Autoimmune pancreatitis

Autoimmune Pancreatitis Mimicking Obstructive Pancreatic Neuroendocrine Tumor

Autoimmune pancreatitis (AIP), otherwise known as non-alcoholic destructive pancreatitis or sclerosing pancreatitis, is a rare form of chronic pancreatitis that is clinically significant due to its potential to mimic pancreatic cancer. In our case, we present a 64-year-old male with a past medical history of type 2 diabetes and epigastric abdominal pain for one year who presented with worsening epigastric abdominal pain, 12-pound weight loss, and vomiting and was found to have a neuroendocrine tumor on a preliminary pathology report, while official pathology later came back stating AIP. Distinguishing between autoimmune pancreatitis (AIP) and pancreatic cancer is vital, given the stark contrast in their treatment and prognosis. In our case, preliminary pathology suggested a neuroendocrine tumor, prompting consultation with oncology. Utilizing invasive testing like EUS-FNA, we obtained an official diagnosis and prevented the patient from undergoing unnecessary treatments and interventions. Our case shows the importance of further testing when a patient presents with a fast-growing obstructive pancreatic mass. While searching the literature, there are no previously documented cases of an AIP mass as large as our patients and as fast-growing.

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.

Hybrid kappa\lambda antibody is a new serological marker to diagnose autoimmune pancreatitis and differentiate it from pancreatic cancer

The only generally accepted serological marker currently used for the diagnosis of autoimmune pancreatitis (AIP) is IgG4. Our aim was mainly to determine whether hybrid κ\λ antibody can help to diagnose AIP and to differentiate it from pancreatic cancer. We established an enzyme-linked immunosorbent assay (ELISA) system to measure the levels of hybrid κ\λ antibodies in human sera. Sera were obtained from 338 patients, including 61 with AIP, 74 with pancreatic cancer, 50 with acute pancreatitis, 40 with ordinary chronic pancreatitis, 15 with miscellaneous pancreatic diseases, and 98 with normal pancreas. Our study showed levels of hybrid κ\λ antibodies in the AIP group were significantly higher than in the non-AIP group (P < 0.001). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the diagnosis of AIP were 80.3%, 91%, 66.2% and 95.5% respectively. Furthermore, the combined measurement of serum hybrid κ\λ antibody and IgG4 tended to increase the sensitivity although the difference was not statistically significant (90.2% vs. 78.7%, P = 0.08), compared to measurement of IgG4 alone. Our findings suggest that hybrid κ\λ antibody could be a new serological marker to diagnose AIP and differentiate it 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.

Diagnosis of autoimmune pancreatitis by EUS-FNA by using a 22-gauge needle based on the International Consensus Diagnostic Criteria

BACKGROUND

It is controversial whether EUS-guided FNA by using 22-gauge (G) needles is useful for the diagnosis or evaluation of autoimmune pancreatitis (AIP).

OBJECTIVE

To evaluate the usefulness of EUS-FNA by 22-G needles for the histopathological diagnosis of AIP.

DESIGN

A retrospective study.

SETTING

Single academic center.

PATIENTS

A total of 273 patients, including 25 with AIP, underwent EUS-FNA and histological examinations.

RESULTS

EUS-FNA by using 22-G needles provided adequate tissue samples for histopathological evaluation because more than 10 high-power fields were available for evaluation in 20 of 25 patients (80%). The mean immunoglobulin G4-positive plasma cell count was 13.7/high-power field. Obliterative phlebitis was observed in 10 of 25 patients (40%). In the context of the International Consensus Diagnostic Criteria for AIP, 14 and 6 of 25 patients were judged to have level 1 (positive for 3 or 4 items) and level 2 (positive for 2 items) histological findings, respectively, meaning that 20 of 25 patients were suggested to have lymphoplasmacytic sclerosing pancreatitis based on the International Consensus Diagnostic Criteria. The diagnosis in 1 patient was type 2 AIP because a granulocytic epithelial lesion was identified in this patient.

LIMITATIONS

A retrospective study with a small number of patients.

CONCLUSIONS

The results of this study suggest that EUS-FNA by using 22-G needles provides tissue samples adequate for histopathological evaluation and greatly contributes to the histological diagnosis of AIP.

Nationwide epidemiological survey of autoimmune pancreatitis in Japan

OBJECTIVES

To clarify the clinicoepidemiological features of autoimmune pancreatitis (AIP) in Japan, the nationwide survey was conducted.

METHODS

Patients with AIP who had visited the selected hospitals in 2007 were surveyed. Autoimmune pancreatitis was diagnosed according to the Japanese clinical diagnostic criteria 2006. The study consisted of 2-stage surveys: the number of patients with AIP was estimated by the first questionnaire and their clinical features were assessed by the second questionnaire.

RESULTS

The estimated total number of AIP patients in 2007 was 2790 (95% confidence interval, 2540-3040), with an overall prevalence rate of 2.2 per 100,000 populations. The number of patients, who were newly diagnosed as AIP, was estimated to be 1120 (95% confidence interval, 1000-1240), with an annual incidence rate of 0.9 per 100,000 populations. Sex ratio (male to female) was 3.7, and the mean (SD) age was 63.0 (11.4) years. Among the 546 patients whose clinical information was obtained, 87.6% of the patients presented high serum immunoglobulin G4 levels (≥ 135 mg/dL), and 83% received steroid therapy.

CONCLUSIONS

The data represent the current clinical features of AIP in Japan. From the results, most AIP patients in Japan can be categorized to type 1 AIP according to the recent classification of AIP.

Demystifying seronegative autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis (AIP) has been classified into type 1 and type 2 subtypes. Serum immunoglobulin G4 (IgG4) elevation characterizes type 1 AIP. Type 2 AIP and a subset of type 1 AIP are seronegative, i.e., have normal serum IgG4 levels.

AIM

We compared the profiles of the three subsets of AIP to identify the unique characteristics of seronegative type 1 AIP and type 2 AIP.

METHODS

We compared the clinical profiles of 69 seropositive type 1 AIP patients, 21 seronegative type 1 AIP patients and 22 type 2 AIP patients.

RESULTS

Among type 1 AIP, seronegative group had similar clinical profiles when compared to seropositive group except that they were more likely to undergo surgical resection than seropositive patients (p = 0.001). Seronegative type I AIP patients were older (61.9 ± 13.7 vs 45.3 ± 17.4; p = 0.004), and differed in the occurrence of other organ involvement (OOI) (71.4% vs 0%; p < 0.001) and disease relapse (33.3% vs 0%; p = 0.005) when compared with type 2 AIP. All seronegative type 1 AIP patients had at least one of the following -OOI, disease relapse, and age >50 years while none of the type 2 AIP had OOI or disease relapse.

CONCLUSIONS

Seronegative and seropositive type 1 AIP patients have similar clinical profiles, which are distinct from that of type 2 AIP. Among the seronegative AIP group, patients are more likely to have type 1 AIP rather than type 2 AIP if they are older than 50 years or have OOI or disease relapse.

Expression and regulation of chemokines in murine and human type 1 diabetes

More than one-half of the ~50 human chemokines have been associated with or implicated in the pathogenesis of type 1 diabetes, yet their actual expression patterns in the islet environment of type 1 diabetic patients remain, at present, poorly defined. Here, we have integrated a human islet culture system, murine models of virus-induced and spontaneous type 1 diabetes, and the histopathological examination of pancreata from diabetic organ donors with the goal of providing a foundation for the informed selection of potential therapeutic targets within the chemokine/receptor family. Chemokine (C-C motif) ligand (CCL) 5 (CCL5), CCL8, CCL22, chemokine (C-X-C motif) ligand (CXCL) 9 (CXCL9), CXCL10, and chemokine (C-X3-C motif) ligand (CX3CL) 1 (CX3CL1) were the major chemokines transcribed (in an inducible nitric oxide synthase-dependent but not nuclear factor-κB-dependent fashion) and translated by human islet cells in response to in vitro inflammatory stimuli. CXCL10 was identified as the dominant chemokine expressed in vivo in the islet environment of prediabetic animals and type 1 diabetic patients, whereas CCL5, CCL8, CXCL9, and CX3CL1 proteins were present at lower levels in the islets of both species. Of importance, additional expression of the same chemokines in human acinar tissues emphasizes an underappreciated involvement of the exocrine pancreas in the natural course of type 1 diabetes that will require consideration for additional type 1 diabetes pathogenesis and immune intervention studies.

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

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

Autoimmune pancreatitis versus pancreatic cancer: a comprehensive review with emphasis on differential diagnosis

BACKGROUND

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis with a discrete pathophysiology, occasional diagnostic radiological findings, and characteristic histological features. Its etiology and pathogenesis are still under investigation, especially during the last decade. Another aspect of interest is the attempt to establish specific criteria for the differential diagnosis between autoimmune pancreatitis and pancreatic cancer, entities that are frequently indistinguishable.

DATA SOURCES

An extensive search of the PubMed database was performed with emphasis on articles about the differential diagnosis between autoimmune pancreatitis and pancreatic cancer up to the present.

RESULTS

The most interesting outcome of recent research is the theory that autoimmune pancreatitis and its various extra-pancreatic manifestations represent a systemic fibro-inflammatory process called IgG4-related systemic disease. The diagnostic criteria proposed by the Japanese Pancreatic Society, the more expanded HISORt criteria, the new definitions of histological types, and the new guidelines of the International Association of Pancreatology help to establish the diagnosis of the disease types.

CONCLUSION

The valuable help of the proposed criteria for the differential diagnosis between autoimmune pancreatitis and pancreatic cancer may lead to avoidance of pointless surgical treatments and increased patient morbidity.

Distinguishing pancreatic cancer from autoimmune pancreatitis

Both autoimmune pancreatitis (AIP) and pancreatic cancer frequently present with obstructive jaundice. However, AIP is a rare disease and its diagnosis carries vastly different therapeutic and prognostic implications compared with that of pancreatic cancer. The clinical challenge is to distinguish AIP from pancreatic cancer, because the price of misdiagnosis can be heavy. Recently, two strategies for differentiating AIP from pancreatic cancer were published, one from Japan and the other from the United States. The Japanese strategy relies on cross-sectional imaging, endoscopic retrograde pancreatogram, and serum IgG4. The American strategy uses imaging (CT scan), serology (serum IgG4), and evidence of other organ involvement (on CT scan) as the first tier of tests. If the differentiation cannot be made by these methods, a core biopsy of the pancreas, steroid trial, or surgical resection is recommended. The two strategies reflect differences in clinical practice and local preferences in the use of certain diagnostic tests. However, both strategies require thorough familiarity with the diseases and the tests being used.

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

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

Distinguishing pancreatic cancer from autoimmune pancreatitis: a comparison of two strategies

Autoimmune pancreatitis is a rare disease which closely mimics pancreatic cancer in its presentation. It is important for clinicians to distinguish one from the other due to vastly different therapeutic and prognostic implications. We compared 2 recently proposed strategies, 1 from Japan and the other from the United States, to distinguish autoimmune pancreatitis from pancreatic cancer. While both strategies have inherent strengths and weaknesses, we believe that the best features of both need prospective validation. The strategy proposed from Japan is simple to use, but is based on a small number of patients and is heavily dependent on imaging criteria. The American strategy while based on a bigger sample of patients is complicated and is most useful in expert hands. Additionally, differences in clinical practice and local preference in the use of certain diagnostic tests need to be considered while adopting either strategy.

Sclerosing cholangitis associated with autoimmune pancreatitis differs from primary sclerosing cholangitis

AIM: To clarify the characteristic features of biliary lesions in patients with autoimmune pancreatitis (AIP) and compare them with those of primary sclerosing cholangitis (PSC).

METHODS: The clinicopathological characteristics of 34 patients with sclerosing cholangitis (SC) associated with AIP were compared with those of 4 patients with PSC.

RESULTS: SC with AIP occurred predominantly in elderly men. Obstructive jaundice was the most frequent initial symptom in SC with AIP. Only SC patients with AIP had elevated serum IgG4 levels, and sclerosing diseases were more frequent in these patients. SC patients with AIP responded well to steroid therapy. Segmental stenosis of the lower bile duct was observed only in SC patients with AIP, but a beaded and pruned-tree appearance was detected only in PSC patients. Dense infiltration of IgG4-positive plasma cells was detected in the bile duct wall and the periportal area, as well as in the pancreas, of SC patients with AIP.

CONCLUSION: SC with AIP is distinctly different from PSC. The two diseases can be discriminated based on cholangiopancreatographic findings and serum IgG4 levels.

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.

Recognizing immunoglobulin G4 related overlap syndromes in patients with pancreatic and hepatobiliary diseases

The first description of autoimmune pancreatitis and elevated serum immunoglobulin-G4 (IgG4) in 2001 heralded further reports of several related autoimmune diseases with raised IgG4 levels. It is now recognized that a spectrum of overlap syndromes associated with increased IgG4 and biopsy evidence of IgG4-producing plasma cells, which has now been convincingly linked with cholangitis, autoimmune hepatitis, Sjögren's syndrome, nephritis and retroperitoneal fibrosis. Collectively, this disease cluster is referred to as IgG4-related systemic disease. The importance of making the correct diagnosis is underscored by the management of individuals with IgG4-related systemic disease. In the first instance, patients generally have a dramatic response to immunosuppressive therapy, whereas patients with other forms of cholangitis and pancreatitis do not. Also, surgical management of pancreatic malignancy can be avoided once the correct diagnosis of IgG4-related disease has been made. In the present review, an overview of the current information regarding the role of IgG4 and IgG4-positive cells affecting the biliary system, pancreas and liver is provided.

Autoimmune pancreatitis

PURPOSE OF REVIEW

Autoimmune pancreatitis (AIP) is an increasingly recognized clinical condition. Our objective is to provide a concise review of the advances in the past year in our understanding of AIP.

RECENT FINDINGS

In a hospital survey from Japan, the prevalence of AIP was estimated at 0.82 per 100,000 individuals. The pathogenesis of AIP remains unclear but a recent report noted that T helper type 2 and T regulatory cells predominantly mediate the immune reaction in AIP. Genetic associations that may predispose to relapse of AIP were reported. Multiple case series further described the clinical profile of AIP and its extrapancreatic manifestations. A large series on immunoglobulin G4 (IgG4)-associated cholangitis noted that patients with IgG4-associated cholangitis presented with obstructive jaundice and had increased serum IgG4 levels and IgG4-positive cells in bile duct biopsy specimens. Tissue IgG4 staining is likely to be a useful adjunct to serological diagnosis. AIP is steroid-responsive but maintaining remission continues to remain challenging. Presently low-dose steroids or immunomodulators are being used but efficacy of these medications remains to be determined.

SUMMARY

There has been significant progress in understanding the clinical profile of AIP but knowledge of pathogenesis remains limited. Treatment practices vary widely and management of refractory disease continues to be challenging.

Autoimmune pancreatitis

Autoimmune pancreatitis is the pancreatic manifestation of a systemic disorder that affects various organs, including the bile duct, retroperitoneum, kidney, and parotid and lacrimal glands. It represents a recently described subset of chronic pancreatitis that is immune mediated and has unique histologic, morphologic, and clinical characteristics. A hallmark of the disease is its rapid response to corticosteroid treatment. Although still a rare disease, autoimmune pancreatitis is increasingly becoming recognized clinically, leading to evolution in the understanding of its prognosis, clinical characteristics, and treatment.

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.

Value of serum IgG4 in the diagnosis of autoimmune pancreatitis and in distinguishing it from pancreatic cancer

OBJECTIVES

To determine the sensitivity and specificity of elevated serum IgG4 level for the diagnosis of autoimmune pancreatitis (AIP) and its ability to distinguish AIP from pancreatic cancer, its main differential diagnosis.

METHODS

We measured serum IgG4 levels (normal 8-140 mg/dL) in 510 patients including 45 with AIP, 135 with pancreatic cancer, 62 with no pancreatic disease, and 268 with other pancreatic diseases.

RESULTS

Sensitivity, specificity, and positive predictive values for elevated serum IgG4 (>140 mg/dL) for diagnosis of AIP were 76%, 93%, and 36%, respectively, and 53%, 99%, and 75%, respectively, for IgG4 of >280 mg/dL. Among subjects with elevated IgG4, non-AIP subjects (N = 32) differed from AIP subjects (N = 34) in that they were more likely to be female (45%vs 9%, P < 0.001), less likely to have serum IgG4 >280 mg/dL (13%vs 71%, P < 0.001), or elevation of total IgG (16%vs 56%, P < 0.001). Serum IgG4 levels were elevated in 13/135 (10%) pancreatic cancer patients; however, only 1% had IgG4 levels >280 mg/dL compared with 53% of AIP. Compared with AIP, pancreatic cancer patients were more likely to have CA19-9 levels of >100 U/mL (71%vs 9%, P < 0.001).

CONCLUSION

Elevated serum IgG4 levels are characteristic of AIP. However, mild (<2-fold) elevations in serum IgG4 are seen in up to 10% of subjects without AIP including pancreatic cancer and cannot be used alone to distinguish AIP from pancreatic cancer. Because AIP is uncommon, IgG4 elevations in patients with low pretest probability of having AIP are likely to represent false positives.

The relationship of salivary gland function to elevated serum IgG4 in autoimmune pancreatitis

OBJECTIVE

To compare salivary gland function in autoimmune pancreatitis (AIP) patients with and without an elevated serum IgG4 concentration.

PATIENTS AND METHODS

We allocated 14 AIP patients into 2 groups: one group had high (>135 mg/dL) serum IgG4 and the other low serum IgG4. Sialochemistry and submandibular and parotid gland scintigraphy were done in these patients.

RESULTS

Serum IgG4 levels were elevated in 10 patients. Bilateral submandibular gland swelling was present in 5 patients with a high serum IgG4; there was no swelling in patients with a low serum IgG4. The salivary Na+ concentration was increased significantly in both patient groups (p<0.01) compared to controls. The beta2-microglobulin concentration was significantly higher in patients with a high serum IgG4 than in those with a low serum IgG4 (p<0.05) and controls (p<0.01). On submandibular and parotid gland scintigraphy, both the ratio of the cumulative peak count to the injected radionuclide (PCR) and the washout ratio (WR) were significantly lower in the high serum IgG4 group than in controls (p<0.01). In the low serum IgG4 group, the PCR on submandibular gland scintigraphy, and the PCR and WR on parotid gland scintigraphy were significantly lower than in controls (p<0.05, p<0.01 and p<0.05, respectively). On submandibular gland scintigraphy, the PCR was significantly lower in the high serum IgG4 group than in the low serum IgG4 group (p<0.05).

CONCLUSIONS

Salivary gland function was impaired in all AIP patients, but it was more impaired in patients with a high serum IgG4 than in those with a low serum IgG4.

Autoimmune pancreatitis associated with a large pancreatic pseudocyst

Pancreatic cystic lesions comprise various entities with different histopathological characteristics and their differential diagnosis is often a challenge for clinicians. Autoimmune pancreatitis (AIP) is usually not considered in the differential diagnosis of cystic lesions, but often mimics the morphological aspects of pancreatic neoplasm. We report the case of a 64-year-old male patient with a cystic pancreatic head lesion (diameter 5 cm) and stenosis of the distal bile duct requiring repeated stenting. Because of the clinical presentation together with moderate elevation of serum CA19-9 and massive elevation of cyst fluid CA19-9 (122.695 U/L; normal range: < 37.0 U/L), the patient underwent explorative laparotomy and pylorus preserving partial pancreaticoduodenectomy. Histology revealed surprisingly AIP with an inflammatory pseudocyst. In conclusion, cyst fluid analysis of tumor markers and cyst fluid cytology lack high accuracy to clearly differentiate cystic pancreatic lesions. Although AIP is rarely associated with pseudocysts, the disease has to be considered in the differential diagnosis of cystic pancreatic lesions. Early examination of serum IgG, IgG₄ and auto-antibodies might save these patients from unnecessary endoscopical and surgical procedures.

Autoimmune pancreatitis: proposal of IgG4-related sclerosing disease

Autoimmune pancreatitis (AIP) is a peculiar type of pancreatitis of presumed autoimmune etiology. Many new clinical aspects of AIP have been clarified during the past 10 years, and AIP has become a distinct entity recognized worldwide. However, its precise pathogenesis or pathophysiology remains unclear. As AIP dramatically responds to steroid therapy, accurate diagnosis of AIP is necessary to avoid unnecessary surgery. Characteristic dense lymphoplasmacytic infiltration and fibrosis in the pancreas may prove to be the gold standard for diagnosis of AIP. However, since it is difficult to obtain sufficient pancreatic tissue, AIP should be diagnosed currently based on the characteristic radiological findings (irregular narrowing of the main pancreatic duct and enlargement of the pancreas) in combination with serological findings (elevation of serum gamma-globulin, IgG, or IgG4, along with the presence of autoantibodies), clinical findings (elderly male preponderance, fluctuating obstructive jaundice without pain, occasional extrapancreatic lesions, and favorable response to steroid therapy), and histopathological findings (dense infiltration of IgG4-positive plasma cells and T lymphocytes with fibrosis and obliterative phlebitis in various organs). It is apparent that elevation of serum IgG4 levels and infiltration of abundant IgG4-positive plasma cells into various organs are rather specific to AIP patients. We propose a new clinicopathological entity, "IgG4-related sclerosing disease", and suggest that AIP is a pancreatic lesion reflecting this systemic disease.

Management of pain in small duct chronic pancreatitis

Small duct chronic pancreatitis (CP) is defined by a nondilated main pancreatic duct, and the morphological and clinical features of chronic pancreatitis with pain are the most prominent symptoms. Current treatment strategies are based on pain history and the location and extent of disease. Traditionally, radical pancreatic resectional procedures have been carried out for small duct CP, especially with an associated head mass of uncertain aetiology. Based on the information from five randomized trials, the duodenum-preserving pancreatic head resection and its modifications have proven to provide excellent long-term pain relief and to be superior to more radical operations. Therefore, these procedures can be considered the standard for small duct CP with head dominant disease. The longitudinal V-shaped excision of the ventral pancreas combines extensive drainage and a limited resection and offers good pain relief in diffuse small duct CP. However, long-term results and larger series are awaited for definite conclusions. Thoracoscopic splanchnicectomy and endosonography-guided celiac plexus blocks require controlled trials before their routine use. This article provides an overview about the current and evidence-based pain management in small duct CP.