4 years after the lesion had first been detected revealed a mural nodule measuring 14.0 × 8.4 mm in the cyst. Endoscopic retrograde pancreatography (ERP) imaging revealed that the main pancreatic duct was in communication with the cyst and that there was no irregular narrowing of the main pancreatic duct. On the basis of these results, the patient was diagnosed with an intraductal papillary mucinous neoplasm (IPMN), and stomach-preserving pancreaticoduodenectomy was performed. A histopathological examination revealed that the interior of the cystic part of the lesion was lined by a pancreatic ductal epithelium. A pathological examination of the nodular lesion detected storiform fibrosis, severe lymphoplasmacytic infiltration, and hyperplasia in the pancreatic duct epithelium together with a small amount of mucus. On immunohistological staining, the infiltrating lymphoplasmacytes were found to be positive for IgG4. Accordingly, the patient was diagnosed with focal autoimmune pancreatitis (AIP). In conclusion, we reported a case of focal AIP mimicking IPMN. This case showed neither enlargement of the pancreas nor irregular narrowing of the main pancreatic duct.

Clinical characteristics of autoimmune pancreatitis: An analysis of 7 cases

AIM: To analyze and summarize the clinical characteristics of autoimmune pancreatitis (AIP) for the purpose of improving its diagnosis and treatment.

METHODS: The clinical data for 7 patients with autoimmune pancreatitis who were hospitalized in the past two years were analyzed retrospectively.

RESULTS: Main clinical manifestations were obstructive jaundice in 7 cases (100%), mild abdominal pain or epigastric discomfort in 3 cases (42.9%), weakness or weight loss in 5 cases (71.4%), diarrhea in 3 cases (42.9%), abdominal distension in 2 cases (28.6%), and dyspepsia in 2 cases (28.6%). All 7 patients had elevated serum gamma globulins (100%). Six (85.7%) patients had elevated serum IgG, aminotransferase and FBG, and four patients had elevated CAl99 (57.1%). Two (28.6%) patients tested positive for RF and AMA, and three (42.9%) positive for ANA. Diffuse or localized enlargement of the pancreas was revealed by B ultrasound in 4 cases and CT in 6 cases. MRCP showed narrowing of the pancreatic section of the common bile duct in 6 cases. ERCP demonstrated narrowing of the pancreatic section of the common bile duct and the head segment of the main pancreatic duct in 4 cases. Six patients underwent steroid therapy, which was effective in all patients. Three out of six cases (including 2 cases without sufficient course of treatment) recurred and turned better after receiving steroid therapy again. Jaundice relieved in three cases after ERCP-guided common bile duct stent implantation.

CONCLUSION: The clinical manifestations of AIP show some characteristics. Accurate diagnosis and treatment of AIP rely on clinical symptoms, imaging features, serum examinations and response to steroid therapy.

Autoimmune pancreatitis: current concepts

Autoimmune pancreatitis (AIP) is a distinct type of chronic pancreatitis with unique clinical, pathological, serological, and imaging features. AIP usually presents with obstructive jaundice. Imaging studies often reveal enlargement of the pancreas with a pancreatic mass and strictures of the main pancreatic duct. Two subtypes of AIP have recently been identified. Type I AIP is more prevalent in elderly Asian males and is characterized by lymphoplasmacytic sclerosing pancreatitis, obliterative phlebitis, and infiltration of large numbers of IgG4-positive plasma cells. Type II AIP is more prevalent in Caucasians and is characterized by granulocyte epithelial lesions. Most patients with type I AIP have a significantly elevated serum IgG4 concentration, which is an important feature for diagnosis and for differentiating between AIP and other conditions such as pancreatic cancer. Extrapancreatic complications are common, such as sclerosing cholangitis, sclerosing sialadenitis, retroperitoneal fibrosis in type I AIP, and ulcerative colitis in type II AIP. A rapid response to glucocorticoids treatment is suggestive of AIP, but the relapse rate is high, warranting the use of immunosuppressant treatment. B-cell depletion with rituximab may be a promising therapy. The prognosis of AIP is generally benign if treated promptly, and spontaneous remission occurs in a proportion of patients.

Current concept and diagnosis of IgG4-related disease in the hepato-bilio-pancreatic system

Recently, IgG4-related disease (IgG4-RD) has been recognized as a novel clinical entity with multiorgan involvement and unknown origin, associated with abundant infiltration of IgG4-positive cells. The Japanese research committee, supported by the Ministry of Health, Labor and Welfare of Japan, unified many synonyms for these conditions to the term "IgG4-RD" in 2009. The international symposium on IgG4-RD endorsed the comprehensive nomenclature as IgG4-RD, and proposed the individual nomenclatures for each organ system manifestations in 2011. Although the criteria for diagnosing IgG4-RD have not yet been established, proposals include the international pathological consensus (IPC) and the comprehensive diagnostic criteria (CDC) for IgG4-RD for general use, and several organ-specific criteria for organ-specialized physicians, e.g., the International consensus diagnostic criteria (ICDC) and the revised clinical diagnostic criteria in 2011 by the Japan Pancreas Society (JPS-2011) for type1 AIP; the Clinical Diagnostic Criteria 2012 for IgG4-sclerosing cholangitis (IgG4-SC-2012); the diagnostic criteria for IgG4-positive Mikulicz's disease by the Japanese Society for Sjogren's syndrome; and diagnostic criteria for IgG4-related kidney disease by the Japanese Society of Nephrology. In cases of probable or possible IgG4-RD diagnosed by the CDC, organ-specific diagnostic criteria should be concurrently used according to a diagnosis algorithm for IgG4-RD, with referral to a specialist.

Cholangiocarcinoma or IgG4-associated cholangitis: how feasible it is to avoid unnecessary surgical interventions?

OBJECTIVE

To evaluate the experience of a tertiary hepatopancreaticobiliary (HPB) center in the diagnostic approach and management of patients with suspicion of cholangiocarcinoma (CCa), focusing on excluding patients with IgG4-associated cholangitis (IAC) from unnecessary major surgical interventions.

METHODS

Between January 2008 and September 2010, a total number of 152 patients with suspicion of CCa underwent evaluation through a HPB multidisciplinary team meeting. Patients without tissue diagnosis were managed surgically or medically on the basis of probable presence of IAC as underlying pathology. Serology, immunostaining, and imaging were reviewed and analyzed according to the HISORt (Histology, Imaging, Serology, Other organ involvement, Response to therapy) criteria for IAC.

RESULTS

Tissue diagnosis during the diagnostic workup was achieved in 104 patients (68%), whereas the remaining 48 were classified as "highly suspicious for CCa" (n = 35) or as "probable IAC" (n = 13). Among 16 "highly suspicious for CCa" patients who underwent surgery, pathology revealed 2 patients harboring IAC (n = 1) and a benign chronic inflammatory biliary stricture (n = 1), respectively. Among the 13 patients with primarily medical management as "probable IAC," final diagnosis was CCa (n = 3) and IAC (n = 9), while 1 patient had no proven diagnosis. The accuracy of serum IgG4 for diagnosis of IAC reached 60%. Sensitivity and specificity of immunostaining for IAC in biopsy specimens were 56% and 89%, respectively. Imaging features suggesting IAC yielded sensitivity, specificity, and accuracy of 75%, 89%, and 83%, respectively. Initial imaging was revised at the referral institute in 75% of IAC patients (P = 0.009), while an isolated stricture (P = 0.038), a biliary mass (P = 0.006), and normal pancreas on computed tomography (P = 0.01) were statistically significant parameters for distinguishing between CCa and IAC. The mean time for establishing a diagnosis of IAC was 12.4 months (range: 2.5-32 months).

CONCLUSIONS

Differential diagnosis between CCa and IAC mandates high index of suspicion and low threshold for referral in high volume institutes. The delayed establishment of diagnosis particularly for CCa needs to be balanced versus avoiding unnecessary surgery for IAC. Imaging features may be most helpful for optimal management.

Autoimmune pancreatitis: an illustrated guide to diagnosis

Autoimmune pancreatitis (AIP) remains one of the rarer forms of pancreatitis but has become increasingly well recognized and widely diagnosed as it is an important differential, particularly due to the dramatic response to appropriate therapy. It is now best considered as part of a multisystem disease and the notion of "IgG4-related systemic sclerosing disease" has become widely recognized as the number of extra-pancreatic associations of AIP grows. More recently AIP has been classified into two subtypes: lymphoplasmacytic sclerosing pancreatitis (LPSP) and idiopathic duct-centric pancreatitis (IDCP) with distinct geographical, age and sex distributions for the two subtypes, in addition to different pathological characteristics. The role of imaging is crucial in AIP and should be considered in conjunction with clinical, serological, and histopathological findings to make the diagnosis. Radiologists are uniquely placed to raise the possibility of AIP and aid the exclusion of significant differentials to allow the initiation of appropriate management and avoidance of unnecessary intervention. Radiological investigation may reveal a number of characteristic imaging findings in AIP but appearances can vary considerably and the focal form of AIP may appear as a pancreatic mass, imitating pancreatic carcinoma. This review will illustrate typical and atypical appearances of AIP on all imaging modes. Emphasis will be placed on the imaging features that are likely to prove useful in discriminating AIP from other causes prior to histopathological confirmation. In addition, examples of relevant differential diagnoses are discussed and illustrated.

Autoimmune pancreatitis and non-necrotizing acute pancreatitis: computed tomography pattern

OBJECTIVES

To retrospectively differentiate diffuse autoimmune pancreatitis from non-necrotizing acute pancreatitis at clinical onset with multi detector row computed tomography.

METHODS

36 Patients suffering from diffuse autoimmune pancreatitis (14) or non-necrotizing acute pancreatitis (22) were enrolled. Qualitative analysis included stranding, retroperitoneal fluid film, capsule-like rim enhancement and pleural effusion. In quantitative analysis pancreatic density was measured in all phases. The vascularization behaviour was assessed using the relative enhancement rate across all phases.

RESULTS

Pancreatic density resulted lower in non-necrotizing acute pancreatitis compared to diffuse autoimmune pancreatitis patients in pre-contrast phase and higher in pancreatic phase. Relative enhancement rate evaluation confirmed different vascularization behaviours of the two diseases. Only non-necrotizing acute pancreatitis Patients presented peripancreatic stranding and fluid in the retromesenteric interfascial plane.

CONCLUSIONS

Multi detector row computed tomography is a useful technique for differentiating diffuse autoimmune pancreatitis from non-necrotizing acute pancreatitis at clinical onset. Peripancreatic stranding and retroperitoneal fluid film, characteristic of non-necrotizing acute pancreatitis, and late-phase peripheral rim enhancement, characteristic of diffuse autoimmune pancreatitis, provide qualitative clues to the differentiation. A quantitative study of contrast enhancement patterns, considering the relative enhancement rate, can assist in the differential diagnoses of two diseases.

Autoimmune pancreatitis (AIP) type 1 and type 2: an international consensus study on histopathologic diagnostic criteria

OBJECTIVES

To develop and validate histologic diagnostic criteria for autoimmune pancreatitis (AIP) and its types.

METHODS

Thirteen pathologists participated in this 2-phase study to develop diagnostic criteria for AIP types 1 and 2 (phase 1) and validate them (phase 2). A virtual library of 40 resected pancreata with AIP and other forms of chronic pancreatitis (CP) was constructed. Readers reviewed the slides online and filled out a questionnaire for histopathologic findings and diagnosis.

RESULTS

Diagnostic criteria for AIP and its types were proposed according to the results from the top 5 reviewers in phase 1. The interobserver agreement was significantly improved in phase 2 by applying the proposed diagnostic criteria. Features distinguishing AIP from alcoholic and obstructive forms of CP were periductal lymphoplasmacytic infiltrate, inflamed cellular stroma with storiform fibrosis, obliterative phlebitis, and granulocytic epithelial lesions. Although there was overlap, 2 types of AIP were recognized. Type 1 had dense lymphoplasmacytic infiltrate with storiform fibrosis and obliterative phlebitis, whereas type 2 was distinguished from type 1 by the presence of granulocytic epithelial lesions.

CONCLUSIONS

Autoimmune pancreatitis can be distinguished from other forms of CP with substantial interobserver agreement. The 2 types of AIP can be distinguished by the proposed consensus histopathologic diagnostic criteria.

Autoimmune pancreatitis

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

Pancreatitis, Other Inflammatory Lesions, and Pancreatic Pseudotumors

The pancreas is versatile in the diversity of disorders that it can exhibit. In this article, characteristics of disorders such as chronic, autoimmune, eosinophilic, hereditary, and infectious pancreatitis are described. With regard to autoimmune pancreatitis, the role of clinical evaluation, histologic examination, and IgG4 immunohistochemistry is discussed. The role of pancreatitis in the pathogenesis of diabetes is also mentioned. Some implications of pancreatitis are highlighted, including the neoplastic predisposition caused by inflammatory lesions of the pancreas. The goal of this article is to convey an appreciation of these disorders because their recognition can benefit patients tremendously, as inflammatory lesions of the pancreas can be mass-forming, giving rise to pseudotumors, and leading to surgical resection that may otherwise be unnecessary.

International consensus diagnostic criteria for autoimmune pancreatitis: guidelines of the International Association of Pancreatology

OBJECTIVES

To achieve the goal of developing international consensus diagnostic criteria (ICDC) for autoimmune pancreatitis (AIP).

METHODS

An international panel of experts met during the 14th Congress of the International Association of Pancreatology held in Fukuoka, Japan, from July 11 through 13, 2010. The proposed criteria represent a consensus opinion of the working group.

RESULTS

Autoimmune pancreatitis was classified into types 1 and 2. The ICDC used 5 cardinal features of AIP, namely, imaging of pancreatic parenchyma and duct, serology, other organ involvement, pancreatic histology, and an optional criterion of response to steroid therapy. Each feature was categorized as level 1 and 2 findings depending on the diagnostic reliability. The diagnosis of type 1 and type 2 AIP can be definitive or probable, and in some cases, the distinction between the subtypes may not be possible (AIP-not otherwise specified).

CONCLUSIONS

The ICDC for AIP were developed based on the agreement of an international panel of experts in the hope that they will promote worldwide recognition of AIP. The categorization of AIP into types 1 and 2 should be helpful for further clarification of the clinical features, pathogenesis, and natural history of these diseases.

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

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

Magnetic resonance cholangiopancreatography for the diagnostic evaluation of autoimmune pancreatitis

OBJECTIVE

The aim of this study was to determine the role of magnetic resonance cholangiopancreatography (MRCP) for diagnosing autoimmune pancreatitis (AIP) and the accuracy of MRCP in depicting the main pancreatic duct (MPD) morphology of AIP using endoscopic retrograde cholangiopancreatography (ERCP) as the reference standard.

METHODS

Thirty-eight AIP patients, 40 pancreatic cancer patients, and 40 patients with normal pancreas were included. MRCP was interpreted in association with cross-sectional magnetic resonance images regarding MPD morphology, pancreatic parenchyma, and extrapancreatic abnormalities. Main pancreatic duct was interpreted as narrowed when a narrowed-appearing segment on MRCP was associated with upstream dilatation or pancreatic parenchymal abnormalities in the same location.

RESULTS

Accuracy of MRCP for depicting MPD morphology of AIP (64.7% [22/34]) was lower than those for pancreatic cancer (88.5% [23/26]) (P = 0.041) or normal pancreas (100% [40/40]) (P < 0.0005). The inaccuracy in AIP was primarily (10/12) due to overestimation of MPD narrowing. Of various differing MRCP findings between AIP and pancreatic cancer, multiple MPD narrowing (AIP vs cancer, 27/38 vs 0/40) and upstream MPD dilatation greater than 5 mm in diameter (AIP vs cancer, 0/38 vs 10/40) could exclude pancreatic cancer and AIP, respectively.

CONCLUSIONS

MRCP cannot replace ERCP for the diagnostic evaluation of AIP but may deserve to be used when ERCP has been unsuccessful or is difficult to perform.

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

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

IgG4 immunostaining of duodenal papillary biopsy specimens may be useful for supporting a diagnosis of autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis (AIP) is now considered to be part of an immunoglobulin G4 (IgG4)-related systemic fibroinflammatory disease.

OBJECTIVE

We evaluated whether IgG4 immunostaining of duodenal papillary biopsy specimens is useful for supporting a diagnosis of AIP.

DESIGN

A prospective study.

SETTING

A tertiary academic center.

PATIENTS/INTERVENTIONS

We obtained 2 forceps biopsy specimens from the major duodenal papilla (MDP) of 19 symptomatic AIP patients during ERCP before steroid administration. As a control, biopsy specimens were obtained from the MDP of patients with pancreatic cancer (n = 35), cholangiocarcinoma (n = 20), ampullary cancer (n = 11), ordinary chronic pancreatitis (n = 18), and AIP in remission (n = 16) and immunohistochemically examined.

MAIN OUTCOME MEASUREMENTS

Specimens were considered positive for IgG4 immunostaining if there were more than 10 IgG4-positive plasma cells per high-power field.

RESULTS

Positive IgG4 immunostaining of the MDP was found in 10 (53%) of 19 symptomatic AIP patients, but was absent in the control groups. Among symptomatic AIP patients (n = 19), 5 (83%) of 6 AIP patients with elevated serum IgG4 levels exhibited positive IgG4 staining of the MDP, whereas 5 (38%) of 13 AIP patients with normal serum IgG4 levels showed positive IgG4 staining of the MDP. Nine of 19 symptomatic AIP patients also underwent pancreatic biopsy, and positive IgG4 immunostaining of the MDP was observed in patients with positive pancreas IgG4 staining (4/6, 67%), but not in patients with negative pancreas IgG4 staining (0/3).

LIMITATIONS

Small symptomatic AIP patient population.

CONCLUSIONS

Positive IgG4 immunostaining of the MDP was an extremely specific and moderately sensitive tool for the diagnosis of AIP. IgG4 immunostaining of the MDP may be useful for supporting a diagnosis of AIP, especially when AIP is suspected clinically but serum IgG4 levels are normal or pancreatic tissue is not available.

A case of IgG4-related sclerosing disease with retroperitoneal fibrosis, autoimmune pancreatitis and bilateral focal nephritis

A 74-year-old male patient presented with progressive anorexia, cholestatic liver function tests, and a diffuse enlarged pancreas suggestive of a pancreatic carcinoma. There was a marked elevation of total immunoglobulin G4 (IgG4) in serum. Further investigation led to the diagnosis of IgG4-related sclerosing disease with involvement of the pancreas, retroperitoneal fibrosis, and bilateral focal nephritis. To our knowledge, this is the first report on these 3 clinical entities occurring in the same patient.A short review of the literature concerning autoimmune pancreatitis and retroperitoneal fibrosis is made, with special interest to the concept of IgG4-related pathology. This systemic disease can have several clinical manifestations: IgG4-positivity not only can be found in the pancreas, but also at the level of extrahepatic biliary ducts, gallbladder, salivary glands, retroperitoneal tissue, kidneys, ureters, and lymph nodes. Although further investigation is required to determine its exact pathophysiologic role, IgG4 seems to be an important key player.

Utility of 18F-FDG PET/CT for differentiation of autoimmune pancreatitis with atypical pancreatic imaging findings from pancreatic cancer

OBJECTIVE

This study was conducted to evaluate the clinical usefulness of PET/CT in differentiating autoimmune pancreatitis from pancreatic cancer.

MATERIALS AND METHODS

To differentiate autoimmune pancreatitis from pancreatic cancer, we analyzed the cases of 17 patients with autoimmune pancreatitis and atypical pancreatic imaging findings who underwent integrated PET/CT. The PET/CT findings on the 17 patients with autoimmune pancreatitis were compared with those of 151 patients with pancreatic cancer.

RESULTS

Fluorine-18 FDG uptake by the pancreas was found in all patients with autoimmune pancreatitis and in 82% (124/151) of patients with pancreatic cancer. Diffuse uptake by the pancreas was significantly more frequent in patients with autoimmune pancreatitis (53% vs 3%, p < 0.001). FDG uptake by the salivary glands and kidneys was seen only in patients with autoimmune pancreatitis, the former reaching statistical significance (p = 0.003). Follow-up PET/CT after steroid therapy was performed for eight patients with autoimmune pancreatitis. After steroid therapy, none of the patients had intense FDG uptake by the pancreas or extrapancreatic organs.

CONCLUSION

In difficult cases, at PET/CT the presence of diffuse uptake of FDG by the pancreas or concomitant extrapancreatic uptake by the salivary glands can be used to aid in differentiation of autoimmune pancreatitis and pancreatic cancer.

Autoimmune pancreatitis: differences between the focal and diffuse forms in 87 patients

OBJECTIVES

Autoimmune pancreatitis (AIP) is a particular type of chronic pancreatitis that can be classified into diffuse and focal forms. The aim of this study was to analyze clinical and instrumental features of patients suffering from the diffuse and focal forms of AIP.

METHODS

AIP patients diagnosed between 1995-2008 were studied.

RESULTS

A total of 87 AIP patients (54 male and 33 female patients, mean age 43.4+/-15.3 years) were studied. Focal-type AIP was diagnosed in 63% and diffuse-type in 37%. Association with autoimmune diseases was observed in 53% of cases, the most common being ulcerative colitis (30%). Serum levels of IgG4 exceeded the upper normal limits (135 mg/dl) in 66% of focal AIP and in 27% of diffuse AIP (P=0.006). All patients responded to steroids. At recurrence non-steroid immunosuppressive drugs were successfully used in six patients. Recurrences were observed in 25% of cases, and were more frequent in focal AIP (33%) than in diffuse AIP (12%) (P=0.043), in smokers than in non-smokers (41% vs. 15%; P=0.011), and in patients with pathological serum levels of IgG4 compared to those with normal serum levels (50% vs. 12%; P=0.009). In all, 23% of the patients underwent pancreatic resections. Among patients with focal AIP, recurrences were observed in 30% of operated and in 34% of not operated patients.

CONCLUSIONS

Focal-type and diffuse-type AIP differ as regards clinical symptoms and signs. Recurrences occur more frequently in focal AIP than in diffuse AIP. The use of non-steroid immunosuppressants may be a therapeutic option in relapsing AIP.