Autoimmune pancreatitis: CT and MR characteristics

Japanese consensus guidelines for management of autoimmune pancreatitis: I. Concept and diagnosis of autoimmune pancreatitis

As the number of patients with autoimmune pancreatitis (AIP) is increasing in Japan, practical guidelines for managing AIP need to be established. Three committees [the professional committee for developing clinical questions (CQs) and statements by Japanese specialists, the expert panelist committee for rating statements by the modified Delphi method, and the evaluating committee of moderators] were organized. Fifteen AIP specialists extracted specific clinical statements from a total of 871 articles in the literature using a PubMed search (1963-2008) and a secondary database, and developed the CQs and statements. The expert panelists individually rated these clinical statements using a modified Delphi approach in which a clinical statement receiving a median score greater than 7 on a 9-point scale from the panel was regarded as valid. The professional committee developed 13, 6, 6, and 11 CQs and statements for the concept and diagnosis, extra-pancreatic lesions, differential diagnosis and treatment, respectively. The expert panelists regarded them as valid after two-round modified Delphi approaches.After evaluation by the moderators, the Japanese clinical guidelines for AIP were established. The digest versions of the present guidelines have been published in the official journal of the Japan Pancreas Society, "Pancreas." Full versions divided into three series are scheduled to be published in the present and followings two issues in the Journal of Gastroenterology with approval of Professor Go VLW, the Editor-in-Chief of "Pancreas."

Autoimmune pancreatitis: a challenging diagnostic puzzle for clinicians

Autoimmune pancreatitis is a form of pancreatitis with autoimmune stigmata that may present as either focal or diffuse gland involvement. In focal forms, autoimmune pancreatitis shares demographic, clinical, biochemical and imaging features with pancreatic cancer. Since autoimmune pancreatitis is a benign disease and steroid therapy can rapidly resolve symptoms, improve radiological findings and avoid unnecessary surgery, the current clinical challenge is how to differentiate autoimmune pancreatitis from pancreatic neoplasia. Even though definitive diagnosis of the disease is difficult, several diagnostic criteria have been proposed and progress has been made in imaging studies. The management of this unique form of pancreatitis should, therefore, be handled in centres with knowledge of all aspects of the disease. This article briefly reviews clinical aspects of autoimmune pancreatitis with a focus on its diagnostic imaging and management.

Incidence and characteristics of chronic and lymphoplasmacytic sclerosing pancreatitis in patients scheduled to undergo a pancreatoduodenectomy

BACKGROUND

The determination of the exact nature of a pancreatic head mass in a patient scheduled to undergo a pancreatoduodenectomy can be very difficult. This is important as patients who suffer from benign disease such as pancreatitis do not always require surgery. The aim of the present study was to analyse the incidence of pancreatitis and the signs and symptoms associated with these tumours mistaken for pancreatic cancer and the diagnostic procedures performed.

METHODS

A consecutive group of patients who underwent a pancreatoduodenectomy between 1992 and 2005 with histopathologically proven pancreatic adenocarcinoma (PCA) and pancreatitis were analysed.

RESULTS

The incidence of pancreatitis after pancreatoduodenectomy is 63 out of 639 patients who underwent a pancreaticoduodenectomy (9.9%). Of these patients, 24 patients (38%) had lymphoplasmacytic sclerosing pancreatitis (LPSP) and 31 patients (49%) had focal chronic pancreatitis. Eight patients (13%) had an intermediate form with characteristics of both. Pancreatic adenocarcinoma occurred in 227 patients (36%). The presence of pancreatitis without a discrete mass on endoscopic ultrasonography (EUS) seemed to have clinical relevance with a positive likelihood ratio of 5.1. Mortality after resection was nil in both groups.

CONCLUSION

The incidence of pancreatitis is 9.9% for patients scheduled to undergo a pancreatoduodenectomy. Of these patients, 38% had LPSP, 13% had a intermediate form and 49% had focal chronic pancreatitis. The determination of the exact nature of a pancreatic head mass remains difficult.

Japanese clinical guidelines for autoimmune pancreatitis

OBJECTIVES

As the patients with autoimmune pancreatitis (AIP) are increasing in Japan, the practical guideline for managing AIP is required to be established.

METHODS

Three committees (the professional committee for making clinical questions [CQs] and statements by Japanese specialists, the expert panelist committee for rating statements by the modified Delphi method, and the evaluating committee by moderators) were organized. Fifteen specialists for AIP extracted the specific clinical statements from a total of 871 literatures by PubMed search (approximately 1963-2008) and from a secondary database and made the CQs and statements. The expert panelists individually rated these clinical statements using a modified Delphi approach, in which a clinical statement receiving a median score greater than 7 on a 9-point scale from the panel was regarded as valid.

RESULTS

The professional committee made 13, 6, 6, and 11 CQs and statements for the concept and diagnosis, extrapancreatic lesions, differential diagnosis, and treatment, respectively. The expert panelists regarded them as valid after a 2-round modified Delphi approach.

CONCLUSIONS

After evaluation by the moderators, the Japanese clinical guideline for AIP has been established. Further studies for the international guideline are needed after international consensus for diagnosis and treatment.

Autoimmune pancreatitis: imaging findings on contrast-enhanced MR, MRCP and dynamic secretin-enhanced MRCP

PURPOSE

This study retrospectively determined magnetic resonance (MR), MR cholangiopancreatography (MRCP) and secretin-MRCP findings in patients with autoimmune pancreatitis (AIP).

MATERIALS AND METHODS

The MR examinations of 28 patients with histopathologically proven AIP were reviewed. In 14 cases, secretin-enhanced MRCP was performed. The observers evaluated pancreatic parenchymal enlargement, signal intensity abnormalities, enhancement, vascular involvement, bile-duct diameter and main pancreatic duct (MPD) narrowing (diffuse/focal/segmental). After secretin administration, the presence of the "duct-penetrating" sign was evaluated.

RESULTS

MR imaging showed diffuse pancreatic enlargement in 8/28(29%) cases, focal pancreatic enlargement in 16/28 (57%) cases and no enlargement in 4/28 (14%) cases. The alteration of pancreatic signal intensity was diffuse in 8/28 (29%) cases (eight diffuse AIP) and focal in 20/28 (71%) cases (20 focal AIP). Delayed pancreatic enhancement was present in all AIP, with peripheral rim of enhancement in 8/28 (29%) AIP (1/8 diffuse, 7/20 focal); vascular encasement was present in 7/28 (25%) AIP (1/8 diffuse, 6/20 focal); distal common bile duct narrowing was present in 12/28(43%) AIP (5/8 diffuse, 7/20 focal). MRCP showed MPD narrowing in 17/28 (61%) AIP (4/8 diffuse, 15/20 focal), MPD dilation in 8/28(29%) AIP (3/8 diffuse, 5/20 focal) and normal MPD in 1/8 diffuse AIP. Secretin-MRCP showed the duct-penetrating sign in 6/14(43%) AIP (one diffuse AIP with MPD segmental narrowing, five focal AIP with MPD focal narrowing), demonstrating integrity of the MPD.

CONCLUSIONS

Delayed enhancement and MPD stenosis are suggestive for AIP on MR and MRCP imaging. Secretin-enhanced MRCP is a problem-solving tool in the differential diagnosis between focal AIP and ductal adenocarcinoma.

Autoimmune pancreatitis: differentiation from pancreatic carcinoma and normal pancreas on the basis of enhancement characteristics at dual-phase CT

OBJECTIVE

The purposes of this study were to define the pancreatic enhancement of autoimmune pancreatitis at dual-phase CT and to compare it with that of pancreatic carcinoma and a normal pancreas.

MATERIALS AND METHODS

Dual-phase CT scans of 101 patients (43 with autoimmune pancreatitis, 13 cases of which were focal; 33 with pancreatic carcinoma, and 25 with a normal pancreas) were evaluated. One radiologist measured the CT attenuation of the pancreatic parenchyma and pancreatic masses in both the pancreatic and hepatic phases of imaging. The mean CT attenuation value of the pancreatic parenchyma in patients with autoimmune pancreatitis was compared with that in patients with a normal pancreas. The mean CT attenuation value of the focal masses in the focal form of autoimmune pancreatitis was compared with that of carcinomas.

RESULTS

In the pancreatic phase, the mean CT attenuation value of the pancreatic parenchyma in patients with autoimmune pancreatitis was significantly lower than that in patients with a normal pancreas (autoimmune pancreatitis, 85 HU; normal pancreas, 104 HU; p < 0.05). In the hepatic phase, however, the mean CT attenuation values were not significantly different (autoimmune pancreatitis, 96 HU; normal pancreas, 89 HU; p = 0.6). In the pancreatic phase, the mean CT attenuation value of the mass in autoimmune pancreatitis was not significantly different from that of carcinoma (autoimmune pancreatitis, 71 HU; carcinoma, 59 HU; p = 0.06), but in the hepatic phase, the value was significantly higher than that of carcinoma (autoimmune pancreatitis, 90 HU; carcinoma, 64 HU; p < 0.001).

CONCLUSION

At dual-phase CT, the enhancement patterns of the pancreas and pancreatic masses in patients with autoimmune pancreatitis are different from those of pancreatic carcinoma and normal pancreas.

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.

Long-term outcome of autoimmune pancreatitis

PURPOSE

Autoimmune pancreatitis (AIP) is a unique form of pancreatitis and can be complicated with various extrapancreatic lesions. Little is known about the long-term clinical course of AIP. Here we aimed to document the clinical course of AIP.

METHODS

For this study, we recruited 21 patients, averaging 66.5 years in age (range, 19-84 years) and observed them at a mean interval of 40.8 months (range, 18-130 months). Three of the patients were also diagnosed with retroperitoneal fibrosis, 3 had sialoadenitis, 2 had chronic thyroiditis, 1 had interstitial nephritis, and 1 had interstitial pneumonia. Three of the patients underwent surgical therapy, 12 patients received methylprednisolone (PSL) treatment, and the 6 remaining patients received no treatment.

RESULTS

Enlargement of the pancreas was attenuated in all the PSL-treated patients. Seven of the 21 patients showed pancreatic atrophy, of whom 2 were non-PSL-treated patients. Three patients developed chronic pancreatitis. One patient was diagnosed with pancreatic cancer after 50 months of PSL therapy.

CONCLUSIONS

As with chronic pancreatitis patients, AIP patients should be observed closely for abnormality in pancreatic function.

Usefulness of positron emission tomography in the evaluation of distribution and activity of systemic lesions associated with autoimmune pancreatitis

BACKGROUND/AIMS

Autoimmune pancreatitis (AIP) is an IgG4-related systemic disease often accompanied with a variety of lesions outside of the pancreas and is treated with steroid therapy. The aim of this study is to analyze the usefulness of positron emission tomography with (18)F-fluorodeoxyglucose (FDG-PET) in the evaluation of distribution and activity of systemic lesions of AIP during steroid therapy.

METHODS

Eleven cases of AIP had their FDG-PET images evaluated before and 3 months after steroid therapy and another 2 cases only before therapy. AIP activity was determined by the level of serum markers, IgG and IgG4, and compared with findings of PET.

RESULTS

In all 13 cases of AIP, a moderate to intense level of FDG accumulation was recognized in the pancreatic lesion before steroid therapy. Of 13 patients, 11 (84.6%) showed FDG accumulation in the multiple organs, such as mediastinal and other lymph nodes, salivary gland, biliary tract, prostate, and aortic wall. In 11 patients who underwent PET before and after steroid therapy, FDG accumulation was diminished in almost all systemic lesions, with a mean of maximum standardized uptake value (SUV(max)) in the pancreatic lesion from 5.12 to 2.69. Similar to the SUV level, serum IgG and IgG4 were decreased in most of the cases after steroid therapy.

CONCLUSIONS

FDG-PET is an effective modality to evaluate the response of steroid therapy and the distribution and activity of various systemic lesions of AIP.

Autoimmune pancreatitis in Japan: overview and perspective

Since the rediscovery and definition of autoimmune pancreatitis (AIP) by Yoshida et al. in 1995, the disease has been attracting attention because of its unique clinical features and practical issues. This disease shows very impressive imaging findings, serological changes, and characteristic histopathology. It occurs most commonly in elderly males with painless jaundice or mild abdominal pain; resemblance in imaging findings between AIP and pancreatobiliary cancers poses an important practical issue of differentiation. With increasing recognition of AIP and accumulation of cases, another important feature of this disease has been revealed, i.e., association of extrapancreatic organ involvements. Initially misunderstood because it can be accompanied by other autoimmune disorders, such as Sjögren's syndrome or primary sclerosing cholangitis (PSC), AIP is now known to be associated with unique types of sialadenitis and cholangitis distinct from Sjögren's syndrome or PSC. Now the concept of "IgG4-related sclerosing disease" has become widely accepted and the list of organs involved continues to increase. With worldwide recognition, an emerging issue is the clinical definition of other possible types of autoimmune-related pancreatitis called "idiopathic duct-centric chronic pancreatitis (IDCP)" and "AIP with granulocyte epithelial lesion (GEL)" and their relation to AIP with lymphoplasmacytic sclerosing pancreatitis (LPSP). The time has arrived to establish clinical diagnostic criteria of AIP based on international consensus and to discuss regional and racial differences in the clinicopathological features of AIP. Consensus guidelines are also required for the ideal use of steroids in the treatment of AIP to suppress recurrence efficiently with minimal side effects. There are many issues to be settled in AIP; international collaboration of experts in the pancreas field is necessary to clarify the entire picture of this unique and important disease.

[From the chronic pancreatitis to chronic pancreatites]

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

Possible association between IgG4-associated systemic disease with or without autoimmune pancreatitis and non-Hodgkin lymphoma

OBJECTIVES

IgG4-associated systemic disease (ISD) is a multiorgan fibroinflammatory disorder whose pancreatic manifestation is called autoimmune pancreatitis (AIP). We describe 3 patients who developed non-Hodgkin lymphoma during the follow-up of ISD.

METHODS

At our institution's pancreas clinic, we have prospectively and retrospectively examined patients with ISD with (n = 101) or without (n = 10) AIP (mean age, 59 years; 90 males and 21 females). We reviewed the medical records of all 111 patients to identify patients who developed non-Hodgkin lymphoma during the follow-up since their first presentation of ISD. Standardized incidence rate was calculated.

RESULTS

The 111 patients with ISD with or without AIP had 331 patient-years of observation during which 3 patients had a diagnosis of non-Hodgkin lymphoma 3 to 5 years after the diagnosis of ISD. In these patients who later developed lymphoma, ISD involved the pancreas (AIP) in 2 and salivary gland in 1. Non-Hodgkin lymphoma had extranodal involvement in all patients (liver [n = 2], adrenal glands [n=1], kidney [n= 1], and lung [n = 1]). Standardized incidence rate was 16.0 (95% confidence interval, 3.3-45.5).

CONCLUSIONS

We report 3 cases of non-Hodgkin lymphoma that developed during the follow-up of ISD suggesting that patients with ISD may be at an increased risk of developing non-Hodgkin lymphoma.

[Autoimmune pancreatitis]

Autoimmune pancreatitis has been established as a special entity of pancreatitis. It is an enigmatic disease since it is adding an autoimmune etiology to the existing causes of pancreatitis. Morphological hallmarks of the disease are narrowing of the pancreatic duct system and the bile duct by periductal lymphoplasmocytic inflammation. This results in many cases in obstructive jaundice due to a mass-forming lesion in the pancreatic head mimicking pancreatic ductal adenocarcinoma. Therefore, patients will frequently undergo surgery. Histopathologically, the disease can be diagnosed by IgG4-positive plasma cells. Serologically, patients may present with elevated serum IgG and IgG4 levels. Other autoantibodies are also described. Association with other autoimmune manifestations in a wide range of organs is frequent. Autoimmune pancreatitis will respond to steroid treatment, which is of specific importance because pancreatic cancer is one of its clinical differential diagnoses. It is important to positively diagnose autoimmune pancreatitis, especially if the bile ducts are affected, since cholangitis may be or become a prominent problem before or after surgery.

Autoimmune pancreatitis: an update

Autoimmune pancreatitis (AIP) is the pancreatic manifestation of a systemic fibroinflammatory disorder. It has been recognized as a distinct clinical entity, only recently. Multiple organs, such bile ducts, salivary glands, kidneys and lymph nodes, can be involved either synchronously or metachronously. It is one of the few autoimmune conditions that predominantly affects male subjects in the fifth and sixth decades of life. Obstructive jaundice is the most common presenting symptom but the presentation can be quite nonspecific. There are established diagnostic criteria to diagnose AIP, most of which rely on a combination of clinical presentation, imaging of the pancreas and other organs (by CT scan, MRI and endoscopic retrograde pancreatography), serology, pancreatic histology and response to steroids to make the diagnosis. It is imperative to differentiate AIP from pancreatic cancer owing to the vastly different prognostic and therapeutic implications. AIP responds dramatically to steroid treatment but relapses are common. Relapse of AIP can often be retreated with steroids. As the collective experience with this condition increases, a better understanding of the natural history of this disease is emerging.

Autoimmune pancreatitis: pancreatic and extrapancreatic imaging findings

OBJECTIVE

The purpose of this article is to discuss the systemic nature of autoimmune pancreatitis and its various pancreatic and extrapancreatic imaging findings.

CONCLUSION

Autoimmune pancreatitis is a systemic disease with a wide range of pancreatic and extrapancreatic imaging findings. These findings can mimic those of other diseases in the pancreas or other organs and therefore are commonly misdiagnosed and mistreated. It is important for radiologists to understand both the pancreatic and extrapancreatic imaging findings of autoimmune pancreatitis to make accurate and timely diagnoses.

Magnetic resonance imaging in pancreatitis

Pancreatitis can occur in acute and chronic forms. Magnetic resonance imaging (MRI) plays an important role in the early diagnosis of both conditions and complications that may arise from acute or chronic inflammation of the gland. Standard MRI techniques including T1-weighted and T2-weighted fat-suppressed imaging sequences together with contrast-enhanced imaging can both aid in the diagnosis of acute pancreatitis and demonstrate complications as pseudocysts, hemorrhage, and necrosis. Combined use of MRI and MR cholangiopancreatography can show both parenchymal findings that are associated with chronic pancreatitis including pancreatic size and signal and arterial enhancements, all of which are diminished in chronic pancreatitis. The degree of main pancreatic duct dilatation and/or the number of side branch ectasia determines the diagnosis of chronic pancreatitis and its severity. In this paper, we report the spectrum of imaging findings of acute and chronic pancreatitis on MRI and MR cholangiopancreatography.

Autoimmune pancreatitis and IgG4-associated sclerosing cholangitis

Autoimmune pancreatitis (AIP) is a unique form of chronic pancreatitis characterised by a high serum IgG4 concentration and complications that include various extrapancreatic manifestations, one of which is sclerosing cholangitis. In AIP patients, infiltration of abundant IgG4-positive plasma cells and dense fibrosis are commonly observed in the pancreas and wall of the bile duct and gallbladder. The major symptom at onset of AIP is obstructive jaundice caused by stricture of the bile duct, and this requires differential diagnosis of AIP from pancreato-biliary malignancies and primary sclerosing cholangitis (PSC). Recently, there have been reports of particular cases of sclerosing cholangitis with a high serum IgG4 level and cholangiographic and pathological findings comparable to those observed in AIP patients. Being apparently different from PSC and similar to that in AIP, sclerosing cholangitis with and without AIP shows a clinical response to steroid therapy and thus is designated as 'IgG4-associated sclerosing cholangitis'. The pathogenesis of AIP and IgG4-associated sclerosing cholangitis remains at yet undetermined.

Usefulness of serum IgG4 in the diagnosis and follow up of autoimmune pancreatitis: A systematic literature review and meta-analysis

High circulating serum immunoglobulin G4 (IgG4) levels have been proposed as a marker of autoimmune pancreatitis (AIP). The aim of the present study was to review the data existing in the English literature on the usefulness of the IgG4 serum levels in the diagnosis and follow up of patients with AIP. A total of 159 patients with AIP and 1099 controls were described in seven selected papers reporting the usefulness of serum IgG4 in diagnosing AIP. In total, 304 controls had pancreatic cancer, 96 had autoimmune diseases, and the remaining 699 had other conditions. The summary receiver-operating characteristic curve analysis was carried out by means of Meta-DiSc open-access software. Serum IgG4 showed good accuracy in distinguishing between AIP and the overall controls, pancreatic cancer and other autoimmune diseases (area under the curve [+/- SE]: 0.920 +/- 0.073, 0.914 +/- 0.191, and 0.949 +/- 0.024, respectively). The studies analyzed showed significantly heterogeneous specificity values in each of the three analyses performed. The analysis of the four studies comparing AIP and pancreatic cancers also showed significantly heterogeneous values of sensitivities and odds ratios. Regarding the usefulness of IgG4 as a marker of efficacy of steroid treatment, a decrease in the serum concentrations of IgG4 was found in the four available studies. The serum IgG4 subclass is a good marker of AIP, and its determination should be included in the diagnostic workup of this disease. However, the heterogeneity of the studies published until now means that more studies are necessary in order to better evaluate the true accuracy of IgG4 in discriminating AIP versus other autoimmune diseases.

Autoimmune pancreatitis: disease evolution, staging, response assessment, and CT features that predict response to corticosteroid therapy

PURPOSE

To evaluate the evolution of morphologic features of autoimmune pancreatitis (AIP) at computed tomography (CT) and to identify imaging features that can predict AIP response to corticosteroid therapy (CST).

MATERIALS AND METHODS

This HIPAA-compliant retrospective study had institutional review board approval. From among a cohort of 63 patients with AIP, 15 patients (12 men, three women; mean age, 64.7 years; age range, 30-84 years) who underwent sequential CT examinations before treatment were included to assess the evolution of disease by reviewing pancreatic, peripancreatic, and ductal changes. Of these patients, 13 received CST and underwent posttreatment CT; these CT studies were evaluated to determine if there were imaging features that could predict response to CST.

RESULTS

The disease evolved from changes of diffuse (14 of 15 patients) or focal (one of 15 patients) parenchymal swelling, peripancreatic stranding (10 of 15 patients), "halo" (nine of 15 patients), pancreatic duct changes (15 of 15 patients), and distal common bile duct narrowing (12 of 15 patients) to either resolution or development of ductal strictures and/or focal masslike swelling. In 13 patients treated with CST, favorable response to treatment was seen in those with diffuse pancreatic and peripancreatic changes. Suboptimal response was seen in patients with ductal stricture formation (two of 13 patients) and in those in whom focal masslike swellings persisted after resolution of diffuse changes (seven of 13 patients).

CONCLUSION

CT features like diffuse swelling and halo respond favorably to CST and likely reflect an early inflammatory phase, whereas features like ductal strictures and focal masslike swelling are predictive of a suboptimal response and symbolize a late stage with predominance of fibrosis.

Asian diagnostic criteria for autoimmune pancreatitis: consensus of the Japan-Korea Symposium on Autoimmune Pancreatitis

In 2002, the Japan Pancreas Society (JPS) was the first in the world to propose diagnostic criteria for autoimmune pancreatitis (AIP). Since the concept of AIP has changed with the accumulation of AIP cases, the Research Committee of Intractable Pancreatic Diseases (RCIPD) provided by the Ministry of Health, Labour and Welfare of Japan and the JPS issued revised clinical diagnostic criteria of AIP in 2006. The Asan Medical Center of Korea also proposed diagnostic criteria for AIP in 2006. However, there are subtle but clinically challenging differences between the Japanese and Korean criteria. This inconsistency makes it difficult to compare data in studies from different centers and elucidate the characteristics of AIP. To reach a consensus on AIP, the RCIPD and the Korean Society of Pancreatobiliary Diseases established the following Asian criteria for the diagnosis of AIP: I-1. Imaging studies of pancreatic parenchyma show a diffuse/segmental/focally enlarged gland, occasionally with a mass and/or a hypoattenuation rim. I-2. Imaging studies of pancreaticobiliary ducts show diffuse/segmental/focal pancreatic ductal narrowing, often with stenosis of the bile duct. (Both I-1 and I-2 are required for diagnosis). II. Elevated level of serum IgG or IgG4, and detection of autoantibodies. III. Common lymphoplasmacytic infiltration and fibrosis, with abundant IgG4-positive cell infiltration. AIP should be diagnosed when criterion I and one of the other two criteria are satisfied, or when histology shows the presence of lymphoplasmacytic sclerosing pancreatitis in the resected pancreas. A diagnostic trial of steroid therapy can be applied carefully by expert pancreatologists only in patients fulfilling criterion I alone with negative diagnostic work-up results for pancreatobiliary cancer.

Strategy for differentiating autoimmune pancreatitis from pancreatic cancer

OBJECTIVES

It is of utmost importance that autoimmune pancreatitis (AIP) be differentiated from pancreatic cancer (PC) because some AIP cases undergo unnecessary laparotomy or pancreatic resection on suspicion of PC. This study aimed to develop an appropriate strategy for differentiating between AIP and PC.

METHODS

Clinical, serological, and radiological features of 17 AIP patients forming a masslike lesion on pancreas head and 70 patients with pancreatic head cancer were compared.

RESULTS

Numerous findings can be used to distinguish between AIP and PC, and the following are more likely in AIP: fluctuating jaundice; elevated serum IgG4 levels; delayed enhancement of the enlarged pancreas and a capsule-like low-density rim on computed tomography; long or skipped narrowed portion with side branches of the main pancreatic duct without upstream dilatation on endoscopic retrograde pancreatography, extrapancreatic lesions, such as stenosis of the intrahepatic bile duct, salivary gland swelling, and retroperitoneal mass; and responsiveness to steroid therapy.

CONCLUSIONS

In elderly male patients presenting with obstructive jaundice and a pancreatic mass, AIP should be considered in the differential diagnosis. Based on a combination of clinical, serological, and radiological findings, AIP can be differentiated from PC. An algorithm for management of patients with a masslike lesion on pancreas head is presented.

Renal cortical lesions in patients with autoimmune pancreatitis: A clue to differentiation from pancreatic malignancy

AIM

To describe the occurrence of renal cortical lesions (RCLs) in patients with autoimmune pancreatitis (AIP).

METHODS

This retrospective study was approved by our research ethics board; informed consent was waived. Systematic search of CT scan reports in 5-year interval yielded 17 patients with AIP (male:female; 11:6, age 18-80 years). A consecutive group of 22 patients with pancreatic adenocarcinoma was used as control (male:female; 10:12, age 42-76 years). The CT scans of the two groups were mixed and randomized. Two blinded radiologists independently reviewed the kidneys for the presence of wedge-shaped RCLs. Fisher's exact test was used to determine statistical significance. Consensus review of all imaging of positive patients with AIP and RCLs and three additional patients identified anecdotally was performed.

RESULTS

Both readers independently identified the same 6/17 (35%) patients in the study group and 0/22 in the control group with two or more RCLs. This difference was statistically significant (p=0.004). The sensitivity, specificity, positive and negative predictive values of RCLs in the differentiation of AIP from pancreatic adenocarcinoma were 35%, 100%, 100%, and 67%, respectively. To the six AIP patients with RCLs, we added three more identified anecdotally. In 7/9, >5 RCLs were seen which were wedge-shaped and cortical-based, ranging from <1 to 4cm. Typical pancreatic findings of AIP were noted in all, with the gland affected focally in 5/9 patients.

CONCLUSION

We have shown the presence of multiple renal cortical lesions which occur in approximately 35% of our AIP patient population.

Diffuse pancreatic ductal adenocarcinoma: Characteristic imaging features

PURPOSE

To evaluate imaging findings of diffuse pancreatic ductal adenocarcinoma.

MATERIALS AND METHODS

We included 14 patients (4 men and 10 women; mean age, 64.5 years) with diffuse pancreatic ductal adenocarcinoma on the basis of retrospective radiological review. Two radiologists retrospectively reviewed 14 CT scans in consensus with respect to the following: tumor site, peripheral capsule-like structure, dilatation of intratumoral pancreatic duct, parenchymal atrophy, and ancillary findings. Eight magnetic resonance (MR) examinations with MR cholangiopancreatography (MRCP) and seven endoscopic retrograde cholangiopancreatography (ERCP) were also reviewed, focusing on peripheral capsule-like structure and dilatation of intratumoral pancreatic duct.

RESULTS

CT revealed tumor localization to the body and tail in 11 (79%) patients and peripheral capsule-like structure in 13 (93%). The intratumoral pancreatic duct was not visible in 13 (93%). Pancreatic parenchymal atrophy was not present in all 14 patients. Tumor invasion of vessels was observed in all 14 patients and of neighbor organs in 8 (57%). On contrast-enhanced T1-weighted MR images, peripheral capsule-like structure showed higher signal intensity in five patients (71%). In all 11 patients with MRCP and/or ERCP, the intratumoral pancreatic duct was not dilated.

CONCLUSION

Diffuse pancreatic ductal adenocarcinoma has characteristic imaging findings, including peripheral capsule-like structure, local invasiveness, and absence of both dilatation of intratumoral pancreatic duct and parenchymal atrophy.

Autoimmune pancreatitis: with special reference to a localized variant

In 2006, the Japan Pancreas Society revised the diagnostic criteria for autoimmune pancreatitis (AIP) so as to more clearly define its morphological, pathological, and immunological features, as follows: (1) diffuse or segmental narrowing of the main pancreatic duct with an irregular wall and diffuse or localized enlargement of the pancreas recognized by imaging studies; (2) high serum gamma globulin, IgG, or IgG4 levels, or the presence of autoantibodies; and (3) marked interlobular fibrosis and prominent infiltration of lymphocytes and plasma cells in the periductal area, occasionally with lymphoid follicles in the pancreas. Establishing a diagnosis of AIP has become easier with knowledge of its immunological abnormalities, including serum IgG4 levels. However, the localized form of AIP sometimes mimics pancreatic cancer. The rate of focal mass formation in patients with AIP is reportedly 24%-43%; however, there have been few reports on the histological findings of localized AIP, in contrast to mass-forming pancreatitis (MFP). Our review of patients who had undergone resection due to a preoperative diagnosis of MFP with possible cancer revealed 72% to be patients with localized AIP. For the discrimination of these conditions, it is important to recognize the characteristic ultrasonographic findings of AIP, i.e., (1) diffuse or localized enlargement and hypoechogenicity of the pancreas; (2) rarity of calcification, cystic lesions, and peripancreatic fluid collection; (3) thickened layer structure of the bile duct wall; (4) iso/hypervascularity in the swollen portion of the pancreas; (5) attenuation of pancreatic swelling and bile duct wall thickening after steroid therapy; and (6) multiple hypoechoic masses in various organs, including the pancreas. Contrast-enhanced endoscopic ultrasonography is potentially a useful tool in the differential diagnosis and for assessment of the efficacy of steroid therapy by enabling evaluation of the vascularity of the lesions. Along with the presence of IgG4-positive plasma cells, verification of obliterative phlebitis is highly specific for the histological diagnosis of AIP.

Extrapancreatic F-18 FDG accumulation in autoimmune pancreatitis

We report two cases of autoimmune pancreatitis (AIP) in which fluorine-18 fluorodeoxyglucose (FDG) showed moderate accumulation in the pancreas, as well as in bilateral submandibular glands and in multifocal lymph nodes. FDG positron emission tomography (PET)/computed tomography (CT) is a useful diagnostic tool to assess the extrapancreatic lesions of AIP, which is a recently proposed new clinicopathological entity named immunoglobulin G4 (IgG4)-related systemic disease. Recognition of the FDG-PET/CT findings of IgG4-related sclerosing disease is crucial to avoid unnecessary surgery or other intervention because of similarities to malignant lymphoma or malignant tumor with multiple lymph node metastases.

Autoimmune pancreatitis: a review

Autoimmune pancreatitis has emerged over the last 40 years from a proposed concept to a well established and recognized entity. As an efficient mimicker of pancreatic carcinoma, its early and appropriate recognition are crucial. With mounting understanding of its pathogenesis and natural history, significant advances have been made in the diagnosis of autoimmune pancreatitis. The characteristic laboratory features and imaging seen in autoimmune pancreatitis are reviewed along with some of the proposed diagnostic criteria and treatment algorithms.

Circulating naïve and CD4+CD25high regulatory T cells in patients with autoimmune pancreatitis

OBJECTIVE

Autoimmune pancreatitis (AIP) is a new clinical entity of pancreatic disorder. There are several immunologic and histological abnormalities specific for the disease, including increased levels of serum IgG4 and infiltration of lymphocytes and IgG4-positive plasmacytes. The role of IgG4 is unclear. Recently, regulatory T cells (Tregs) have been reported to be involved in the development of various autoimmune diseases as well as B cell shifting to IgG4-producing plasmacytes. To clarify the role of Tregs in the pathophysiology of AIP, we analyzed circulating Tregs in AIP.

METHODS

We recruited 27 patients with AIP for this study. For comparison, we also recruited 23 patients with other pancreatic disease and 32 healthy subjects as controls. We analyzed Tregs as CD4+CD25high and CD4+CD25+CD45RA+ (naïve) from peripheral blood by flow cytometry.

RESULTS

In peripheral blood, CD4+CD25high Tregs were significantly increased in AIP patients (3.01% T 1.77%) compared with alcoholic chronic pancreatitis (CP) (1.65% T 0.58%), idiopathic CP (1.53% T0.56%), and healthy control (1.72% T 0.81%, P G 0.05). Naïve Tregs significantly decreased in AIP (0.32% T 0.22%) compared with healthy control (0.83% T 0.65%) and CP group (alcoholic and idiopathic CP; 0.52% T 0.40%, P G 0.05). In untreated AIP patients,the number of CD4+CD25high Tregs and IgG4 are correlated (R =0.53, P G 0.05).

CONCLUSIONS

Increased numbers of CD4+CD25high Tregs may influence IgG4 production in AIP, whereas decreased numbers of naïve Tregs may be involved in the pathogenesis of AIP.

Acute recurrent pancreatitis: An autoimmune disease?

In this review article, we will briefly describe the main characteristics of autoimmune pancreatitis and then we will concentrate on our aim, namely, evaluating the clinical characteristics of patients having recurrence of pain from the disease. In fact, the open question is to evaluate the possible presence of autoimmune pancreatitis in patients with an undefined etiology of acute pancreatitis and for this reason we carried out a search in the literature in order to explore this issue. In cases of recurrent attacks of pain in patients with “diopathic”pancreatitis, we need to keep in mind the possibility that our patients may have autoimmune pancreatitis. Even though the frequency of this disease seems to be quite low, we believe that in the future, by increasing our knowledge on the subject, we will be able to diagnose an ever-increasing number of patients having acute recurrence of pain from autoimmune pancreatitis.

Dual-phase CT of autoimmune pancreatitis: a multireader study

OBJECTIVE

The purpose of this study was to identify findings that aid in differentiating autoimmune pancreatitis from pancreatic carcinoma using dual-phase CT.

MATERIALS AND METHODS

Dual-phase CT scans of 74 patients (25 with autoimmune pancreatitis, 33 with pancreatic carcinoma, and 16 with a normal pancreas) were independently evaluated by three radiologists for enhancement of the pancreas; the presence of a capsule-like rim, peripancreatic strands, and pancreatic calcifications; pancreatic duct or bile duct changes; and renal involvement. The frequency of CT characteristics was compared between autoimmune pancreatitis and carcinoma. Interobserver agreement for the three reviewers for the assessment of CT characteristics was evaluated using kappa statistics.

RESULTS

Diffusely decreased enhancement of the pancreas (autoimmune pancreatitis vs carcinoma: 28% vs 3%; p = 0.02, kappa = 0.33-0.75), capsule-like rim (40% vs 9%; p = 0.009, kappa = 0.42-0.66), peripancreatic strands (60% vs 27%; p = 0.02, kappa = 0.45-0.54), pancreatic calcifications (32% vs 9%; p = 0.04, kappa = 0.14-0.47), bile duct wall enhancement (52% vs 6%; p = 0.0001, kappa = 0.28-0.47), and renal involvement (28% vs 0%; p = 0.002, kappa = 0.32-0.74) were more frequent in patients with autoimmune pancreatitis. Pancreatic duct dilation (24% vs 67%; p = 0.001, kappa = 0.65-0.73) and abrupt cutoff (16% vs 55%; p = 0.003, kappa = 0.60-0.65) were more frequent in patients with carcinoma.

CONCLUSION

Diffusely decreased enhancement of the pancreas, a capsule-like rim, bile duct enhancement, and renal involvement are useful signs of autoimmune pancreatitis.

Lymphoplasmacytic sclerosing pancreatitis (autoimmune pancreatitis): evaluation with multidetector CT

Lymphoplasmacytic sclerosing pancreatitis is a form of chronic pancreatitis characterized by a mixed inflammatory infiltrate that centers on the pancreatic ducts. It is a cause of benign pancreatic disease that can clinically mimic pancreatic cancer. Preoperative detection of lymphoplasmacytic sclerosing pancreatitis is important because patients usually respond to steroid therapy. Patients with lymphoplasmacytic sclerosing pancreatitis are often referred for computed tomography (CT) when they are suspected of having a pancreatic or biliary neoplasm; therefore, it is important to search for potential findings suggestive of lymphoplasmacytic sclerosing pancreatitis when typical findings of a pancreatic or biliary neoplasm are not found. Typical CT findings include diffuse or focal enlargement of the pancreas without dilatation of the main pancreatic duct. Focal enlargement is most commonly seen in the head of the pancreas, and the involved pancreas on contrast material-enhanced CT images may be iso-attenuating relative to the rest of the pancreas, or hypo-attenuating, especially during the early postcontrast phase. Thickening and contrast enhancement of the wall of the common bile duct and gallbladder may reflect inflammatory infiltrate and fibrosis associated with lymphoplasmacytic sclerosing pancreatitis. There are several features seen at CT that may help to differentiate lymphoplasmacytic sclerosing pancreatitis from pancreatic cancer, such as diffuse enlargement of the pancreas with minimal peripancreatic stranding in patients with obstructive jaundice, an absence of significant pancreatic atrophy, and an absence of significant main pancreatic duct dilatation. When these findings are encountered, clinical, other imaging, and serologic data should be evaluated.

Chronic pancreatitis: ultrasound, computed tomography, and magnetic resonance imaging features

Chronic pancreatitis is a progressive, irreversible inflammatory and fibrosing disease of the pancreas with clinical manifestations of chronic abdominal pain, weight loss, and permanent pancreatic exocrine and endocrine insufficiency. In the United States, a long history of heavy alcohol consumption is the most common cause of chronic pancreatitis. This review discusses the different modalities such as computed tomography, transabdominal and endoscopic ultrasound, magnetic resonance imaging/magnetic resonance cholangiopancreatography, and endoscopic retrograde cholangiopancreatography available to image chronic pancreatitis, along with their advantages and limitations. In addition, topics such as groove pancreatitis and autoimmune pancreatitis are examined, along with a discussion of distinguishing chronic pancreatitis from pancreatic adenocarcinoma.

Pancreatic cancer associated with autoimmune pancreatitis in remission

In January 2007, an 80-year-old man was admitted to our hospital for treatment of a pancreatic tumor. He had been diagnosed with autoimmune pancreatitis (AIP) in December 2003 for which steroid therapy had induced remission. In November 2006, tumor marker levels rapidly increased, and the patient was suspected of having pancreatic cancer based on imaging studies. The diagnosis was later confirmed by endoscopic ultrasound-guided fine-needle aspiration biopsy. Distinguishing AIP from pancreatic cancer is crucial; however, few previous reports have described any cases of pancreatic cancer associated with AIP. While several reports have speculated on the prognosis of AIP, natural courses of the disease remain uncertain. This report emphasizes that AIP can coexist with cancer.

Incidence of the focal type of autoimmune pancreatitis in chronic pancreatitis suspected to be pancreatic carcinoma: experience of a single tertiary cancer center

OBJECTIVE

With an increase in autoimmune pancreatitis (AIP) being reported, the focal type of AIP, which shows localized narrowing of the main pancreatic duct and focal swelling of the pancreas, has recently been recognized. Therefore, cases of focal-type AIP subjected to surgical intervention for presumptive malignancy might previously have been diagnosed as mass-forming chronic pancreatitis. The aim of this study was to elucidate the incidence of focal-type AIP in resected chronic pancreatitis at a single tertiary cancer center. The clinical and radiological features of focal-type AIP were also evaluated.

MATERIAL AND METHODS

We re-evaluated 15 patients who underwent pancreatic resection with a presumed diagnosis of pancreatic ductal adenocarcinoma, and who in the past had been diagnosed pathologically as having chronic pancreatitis.

RESULTS

Seven of 15 patients showed AIP, and the other 8 patients were diagnosed as having mass-forming chronic pancreatitis not otherwise specified by pathological retrospective examination. In other words, nearly half of the cases of resected chronic pancreatitis that were suspected to be pancreatic carcinoma preoperatively showed focal-type AIP. Regarding the characteristic findings of focal-type AIP, narrowing of the pancreatic duct on endoscopic retrograde pancreatography (ERP) might be diagnostic.

CONCLUSIONS

Focal-type AIP is not a rare clinical entity and might be buried in previously resected pancreatic specimens that in the past were diagnosed simply as mass-forming pancreatitis.

Autoimmune pancreatitis: A review

Autoimmune pancreatitis has emerged over the last 40 years from a proposed concept to a well established and recognized entity. As an efficient mimicker of pancreatic carcinoma, its early and appropriate recognition are crucial. With mounting understanding of its pathogenesis and natural history, significant advances have been made in the diagnosis of autoimmune pancreatitis. The characteristic laboratory features and imaging seen in autoimmune pancreatitis are reviewed along with some of the proposed diagnostic criteria and treatment algorithms.

Pancréatite auto-immune

Chronic autoimmune pancreatitis is an entity distinct from all other forms of chronic pancreatitis. It is expressed by signs of acute or chronic pancreatitis, sometimes associated with cholestatic jaundice. In imaging, it may appear as diffuse (duct destructive) or pseudotumoral lesions. These 2 aspects are probably different clinical forms of chronic autoimmune pancreatitis. Some autoimmune diseases are associated with chronic autoimmune pancreatitis, but not consistently. One such disease involves a bile disorder very similar to primary sclerosing cholangitis but responsive to corticosteroid treatment. Pancreatitis may be a sign of intestinal inflammatory diseases (and vice versa): testing for Crohn's disease and ulcerative rectocolitis is justified in patients with idiopathic pancreatitis. Chronic autoimmune pancreatitis must be routinely considered in patients with a pancreatic tumor that is for a clinical, epidemiologic, serologic or imaging reason not completely consistent with pancreatic adenocarcinoma. A short corticosteroid therapy (< 4 weeks) is probably less harmful in a patient with pancreatic adenocarcinoma than pancreatectomy (or chemotherapy) in patients with chronic autoimmune pancreatitis. Diagnosis depends on a body of clinical and radiologic evidence. The diagnostic value of serologic markers and especially of autoantibodies must be clarified in the future.

Ultrasonography of the pancreas. 1. Conventional imaging

Ultrasound imaging has made significant advances in recent years and plays an important role in the detection, characterization and staging of pancreatic diseases. Conventional ultrasonography (US) is a noninvasive imaging modality, which continues to be the first diagnostic step in the evaluation of the pancreas. Over its various decades of application, US have detected pancreatic pathology of great diversity. This article reviews the wide utility of US and the many examinations techniques, such as filling the stomach with water, changing the patient's position or suspending inspiration or expiration, allowing us to visualize all portions of the pancreas in a high percentage of patients.

The use of immunoglobulin g4 immunostaining in diagnosing pancreatic and extrapancreatic involvement in autoimmune pancreatitis

BACKGROUND & AIMS

Autoimmune pancreatitis (AIP) is recognized increasingly as a multisystem disorder. We evaluated the use of immunoglobulin (Ig)G4 immunostaining of pancreatic and extrapancreatic biopsy specimens to make a definitive diagnosis of AIP.

METHODS

Seventeen biopsy specimens and 3 gallbladder resections were assessed from 11 patients with clinical and radiologic features of AIP. Biopsy specimens from pancreas, liver, colon, stomach, duodenum, bone marrow, salivary gland, and kidney were analyzed morphologically, immunostained for IgG4-positive plasma cells, and compared with controls.

RESULTS

Positive IgG4 immunostaining enabled a definitive diagnosis in 10 of 11 (91%) AIP patients. In both pancreatic and extrapancreatic tissues, high levels of IgG4 immunostaining (>10 IgG4-positive plasma cells/high-power field) were found in 17 of 20 (85%) specimens from AIP patients compared with 1 of 175 (0.6%) specimens from controls (P < .05). Positive extrapancreatic IgG4 immunostaining was found in 8 of 11 (73%) patients, including all those with diagnostic features in the pancreas. Increased tissue IgG4 was found irrespective of serum IgG4 level.

CONCLUSIONS

The finding of IgG4 immunostaining within a range of clinically involved tissues supports the hypothesis that AIP is a multisystem disease. Positive IgG4 immunostaining in extrapancreatic tissues may allow a definitive diagnosis of AIP to be made in those with evidence of pancreatic disease, without the necessity of pancreatic biopsy or surgical exploration. Immunostaining of involved tissue for IgG4 may be particularly useful when AIP is suspected clinically but the serum IgG4 level is normal.

Focal lymphoplasmacytic sclerosing pancreatitis: radiological-pathological correlation

OBJECTIVE

To correlate cross-sectional imaging findings with histological results in patients with histopathologically proven lymphoplasmacytic sclerosing pancreatitis (LSP) after surgery.

METHODS

Four cases of resectable pancreatic lesions that were proven to represent LSP are presented in our study. All patients were thought to harbor malignancy. A detailed research in patients' records was retrospectively done concerning clinical presentation and imaging studies.

RESULTS

Characteristic imaging findings consistent with fibrotic changes were evident in only one case on magnetic resonance imaging. A discrete mass was evident on imaging in 2 patients that correlated well with pathology results. In the other patients, the extent of inflammatory changes on microscopic examination correlated well with the degree of pancreatic head enlargement on imaging studies.

CONCLUSIONS

Lymphoplasmacytic sclerosing pancreatitis is a particular form of benign inflammatory pancreatic disease that is extremely difficult to diagnose preoperatively. Familiarization with the variable imaging findings is essential and may result in the reduction of the number of patients with LSP who undergo surgical resection.

[Diffuse primary fat replacement of the pancreas: an unusual cause of steatorrhea]

Diffuse and primitive fat replacement of the exocrine pancreas is a rare cause of exocrine pancreatic insufficiency in adults. We report two adult patients with chronic diarrhoea and steatorrhea whose morphologic abnormalities revealed diffuse fat replacement of the pancreas. Tomodensitometry detected diffuse characteristic abnormalities with fat intermixed with normal pancreatic lobules or a "vanishing pancreas". In one patient, magnetic resonance imaging and echo-endoscopy suggested abnormalities. Administration of pancreatic extracts improved symptoms.

A case of sclerosing cholangitis with autoimmune pancreatitis evaluated by FDG-PET

The extrapancreatic bile duct lesions in autoimmune pancreatitis are termed sclerosing cholangitis (SC with AIP), which is known to complicate AIP somewhat more frequently than other extrapancreatic lesions. In cases of SC with AIP, differentiation from primary SC, pancreatic cancer, and bile duct cancer is often difficult. In our patient, pancreatic cancer had to be ruled out at admission, given the findings of obstructive jaundice, pancreatic duct stenosis, and swelling of the pancreas. Fluorine-18-fluorodeoxyglucose positron emission tomography was useful in checking for the presence of extrapancreatic lesions, including SC, and was also useful in the evaluation of the response to steroid therapy for following the course of AIP.

Autoimmune pancreatitis

Autoimmune pancreatitis is a rare systemic fibrotic inflammatory disorder that can affect organs such as the bile ducts, salivary glands, and retroperitoneal lymph nodes, in addition to the pancreas. Morphological characteristics of autoimmune pancreatitis include a diffusely enlarged 'sausage-shaped' pancreas and an irregularly narrowed duct of Wirsung. According to the revised Japan Pancreas Society criteria, the diagnosis of autoimmune pancreatitis requires that one or more secondary serologic or histologic criteria are also met: the presence of autoantibodies, elevated levels of gamma-globulins, IgG or IgG(4), a lymphoplasmacytic infiltrate, or pancreatic fibrosis. The presence in any affected organ of a lymphoplasmacytic inflammatory infiltrate containing greater than 10 IgG(4)-positive cells per high-power field is pathognomonic for autoimmune pancreatitis. Precise data on the incidence and prevalence of autoimmune pancreatitis are currently not available because most reports involve either limited patient series or resection specimen cohorts. New diagnostic tools and further studies of the underlying pathophysiology and prognosis of autoimmune pancreatitis are needed for adequate and effective treatment strategies to be developed. The most crucial issue when caring for patients with suspected autoimmune pancreatitis is to differentiate autoimmune pancreatitis from pancreatic carcinoma, because pancreatic carcinoma requires surgery, whereas autoimmune pancreatitis responds well to steroid treatment.