Autoimmune pancreatitis: pancreatic and extrapancreatic imaging findings. AJR Am J Roentgenol. 2009;192:431-437. [PMID: 19155406 DOI: 10.2214/ajr.07.2956]

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.

Analysis of Clinical, Serological, and Imaging Features of Autoimmune Pancreatitis and a Case-Control Study on Prognostic Factors in Response to Hormone Therapy

Objective

The paper aimed to analyze the clinical, serological, and imaging features of autoimmune pancreatitis (AIP) and the prognostic factors affecting hormone therapy.

Methods

A total of 106 patients with AIP enrolled in our hospital from March 2016 to August 2018 were treated with the hormone. The curative effect and recurrence were followed up. The patients were divided into relapse group (n = 42) and nonrelapse group (n = 64) according to the recurrence within 3 years after initial hormone therapy. The symptoms and signs, laboratory examination, and treatment were compared, and binary logistic regression was employed to explore the risk factors of AIP recurrence.

Results

Among the 106 patients included in this study, there were 78 males and 28 females, with a male-to-female ratio of 3:1. The average age of onset was 56.25 ± 8.87 years; the minimum age was 39 years; and the maximum age was 7 years. The main clinical symptoms were jaundice (67.92%), abdominal pain (48.11%), and abdominal distension (33.96%). In addition, there were symptoms of weight loss, nausea, vomiting, itching, and gray stool. Previous complications included 27.35% diabetes (29/106), 22.64% hypertension (24/106), 35.84% smoking (38/106), and 28.30% alcohol consumption (30/106). The serological characteristics were mainly the increase in serum IgG4 level; 92.45% (98/106) level was higher compared to the upper limit of normal value; the median level was 11.65 g/L; and the highest level was 35.79 g/L. A total of 88.67% (94/106) had an abnormal liver function. The results of imaging examination indicated that 58.49% (62/106) of extrapancreatic organs were involved, of which 46.22% (49/106) were the most common bile duct involvement. All the patients in the group reached a state of remission after hormone treatment. After the disease was relieved, the patients were followed up for 3 years. The recurrence rate was 39.62% (42/106), and the median time of recurrence (month) was 9 (range 2–36). The recurrence rates within 1, 2, and 3 years were 20.75%, 31.13%, and 39.62%, respectively. Among the recurrent patients, 52.38% (22/42) relapsed within 1 year, 78.57% (33/42) within 2 years, and 100.00% (42/42) within 3 years. Multivariate analysis showed that the short duration of glucocorticoid therapy and involvement of extrapancreatic organs were risk factors for relapse after glucocorticoid therapy in patients with type I AIP.

Conclusion

Type 1 AIP is more common in middle-aged and elderly men. The clinical symptoms of jaundice, abdominal pain, and abdominal distension are common, often accompanied by involvement of extrapancreatic organs, of which bile duct involvement is the most common. Type 1 AIP glucocorticoid treatment acceptance and disease remission are better, but the recurrence rate is higher after glucocorticoid treatment. Patients with a short time of glucocorticoid treatment and involvement of extrapancreatic organs may have a higher risk of recurrence.

Autoimmune pancreatitis presenting as a pancreatic head mass

The diagnosis of autoimmune pancreatitis (AIP) is often difficult as the main differential diagnosis is pancreatic head adenocarcinoma. Some clinical, radiological, serological and histological criteria help in guiding the diagnosis. The serum gamma-globulin IgG4 dosage is the most sensitive and specific marker. The shape of the ductal stenosis in AIP is characteristic. The treatment is based on corticosteroids. We report the case of a 53-year-old woman, presenting with pancreatic head mass mimicking an adenocarcinoma.

Pancreatic Neuroendocrine Tumor presenting as a diffuse pancreatic enlargement, case report and review of literature

Pancreatic neuroendocrine tumors are rare neoplasms that comprise 1-2% of all pancreatic tumors. However, they are the second most common solid pancreatic neoplasms. They have a wide range of imaging appearances and they can show common to very rare imaging presentations. Most of the time they are solitary well-marginated enhancing solid mass arising in a certain aspect of the pancreas. We present a case report of a 41-year-old female who underwent clinical work-up for abdominal pain, loss of appetite and weight loss for the past year. Ultrasound, computed tomography, and magnetic resonance imaging show diffuse homogenous pancreatic enlargement without contour deformity or a focal mass. Lymphoma and autoimmune pancreatitis were suggested based on imaging findings but IGg4 level and other lab data were normal. Endoscopic ultrasonography confirmed the diffuse enlargement of the pancreas without peripheral structures involvement. The pathological results of multiple fine-needle aspiration biopsy from all parts of the enlarged pancreas revealed a low-grade neuroendocrine tumor.

Meta-analysis of CT and MRI for differentiation of autoimmune pancreatitis from pancreatic adenocarcinoma

OBJECTIVES

To systematically determine the diagnostic performance of computed tomography (CT) and magnetic resonance imaging (MRI) for differentiating autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC), with a comparison between the two imaging modalities.

METHODS

Literature search was conducted using PubMed and EMBASE databases to identify original articles published between 2009 and 2019 reporting the diagnostic performance of CT and MRI for differentiating AIP from PDAC. The meta-analytic sensitivity and specificity of CT and MRI were calculated, and compared using a bivariate random effects model. Subgroup analysis for differentiating focal AIP from PDAC was performed.

RESULTS

Of the 856 articles screened, 11 eligible articles are remained, i.e., five studies for CT, four for MRI, and two for both. The meta-analytic summary sensitivity and specificity of CT were 59% (95% confidence interval [CI], 41-75%) and 99% (95% CI, 88-100%), respectively, while those of MRI were 84% (95% CI, 68-93%) and 97% (95% CI, 87-99%). MRI had a significantly higher meta-analytic summary sensitivity than CT (84% vs. 59%, p = 0.02) but a similar specificity (97% vs. 99%, p = 0.18). In the subgroup analysis for focal AIP, the sensitivity for distinguishing between focal AIP and PDAC was lower than that for the overall analysis. MRI had a higher sensitivity than CT (76% vs. 50%, p = 0.28) but a similar specificity (97% vs. 98%, p = 0.07).

CONCLUSION

MRI might be clinically more useful to evaluate patients with AIP, particularly for differentiating AIP from PDAC.

KEY POINTS

• MRI had an overall good diagnostic performance to differentiate AIP from PDAC with a meta-analytic summary estimate of 83% for sensitivity and of 97% for specificity. • CT had a very high specificity (99%), but a suboptimal sensitivity (59%) for differentiating AIP from PDAC. • Compared with CT, MRI had a higher sensitivity, but a similar specificity.

Autoimmune pancreatitis type 2

PURPOSE OF REVIEW

Type 2 autoimmune pancreatitis (AIP) is a rare inflammatory disease of the pancreas. Very few data have been published on this particular subtype, which differs from the 'classical' IgG4-related type 1 AIP in terms of pathological features, epidemiology and risk of relapse. The aim of the current review is to summarize the available literature, suggesting a diagnostic and therapeutic approach to this disease.

RECENT FINDINGS

Based on the International Consensus Diagnostic Criteria, to achieve a 'definitive' diagnosis of type 2 AIP, histology is required. If a definitive histological diagnosis is lacking (not-performed or inconclusive), concomitant presence of inflammatory bowel disease (IBD) and effective response to steroids are needed for a 'probable' diagnosis of type 2 AIP.

SUMMARY

Type 2 AIP is a selective pancreatic disease, without association to other organ involvement. The lack of validated serological markers makes the diagnosis challenging in clinical practice, particularly in focal forms. A careful evaluation of the clinical profile (especially of a concomitant IBD), associated with an accurate imaging, might help in clinical practice to suspect type 2 AIP. Response to steroids is crucial to achieve diagnosis in patients without a diagnostic histology.

IgG4-related disease in the abdomen and pelvis: atypical findings, pitfalls, and mimics

IgG4-related disease (IgG4-RD) is a systemic, autoimmune, fibroinflammatory disease that can cause multi-organ damage. Although there have been many trials and studies since its recognition in 2003, there is still much that is unknown. Furthermore, IgG4-RD can affect any organ in the body and often has many mimics and alternative diagnoses, which can make for a challenging workup. Imaging plays a substantial role in the diagnosis of IgG4-RD and is often the first occasion where IgG4-RD comes into consideration. Thus, knowledge about the imaging findings of various manifestations of IgG4-RD can aid in the diagnosis and have a significant impact on patient management. In this article, we review the wide array of imaging findings, both typical and atypical, as well as possible mimics of IgG4-RD in the abdomen and pelvis.

Duct-obstructive pancreatitis with granulocytic epithelial lesion in a patient with ulcerative colitis: An atypical manifestation of type 2 autoimmune pancreatitis?

Type 2 autoimmune pancreatitis (AIP) typically presents with diffuse or focal enlargement of the pancreas; however, its diverse clinical presentation has not yet been clarified. We herein described a 46-year-old man with a 1-month history of ulcerative colitis who presented with imaging features of a mass-like lesion in the pancreatic body with upstream duct dilatation and serum CA19-9 elevation. He underwent laparoscopic distal pancreatectomy with splenectomy for suspected malignancy. Histologically, the area radiologically suspected to be duct dilatation consisted of necrotic tissue, in which the disrupted main pancreatic duct was involved. The area radiologically suspected to be the mass lesion showed features of pancreatitis without discrete mass. In addition, several ducts showed neutrophilic duct injury similar to granulocytic epithelial lesions observed in type 2 AIP. Immunohistochemistry revealed the aberrant expression of IL-8 in the pancreatic ductules and infiltrating CD3-positive T-lymphocytes, findings recently identified in type 2 AIP. The present case is not typical for either type 2 AIP or other known conditions, but extreme examples of type 2 AIP may present with ductal obstruction because of severe neutrophilic duct injury. IL-8 immunostaining may also assist in establishing a diagnosis of type 2 AIP with an atypical presentation.

Usefulness of non-contrast MR imaging in distinguishing pancreatic ductal adenocarcinoma from focal pancreatitis

BACKGROUND

Accurate differentiation between pancreatic adenocarcinoma and focal pancreatitis is challenging.

PURPOSE

To investigate the usefulness of non-contrast MRI by comparing with multidetector row CT (MDCT) and gadoxetic acid-enhanced MRI in the discrimination of pancreatic ductal adenocarcinoma (PDAC) and focal pancreatitis (FP).

MATERIALS AND METHODS

This retrospective study included 187 patients (116 with PDACs and 71 with FP) who underwent gadoxetic acid-MRI and MDCT prior to surgical resection or biopsy. The MRI features of PDAC and FP were compared by two radiologists. Then, two observers independently reviewed the three imaging sets: MDCT, non-contrast MRI (T1-, T2-weighted, and diffusion-weighted images), and MRI with and without gadoxetic acid to determine the diagnostic performances of each imaging modality in the discrimination of PDAC and FP.

RESULTS

The significant features on non-contrast MRI for diagnosis of PDAC included peritumoral cyst, pancreatic duct cut-off, clear hypointensity on T1WI, and bile duct dilatation (P < 0.05). Presence of peritumoural cyst showed the highest odds ratio for predicting PDAC. Non-contrast MRI was superior to MDCT in differentiating PDAC from FP with regard to accuracy (84.5% vs 95.5% for observer 1; 85.8% vs. 96.0% for observer 2), sensitivity (83.6% vs. 98.3%; 84.5% vs 97.8%), and negative predictive value (76.3% vs. 97.0%; 77.6% vs 96.4%) (P < 0.05). We found similar diagnostic values between the non-contrast MRI and MRI with and without contrast (P > 0.05) for both observers.

CONCLUSION

Non-contrast MRI is better than MDCT and comparable to MRI with and without gadoxetic acid in differentiating PDAC from FP.

Interpreting body MRI cases: classic findings in abdominal MRI

Few things in radiology are "pathognomonic" in their appearance or presentation. However, having an awareness of those findings which are specific to a certain entity is important when interpreting imaging studies. These classic findings can be identified with many imaging modalities, but no modality provides as many recognizable observations as an MRI. This results from the large variety of pulse sequences that provide high contrast resolution, prior to and following contrast administration. In this article, the most classically recognized abdominal findings are presented including the following: Liver: Cyst, hemangioma, focal nodular hyperplasia, hepatic adenoma, hemosiderosis, hepatocellular carcinoma. Spleen: Cyst, hemangioma, lymphangioma, hemosiderosis, Gandy-Gamna bodies. Biliary system: Biliary stones and choledocholithiasis, pneumobilia, choledochal cyst. Gallbladder: Adenomyomatosis, sludge, surgical clips in the gallbladder fossa. Pancreas: Pancreatic divisum, intraductal papillary mucinous neoplasm, pseudocyst, autoimmune pancreatitis, chronic pancreatitis, adenocarcinoma. Kidneys: Simple cyst, hemorrhagic cyst, renal sinus cyst, angiomyolipoma, solid mass.

Autoimmune pancreatitis: Imaging features

Background and Objectives

Autoimmune pancreatitis (AIP) remains a difficult disease to diagnose before treatment, particularly if presenting as a focal mass lesion. The purpose of this multicenter retrospective study is to analyze imaging features of histologically confirmed AIP to determine the additional diagnostic value of contrast-enhanced ultrasound (CEUS), contrast-enhanced endoscopic ultrasound (CE-EUS), and elastography to B-mode features.

Patients and Methods

We report on a retrospective data collection of 60 histologically confirmed cases of AIP in comparison to 16 patients with pancreatic adenocarcinomas (PDAC). All CE (-E) US examinations were assessed by two independent readers in consensus. The role of CEUS and CE-EUS for pancreatic evaluation was defined according to the 2011 European Federation of Societies for Ultrasound in Medicine and Biology guidelines.

Results

After injection of ultrasound (US) contrast agents, most AIP lesions displayed focal or diffuse isoenhancement (86.6%) in the arterial phase, while most of the PDAC lesions (93.7%) were hypoenhancing (P < 0.01). During the late phase, most AIP lesions were hyper-(65%) or iso-enhancing (35%), while most PDAC lesions were hypoenhancing (93.7%). CE-EUS was performed in a subset of ten patients and showed hyperenhancement in all AIP cases. Most focal AIP lesions (n = 27, 79.4%) were stiffer than the surrounding pancreatic parenchyma.

Conclusions

In this study, percutaneous and endoscopic contrast enhanced harmonic US techniques consistently revealed diffuse and focal types of AIP to have features consistent with vascularized lesions. Differentiation from the typically hypovascularized pancreatic adenocarcinoma was possible with CE (-E) US evaluation.

Specialized Imaging and Procedures in Pediatric Pancreatology: A North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Clinical Report

OBJECTIVES

An increasing number of children are being diagnosed with pancreatitis and other pancreatic abnormalities. Dissemination of the information regarding existing imaging techniques and endoscopic modalities to diagnose and manage pancreatic disorders in children is sorely needed.

METHODS

We conducted a review of the medical literature on the use of the following imaging and procedural modalities in pediatric pancreatology: transabdominal ultrasonography (TUS), computed tomography (CT), magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP), endoscopic ultrasonography (EUS), and endoscopic retrograde cholangiopancreatography (ERCP). Recommendations for current use and future research were identified.

RESULTS

TUS offers noninvasive images of the pancreas but has limitations to details of parenchyma and ductal structures. CT offers improved detail of pancreatic parenchyma, solid masses, and traumatic injuries, but requires relatively high levels of ionizing radiation and does not adequately assess ductal anatomy. MRI/MRCP offers detailed intrinsic tissue assessment and pancreatic ductal characterization, but requires longer image acquisition time and is relatively poor at imaging calcifications. EUS provides excellent evaluation of pancreatic parenchyma and ductal anatomy, but can be subjective and operator dependent and requires sedation or anesthesia. EUS offers the capacity to obtain tissue samples and drain fluid collections and ERCP offers the ability to improve drainage by performing sphincterotomy or placing pancreatic stents across duct injuries and strictures.

CONCLUSIONS

Various imaging modalities may be used in pediatric pancreatology, but TUS and MRI/MRCP are favored. Interventional therapeutic maneuvers primarily involve use of ERCP and EUS. Future research is necessary to optimize equipment, expertise, and appropriate indications.

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.

[Autoimmune pancreatitis: An update]

CLINICAL/METHODICAL ISSUE

Autoimmune pancreatitis (AIP) is a rare disease, the pathophysiological understanding of which has been greatly improved over the last years. The most common form, type 1 AIP belongs to the IgG4-related diseases and must be distinguished from type 2 AIP, which is a much rarer entity associated with chronic inflammatory bowel disease. Clinically, there is an overlap with pancreatic cancer. Imaging and further criteria, such as serological and histological parameters are utilized for a differentiation between both entities in order to select the appropriate therapy and to avoid the small but ultimately unnecessary number of pancreatectomies.

PERFORMANCE

The diagnostics of AIP are complex, whereby the consensus criteria of the International Association of Pancreatology have become accepted as the parameters for discrimination. These encompass five cardinal criteria and one therapeutic criterion. By applying these criteria AIP can be diagnosed with a sensitivity of 84.9%, a specificity of 100% and an accuracy of 93.8%.

ACHIEVEMENTS

The diagnosis of AIP is accomplished by applying several parameters of which two relate to imaging. As for the routine diagnostics of the pancreas these are ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI). Important for the differential diagnosis is the exclusion of signs of local and remote tumor spread for which CT and MRI are established. The essential diagnostic parameter of histology necessitates sufficient sample material, which cannot usually be acquired by a fine needle biopsy. CT or MRI are the reference standard methods for identification of the optimal puncture site and imaging-assisted (TruCut) biopsy.

PRACTICAL RECOMMENDATIONS

In patients presenting with unspecific upper abdominal pain, painless jaundice combined with the suspicion of a pancreatic malignancy in imaging but a mismatch of secondary signs of malignancy, AIP should also be considered as a differential diagnosis. As the diagnosis of AIP only partially relies on imaging radiologists also have to be aware of the clinical, serological and histological parameters for AIP in order to guide clinicians towards the correct diagnosis. Only in this way can the highly efficient steroid therapy be initiated and otherwise possibly severe forms of therapy be avoided.

Autoimmune Pancreatitis: A Case of Atypical Radiographic Findings

Autoimmune pancreatitis (AIP) is a rare pancreatic disorder that can present as a manifestation of a broader systemic inflammatory disease known as immunoglobulin G4-related systemic disease (IGG4-RSD). AIP is divided into two subtypes based on clinical, radiological, and histological findings. The disease can be mistaken for pancreatic cancer because of overlapping clinical and radiological findings, but early recognition can help avoid unnecessary surgery. We present a case of a 65-year-old female with suspected acute gallstone pancreatitis found to have AIP based on serology, radiological findings, and response to steroids.

Imaging features of immunoglobulin G4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition that was first recognised as a systemic disease in 2003, when patients with autoimmune pancreatitis were found to have extrapancreatic manifestations. Since 2003, IgG4-RD has been described in a diverse range of other organs including the biliary tree, orbits, lacrimal glands, salivary glands, lungs, kidneys, aorta, retroperitoneum, lymph nodes, pachymeninges, prostate and pituitary gland. The disease frequently occurs in the absence of pancreatic involvement. The imaging manifestations of IgG4-RD are broad and variable depending on the organ involved. The majority of individual organ appearances are non-specific and differentiation between IgG4-RD and potentially more serious conditions is not usually possible based on radiological findings in one organ alone. However, if there are simultaneous findings typical of IgG4-RD in multiple organs then this is a key diagnostic clue and IgG4-RD should be considered as one of the main differentials. This review article examines the spectrum of imaging appearances of IgG4-RD. Increased awareness of the spectrum of radiological appearances of IgG4-RD throughout the body and subsequent consideration of the condition may potentially avoid invasive treatment and lead to more prompt corticosteroid therapy.

Autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a rare, distinct and increasingly recognized form of pancreatitis which has autoimmune features. The international consensus diagnostic criteria (ICDC) for AIP recently described two subtypes; type 1[lymphoplasmacytic sclerosing pancreatitis (LPSP)] and type 2 [idiopathic duct-centric pancreatitis (IDCP) or AIP with granulocytic epithelial lesion (GEL)]. Type 1 is the more common form of the disease worldwide and current understanding suggests that it is a pancreatic manifestation of immunoglobulin G4-related disease (IgG4-RD). In contrast, type 2 AIP is a pancreas-specific disease not associated with IgG4 and mostly without the overt extra-pancreatic organ involvement seen in type 1. The pathogenesis of AIP is not completely understood and its clinical presentation is non-specific. It shares overlapping features with more sinister pathologies such as cancer of the pancreas, which continues to pose a diagnostic challenge for clinicians. The diagnostic criteria requires a variable combination of histopathological, imaging and serological features in the presence of typical extrapancreatic lesions and a predictable response to steroids.

Magnetic resonance cholangiography: Current and future perspectives

Magnetic resonance cholangiography (MRC) has become the standard of reference for imaging of the biliary ducts. The use of three-dimensional (3D) sequences has resulted in improved spatial resolution with virtually isotropic voxel and improved signal/noise ratio. In addition to MRC images, 3D fat suppressed T1-weighted MR images should be systematically obtained to search for intrahepatic calculi. MRC plays a major role in the diagnosis of cholangiocarcinoma and assessment of its resectability. With modern MR systems the performance of MR is basically the same that of CT for evaluation of arterial and portal vein extent. MRC is a key imaging modality for the diagnosis of primary sclerosing cholangitis. Different imaging patterns may be observed including multifocal intra- and extrahepatic strictures alternating with slightly dilated ducts. Focal signal abnormality of the liver parenchyma and focal parenchymal atrophy represent the consequences of biliary duct obstruction on liver parenchyma. Diagnosis of biliary lithiasis is performed by combination of MRC and T1-weighted MR imaging. MRC can be performed for the diagnosis of secondary cholangitis including ascending cholangitis, ischemic cholangitis and IgG4-related sclerosing cholangitis. Hepatobiliary contrast agents could be used for demonstrating the site of biliary duct leakage after surgery and for functional imaging. MR imaging can also be used to determine the prognosis of PSC. The inherent limitations of MRC of bile ducts are still the suboptimal spatial resolution for evaluation of distal intrahepatic biliary ducts.

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.

Deciphering autoimmune pancreatitis, a great mimicker: case report and review of the literature

Background. Autoimmune pancreatitis (AIP) is an atypical chronic inflammatory pancreatic disease that appears to involve autoimmune mechanisms. In recent years, AIP has presented as a new clinical entity with its protean pancreaticobiliary and systemic presentations. Its unique pathology and overlap of clinical and radiological features and absence of serological markers foster the disease's unique position. We report a case of diffuse type 1 autoimmune pancreatitis with obstructive jaundice managed with biliary sphincterotomy, stent placement, and corticosteroids. A 50-year-old Caucasian woman presented to our hospital with epigastric pain, nausea, vomiting, and jaundice. Workup showed elevated liver function tests (LFT) suggestive of obstructive jaundice, MRCP done showed diffusely enlarged abnormal appearing pancreas with loss of normal lobulated contours, and IgG4 antibody level was 765 mg/dL. EUS revealed a diffusely hypoechoic and rounded pancreatic parenchyma with distal common bile duct (CBD) stricture and dilated proximal CBD and common hepatic duct (CHD). ERCP showed tight mid to distal CBD stricture that needed dilatation, sphincterotomy, and placement of stent that led to significant improvement in the symptoms and bilirubin level. Based on clinical, radiological, and immunological findings, a definitive diagnosis of AIP was made. Patient was started on prednisone 40 mg/day and she clinically responded in 4 weeks.

Adult bile duct strictures: role of MR imaging and MR cholangiopancreatography in characterization

Bile duct strictures in adults are secondary to a wide spectrum of benign and malignant pathologic conditions. Benign causes of bile duct strictures include iatrogenic causes, acute or chronic pancreatitis, choledocholithiasis, primary sclerosing cholangitis, IgG4-related sclerosing cholangitis, liver transplantation, recurrent pyogenic cholangitis, Mirizzi syndrome, acquired immunodeficiency syndrome cholangiopathy, and sphincter of Oddi dysfunction. Malignant causes include cholangiocarcinoma, pancreatic adenocarcinoma, and periampullary carcinomas. Rare causes include biliary inflammatory pseudotumor, gallbladder carcinoma, hepatocellular carcinoma, metastases to bile ducts, and extrinsic bile duct compression secondary to periportal or peripancreatic lymphadenopathy. Contrast material-enhanced magnetic resonance (MR) imaging with MR cholangiopancreatography is extremely helpful in the noninvasive evaluation of patients with obstructive jaundice, an obstructive pattern of liver function, or incidentally detected biliary duct dilatation. Some of these conditions may show characteristic findings at MR imaging-MR cholangiopancreatography that help in making a definitive diagnosis. Although endoscopic retrograde cholangiopancreatography with tissue biopsy or surgery is needed for the definitive diagnosis of many of these strictures, certain MR imaging characteristics of the narrowed segment (eg, thickened wall, long-segment involvement, asymmetry, indistinct outer margin, luminal irregularity, hyperenhancement relative to the liver parenchyma) may favor a malignant cause. Awareness of the various causes of bile duct strictures in adults and familiarity with their appearances at MR imaging-MR cholangiopancreatography are important for accurate diagnosis and optimal patient management.

Autoimmune pancreatitis: Multimodality non-invasive imaging diagnosis

Autoimmune pancreatitis (AIP) is characterized by obstructive jaundice, a dramatic clinical response to steroids and pathologically by a lymphoplasmacytic infiltrate, with or without a pancreatic mass. Type 1 AIP is the pancreatic manifestation of an IgG4-related systemic disease and is characterized by elevated IgG4 serum levels, infiltration of IgG4-positive plasma cells and extrapancreatic lesions. Type 2 AIP usually has none or very few IgG4-positive plasma cells, no serum IgG4 elevation and appears to be a pancreas-specific disorder without extrapancreatic involvement. AIP is diagnosed in approximately 2%-6% of patients that undergo pancreatic resection for suspected pancreatic cancer. There are three patterns of autoimmune pancreatitis: diffuse disease is the most common type, with a diffuse, “sausage-like” pancreatic enlargement with sharp margins and loss of the lobular contours; focal disease is less common and manifests as a focal mass, often within the pancreatic head, mimicking a pancreatic malignancy. Multifocal involvement can also occur. In this paper we describe the features of AIP at ultrasonography, computed tomography, magnetic resonance and positron emission tomography/computed tomography imaging, focusing on diagnosis and differential diagnosis with pancreatic ductal adenocarcinoma. It is of utmost importance to make an early correct differential diagnosis between these two diseases in order to identify the optimal therapeutic strategy and to avoid unnecessary laparotomy or pancreatic resection in AIP patients. Non-invasive imaging plays also an important role in therapy monitoring, in follow-up and in early identification of disease recurrence.

Autoimmune pancreatitis in the context of IgG4-related disease: Review of imaging findings

Current understanding of autoimmune pancreatitis (AIP) recognizes a histopathological subtype of the disease to fall within the spectrum of IgG4-related disease. Along with clinical, laboratory, and histopathological data, imaging plays an important role in the diagnosis and management of AIP, and more broadly, within the spectrum of IgG4-related disease. In addition to the defined role of imaging in consensus diagnostic protocols, an array of imaging modalities can provide complementary data to address specific clinical concerns. These include contrast-enhanced computed tomography (CT) and magnetic resonance (MR) imaging for pancreatic parenchymal lesion localization and characterization, endoscopic retrograde and magnetic resonance cholangiopancreatography (ERCP and MRCP) to assess for duct involvement, and more recently, positron emission tomography (PET) imaging to assess for extra-pancreatic sites of involvement. While the imaging appearance of AIP varies widely, certain imaging features are more likely to represent AIP than alternate diagnoses, such as pancreatic cancer. While nonspecific, imaging findings which favor a diagnosis of AIP rather than pancreatic cancer include: delayed enhancement of affected pancreas, mild dilatation of the main pancreatic duct over a long segment, the “capsule” and “penetrating duct” signs, and responsiveness to corticosteroid therapy. Systemic, extra-pancreatic sites of involvement are also often seen in AIP and IgG4-related disease, and typically respond to corticosteroid therapy. Imaging by CT, MR, and PET also play a role in the diagnosis and monitoring after treatment of involved sites.

Autoimmune pancreatitis: updated concepts of a challenging diagnosis

Autoimmune pancreatitis is a benign process characterized by inflammation and fibrosis. It is now known that cases of "autoimmune pancreatitis" actually consist of two distinct pathologic entities. Type 1 autoimmune pancreatitis is a manifestation of a systemic process, immunoglobulin G subclass 4 (IgG4)-related disease. IgG4-related disease can affect virtually every organ system in the body. Type 1 affects older patients and is characterized by an elevated serum IgG4 level and sites of extrapancreatic disease. Type 2 autoimmune pancreatitis is a disease process confined to the pancreas. It affects younger patients and is associated with inflammatory bowel disease. Type 2 is not associated with elevated IgG4 levels or extrapancreatic disease. Both subtypes can mimic malignancy, particularly pancreatic cancer. Awareness of the clinical and imaging features of the subtypes of autoimmune pancreatitis is important to avoid an incorrect diagnosis of malignancy.

Review of the diagnosis, classification and management of autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis, with as yet undetermined incidence and prevalence in the general population. Our understanding of it continues to evolve. In the last few years, 2 separate subtypes have been identified: type 1 AIP has been recognised as the pancreatic manifestation of a multiorgan disease, named immunoglobulin G4 (IgG4)-related disease while type 2 AIP is a pancreas specific disorder not associated with IgG4. International criteria for the diagnosis of AIP have been defined: the HISORt criteria from the Mayo clinic, the Japan consensus criteria and, most recently, the international association of pancreatology “International Consensus Diagnostic Criteria”. Despite this, in clinical practice it can still be very difficult to confirm the diagnosis and differentiate AIP from a pancreatic cancer. There are no large studies into the long-term prognosis and management of relapses of AIP, and there is even less information at present regarding the Type 2 AIP subtype. Further studies are necessary to clarify the pathogenesis, treatment and long-term outcomes of this disease. Critically for clinicians, making the correct diagnosis and differentiating the disease from pancreatic cancer is of the utmost importance and the greatest challenge.

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.

MR imaging of the pancreas

Magnetic resonance (MR) imaging of the pancreas is useful as both a problem-solving tool and an initial imaging examination of choice. With newer imaging sequences such as diffusion-weighted imaging, MR offers improved ability to detect and characterize lesions and identify and stage tumors and inflammation. MR cholangiopancreatography can be used to visualize the pancreatic and biliary ductal system. In this article, the use of MR to evaluate the pancreas, including recent advances, is reviewed and the normal appearance of the pancreas on different imaging sequences, as well as inflammatory diseases, congenital abnormalities, and neoplasms of the pancreas, are discussed.

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.

Imaging biliary strictures--a pictorial review

The diagnosis of biliary diseases may be delayed or missed because of an unpredictable clinical course and presentation. Some biliary diseases carry the risk of morbidity and mortality and are difficult to treat. The purpose of this article is to revisit the various causes and the appearances of biliary strictures on different imaging modalities and to emphasize the role of magnetic resonance imaging (MRI) with magnetic resonance cholangiopancreatography (MRCP) in their evaluation compared with endoscopic retrograde cholangiopancreatography. MRI with MRCP is advantageous to endoscopic retrograde cholangiopancreatography for being a 1-stop shop to provide biliary, soft tissue, and vascular information that is helpful for planning intervention or surgery. Thus it serves as a superb imaging modality for the evaluation of biliary strictures.

Clinics in diagnostic imaging. 145

A 63-year-old man presented with painless jaundice, loss of appetite and significant weight loss. Cross-sectional imaging showed a diffusely enlarged pancreas, with no significant fat stranding and a hypodense rim on computed tomography, which appeared hypointense on T2-weighted magnetic resonance imaging. There was a narrowed pancreatic duct and features of common bile duct narrowing in the region of the pancreatic head. However, there was no obvious mass seen in the pancreatic head region. These features were classical of autoimmune pancreatitis with diffuse involvement of the gland. Laboratory investigation showed abnormal liver function and the classical sign of raised immunoglobulin G class 4 antibodies. The patient showed dramatic response to high-dose steroids, with resolution of both the laboratory and imaging abnormalities within one month. We discuss the classical imaging features of Type 1 autoimmune pancreatitis, an uncommon condition that needs to be differentiated from pancreatic malignancy.

Ultrasonographic findings of extrapancreatic lesions associated with autoimmune pancreatitis

AIM: To summarize ultrasononographic findings of extrapancreatic lesions associated with autoimmune pancreatitis (AIP).

METHODS: Sixteen patients with AIP underwent ultrasound examination of the pancreatic duct, bile duct, gall bladder, peripancreatic lymph nodes, kidneys, parotid glands, submandibular glands, and lacrimal glands to observe whether the pancreatic duct and bile duct were dilated, the gall bladder wall was thickened, parapancreatic lymph nodes were enlarged, echoes of the kidneys were evenly distributed, and the parotid glands, submandibular glands and lacrimal glands mimicked symptoms associated with Sjogren's syndrome.

RESULTS: Of 16 patients, 6 had dilated pancreatic ducts, 8 had dilated bile ducts, 6 had thickening of the gall bladder wall, and 3 had enlarged peripancreatic lymph nodes. Of 10 patients who underwent examination of the parotid glands, submandibular glands, and lacrimal glands, one had abnormalities in the parotid glands, 3 in the submandibular glands, and 7 in the lacrimal glands.

CONCLUSION: Lacrimal gland abnormalities occur more usually in AIP patients, which may be useful for the differentiation of AIP from pancreatic cancer.

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.

Differential diagnosis of sclerosing cholangitis with autoimmune pancreatitis and periductal infiltrating cancer in the common bile duct at dynamic CT, endoscopic retrograde cholangiography and MR cholangiography

OBJECTIVES

To compare findings at dynamic computed tomography (CT), endoscopic retrograde cholangiography (ERC) and magnetic resonance cholangiography (MRC) in patients with sclerosing cholangitis with autoimmune pancreatitis (SC-AIP) and periductal infiltrating cancer in the common bile duct (CBD), and to evaluate the diagnostic performance of ERC and MRC in differentiating between the two diseases.

METHODS

Bile duct changes at dynamic CT, ERC and MRC were compared in 58 patients with SC-AIP and CBD involvement and 93 patients with periductal infiltrating CBD cancer. Two radiologists rated their confidence in differentiating between the two diseases and the diagnostic performances of ERC and MRC were compared.

RESULTS

At CT, SC-AIP was more frequently associated with intrapancreatic CBD involvement, thinner CBD walls, concentric wall thickening, smooth outer margins, and lower degrees of upstream ductal dilatation and contrast enhancement (P ≤ 0.05) than CBD cancer. At ERC and MRC, SC-AIP was more frequently associated with smooth margins, gradual and symmetric narrowing, multifocal involvement and hourglass appearance (P ≤ 0.027) than CBD cancer. MRC showed good diagnostic performance comparable to ERC.

CONCLUSIONS

Dynamic CT, ERC and MRC can be helpful in distinguishing SC-AIP from periductal infiltrating CBD cancer. MRC may be a useful diagnostic alternative to ERC in differentiating between the two diseases.

KEY POINTS

• SC-AIP often mimics periductal infiltrating ductal cancer. • Imaging findings of SC-AIP and periductal infiltrating CBD cancer can be similar. • Dynamic CT, ERC and MRC help differentiate between these two diseases. • MRC may be a useful diagnostic alternative to ERC.

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.

Clinical analysis of 36 cases of autoimmune pancreatitis in China

BACKGROUND

To improve the early identification of autoimmune pancreatitis in China by a retrospective analysis of clinical data from AIP patients.

METHODOLOGY/PRINCIPAL FINDINGS

The analysis included 36 patients admitted by the surgery department of our hospital from January 2003 to October 2011 whose postoperative pathological confirmations were consistent with the histological criteria of Honolulu Consensus Document. The clinical phenotypes associated with the histopathologic patterns of LPSP and IDCP were referred to as type 1 and type 2 of AIP, respectively. A retrospective analysis of clinical features, serological data, pathological findings and imageological records was performed in line with the subtypes of AIP. Type 1 showing a sex predilection (males) was commonly more dominant than type 2 in all AIP. Type 2 without a gender predilection was, on average, a decade younger than type 1. Type 1 was inferior to type 2 in ALT, ALP and γ-GT with statistical significance (P = 0.044, 0.025 and 0.013). Type 1 was inferior to type 2 in AST with difference close to statistical significance (P = 0.072). Histopathology revealed frequent lymphoplasmacytic infiltration with less frequent infiltration of neutrophils, eosinophils and fibroblasts. Diffuse and intensive interstitial fibrosis could be seen. The changes of pancreatic head were more frequently seen in type 2 than in type 1 (P = 0.05). Plasma cells staining of IgG4 at a density of over 30 or more cells per high-power field appeared to be a specific finding in China with type 1. Imageology found a diffusely or focally enlarged pancreas, most frequently a mass or enlargement in the pancreatic head, characteristic capsule-like rim, calcification or pancreatic calculus and cystic degeneration.

CONCLUSIONS/SIGNIFICANCE

AIP is a unique type of chronic pancreatitis and has distinctive serological, pathological and imageological characteristics, which should be used for differentiation from pancreatic cancer.

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.

Immunological diseases of the pancreatico-hepatobiliary system: update on etiopathogenesis and cross-sectional imaging findings

Immunological diseases of the hepatobiliary system and the pancreas include a broad spectrum of disorders that manifest characteristic histopathology/serology and variable clinical features and imaging findings. Recent studies have thrown fresh light on the complex role of genetics and autoimmunity in the pathogenesis and natural history of these diverse disorders that include autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis, IgG4-related cholangitis, overlap/outlier syndromes, and autoimmune pancreatitis.