Immunoglobulin G4 immunostaining of gastric, duodenal, or colonic biopsies is not helpful for the diagnosis of autoimmune pancreatitis

A Clinical and Pathophysiological Overview of Intestinal and Systemic Diseases Associated with Pancreatic Disorders: Causality or Casualty?

The relationship between chronic intestinal disease, including inflammatory bowel disease (IBD) and celiac disease (CelD), and pancreatic disorders has been little investigated. Although an increased risk of acute pancreatitis (AP), exocrine pancreatic insufficiency with or without chronic pancreatitis, and chronic asymptomatic pancreatic hyperenzymemia have been described in these patients, the pathogenetic link remains unclear. It may potentially involve drugs, altered microcirculation, gut permeability/motility with disruption of enteric-mediated hormone secretion, bacterial translocation, and activation of the gut-associated lymphoid tissue related to chronic inflammation. In addition, the risk of pancreatic cancer seems to be increased in both IBD and CelD patients with unknown pathogenesis. Finally, other systemic conditions (e.g., IgG4-related disease, sarcoidosis, vasculitides) might affect pancreatic gland and the intestinal tract with various clinical manifestations. This review includes the current understandings of this enigmatic association, reporting a clinical and pathophysiological overview about this topic.

The features and clinical outcomes of inflammatory bowel disease associated with autoimmune pancreatitis: A greater awareness is needed

The prevalence of inflammatory bowel disease (IBD) has been described in 5% to 40% of autoimmune pancreatitis (AIP) patients. The aim of our study was to evaluate the prevalence, endoscopic features, and outcome of IBD in association with AIP.A retrospective analysis including all consecutive patients with AIP and a histological diagnosis of IBD from 2010 to 2020 was performed. Demographical data, AIP, and IBD features, as well as clinical course, were recorded.Among 267 AIP patients, 45 were diagnosed with ulcerative colitis (UC) (27 men, mean age 31.6), all with a diagnosis of type 2 AIP. The most frequent presentation of AIP was acute pancreatitis (55.5%). Both diffuse (51.1%) and focal (48.9%) pancreatic involvement were observed. The AIP relapse rate was 11.1% over a mean follow-up of 55 months. In 69% of patients, the interval time between the diagnosis of AIP and UC was <1 year. When UC was present at AIP onset, UC was in clinical remission in 50% of patients. Fecal calprotectin levels, when available, were elevated in 86.6% of these patients. Mostly, mild-moderate pancolitis was initially diagnosed (55.5%). During follow-up, escalation therapy for UC was required in 40% of patients after a mean time of 45 months. Two patients (4.4%) underwent colectomy.The prevalence of UC in AIP patients was 17%. Mild pancolitis with a low rate of colectomy was found. Greater awareness is needed to avoid a delayed diagnosis of UC, and the dosage of fecal calprotectin levels could have a role in this setting.

[Immunohistochemical signs of IgG4-related disease in patients with inflammatory bowel diseases]

OBJECTIVE

To determine immunohistochemical features of IgG4-related disease in patients with inflammatory bowel diseases (IBD).

MATERIAL AND METHODS

Immunohistochemical testing of colonic biopsy material from 35 patients with IBD (24 cases of ulcerative colitis and 11 cases of Crohn's disease) was carried out using IgG, IgG4 and CD138 antibodies. The number of IgG4- and CD138-positive cells was counted in high power field of microscope (×400). Patient selection was random.

RESULTS

IgG4-positive cells were detected in the colonic mucosa of 5 patients with ulcerative colitis. The age of the patients ranged from 24 to 47 years. Two patients had a total, and three had a left-sided lesion of the colon. The anamnesis of the disease ranged from 3 to 13 years. The number of positively stained cells in the reaction with the antibody to IgG4 varied from 2 to 50 in high power field of microscope. We were able to detect over 10 IgG4-positive cells in 3 females aged 28, 30 and 31 years with a long history of ulcerative colitis (5, 4 and 3 years, respectively). Two patients had a total lesion of the colon, all three had an exacerbation of the disease, and a morphological study revealed chronic diffuse active erosive colitis. A high degree of histological activity and pronounced diffuse basal plasmacytosis were noted. In one of the cases, the infiltrate captured the muscular lamina of the mucosa and areas of the submucosa.

CONCLUSIONS

IgG4-positive cells in the inflammatory infiltrate, including those with an excess of more than 10 in the field of view of the microscope at high magnification, can be observed in patients with ulcerative colitis with severe and prolonged course of the disease. To classify this colitis as a manifestation of an IgG4-related disease, the results of immunohistochemical studies alone are not enough. It is required to accumulate a larger number of observations, as well as to search for other diagnostic criteria for an IgG4-related disease in these patients.

Role of Endoscopic Procedures in the Diagnosis of IgG4-Related Pancreatobiliary Disease

The emergence of the disease entity of glucocorticoid-responsive systemic immunoglobulin G4 (IgG4)-related pancreatobiliary disease has generated substantial attention among the international gastroenterology society. IgG4-related pancreatobiliary disease includes type 1 autoimmune pancreatitis (AIP) and IgG4-related sclerosing cholangitis (IgG4-SC). The typical manifestations of IgG4-related pancreatobiliary disease are cholestatic liver dysfunction, obstructive jaundice, and weight loss, although it may present with no clinical symptoms. Since it mimics tumors on imaging, AIP/IgG4-SC may often be misdiagnosed as pancreatic or biliary cancer. The endoscopic armamentarium for the diagnosis of IgG4-related pancreatobiliary disease includes endoscopic ultrasonography, intraductal ultrasonography, endoscopic retrograde cholangiopancreatography, and cholangioscopy. The role of endoscopic tissue acquisition is two-fold in the diagnosis of IgG4-related pancreatobiliary disease: exclusion of cancer and procurement of histopathological proof for diagnosis of AIP/IgG4-SC, which can also be achieved by adding the immunohistochemistry for IgG4. Our review article addresses the role of various endoscopic examinations in diagnosing IgG4-related pancreatobiliary disease, focusing on the differentiation of this condition from pancreatobiliary malingnancies.

The use of immunohistochemistry for IgG4 in the diagnosis of autoimmune pancreatitis: A systematic review and meta-analysis

BACKGROUND

The diagnosis of autoimmune pancreatitis (AIP) remains challenging, especially when serum IgG4 is normal or imaging features are indeterminate. We performed a systematic review and meta-analysis to evaluate the performance of IgG4 immunostaining of pancreatic, biliary, and ampullary tissues as a diagnostic aid for AIP.

METHODS

A comprehensive literature search of the PubMed, EMBASE, and Ovid MEDLINE databases was conducted until February 2020. The methodological quality of each study was assessed according to the Quality Assessment of Diagnostic Accuracy Studies checklist. A random-effects model was used to summarize the diagnostic odds ratio and other measures of accuracy.

RESULTS

The meta-analysis included 20 studies comprising 346 patients with AIP and 590 patients with other pancreatobiliary diseases, including 371 pancreatobiliary malignancies. The summary estimates for tissue IgG4 in discriminating AIP and controls were as follows: diagnostic odds ratio 38.86 (95% confidence interval (CI), 18.70-80.75); sensitivity 0.64 (95% CI, 0.59-0.69); specificity 0.93 (95% CI, 0.91-0.95). The area under the curve was 0.939 for tissue IgG4 in discriminating AIP and controls. Subgroup analysis revealed no significant difference in diagnostic accuracy according to control groups (pancreatobiliary cancer versus other chronic pancreatitis) and sampling site (pancreas versus bile duct/ampulla).

CONCLUSIONS

Current data demonstrate that IgG4 immunostaining of pancreatic, biliary, and ampullary tissue has a high specificity but moderate sensitivity for diagnosing AIP. IgG4 immunostaining may be useful in supporting a diagnosis of AIP when AIP is clinically suspected, but a combination of imaging and serology does not provide a conclusive diagnosis.

Can colonic inflammatory polyp with numerous immunoglobulin G4-positive plasma cells represent a colonic manifestation of immunoglobulin G4-related disease? A case report

We present an asymptomatic case of a 79-year-old Japanese man who had a 6 mm colonic inflammatory polyp with numerous immunoglobulin G4 (IgG4)-positive plasma cells. No symptoms or abnormal laboratory data, such as changes in serum IgG4 levels, were found at the time of diagnosis or during the 1 year of follow-up thereafter. Additionally, no diffuse/localized swelling or masses were found in organs, except for colonic polyps, by abdominal computed tomography 1 year prior to the polypectomy. Inflammatory myofibroblastic tumor was unlikely from the lack of spindle cell proliferation and ALK immunoreactivity. This is the first case of this colonic polyp in an asymptomatic person. This polyp could be probable for single organ manifestation of IgG4-related disease (IgG4-RD), according to the comprehensive diagnostic criteria for IgG4-RD published in 2012; however, colonic manifestation of IgG4-RD has not been clarified owing to its rarity, and colon-specific criteria for IgG4-RD have not been proposed. Thus, we could not definitively establish the colonic polyp as IgG4-RD. Therefore, careful clinicopathological evaluation is needed to reveal whether this colonic polyp represents a nonspecific inflammatory response or an early manifestation of IgG4-RD.

Value of anti-plasminogen binding peptide, anti-carbonic anhydrase II, immunoglobulin G4, and other serological markers for the differentiation of autoimmune pancreatitis and pancreatic cancer

The diagnosis of autoimmune pancreatitis (AIP) and its differential diagnosis from pancreatic cancer (PC) can be challenging. In this retrospective study, we aimed to evaluate the value of anti-plasminogen binding peptide (a-PBP), immunoglobulin G4 (IgG4), and anti-carbonic anhydrase-II (a-CA-II), together with other serological markers whose value is not fully elucidated.The serum levels of a-PBP, IgG4, IgG, anti-nuclear antibodies (ANA), anti-lactoferrin (a-LF), a-CA-II, and rheumatoid factor (RF) were evaluated in patients with AIP (n = 29), PC (n = 17), pancreatic neuroendocrine neoplasm (P-NEN, n = 12), and alcoholic chronic pancreatitis (ACP, n = 41). ANCA were measured in the AIP patients.There was no statistically significant difference in mean a-PBP values in AIP compared with PC. A ROC curve showed that, when using a cut-off of 38.3 U, low values of a-PBP had a sensitivity and specificity of 45% and 71% for differentiating AIP from PC. The sensitivity and specificity of IgG4 (cut-off 1.4 g/L) for differentiating AIP from PC was 45% and 88%, but rose to 52% and 88% when using a cut-off of 1.09 g/L. When using this cut-off, the sensitivity and specificity for differentiating type 1 AIP from PC was 68% and 88%. None of the other markers were significantly changed in AIP versus PC. For differentiation of type 1 and type 2 AIP, the only significant differences were IgG4 in type 1 AIP (P < .01), with a sensitivity of 68% and a specificity of 80%, and c-ANCA elevations found in some type 2 AIP patients (P < .05).The only serological marker for which we found a statistically significant difference in mean values between AIP and PC was IgG4. However, the value of IgG4 for the distinction of AIP from PC was limited, probably in part due to the relatively high number of type 2 AIP patients in our study. In accord with recent publications, our data do not support a role of increased serum a-PBP for the diagnosis of AIP.

High level of IgG4 as a biomarker for a new subset of inflammatory bowel disease

The roles of B and plasma cells in the pathogenesis of inflammatory bowel disease (IBD) are largely unrevealed. Data on the characteristics of IgG4 in patients with IBD are scarce. In this case-control study, serum IgG4 levels were comparable between patients with IBD and healthy individuals, whereas patients with IBD had dramatically higher mucosal IgG4 counts than healthy individuals. In patients with UC, mucosal IgG4 counts were positively correlated with serum IgG4 levels, serum IgG4/IgG ratios, and the Mayo Index; serum IgG4 levels and IgG4/IgG ratios were associated with a history of intestinal surgery and medications. A significant mucosal IgG4 count was found in 33.3% of patients with IBD, whereas, elevated serum IgG4 levels were found in only 9.9% of patients with IBD. Lesions were more severe and extensive in IBD patients with high levels of serum and mucosal IgG4. High levels of serum and mucosal IgG4 decreased after treatment with glucocorticoids or other immunosuppressants. High IgG4 level may be a biomarker for a new subset of IBD. More studies are warranted to explore this new subset of IBD for personalized therapy in the future.

Autoimmune Pancreatitis and Inflammatory Bowel Disease: An Updated Review

Autoimmune pancreatitis (AIP) occurring in association with inflammatory bowel disease (IBD) is rather rare and carries a worse prognosis and greater disease severity compared with IBD alone. Although it is an infrequently documented association, progress over the last 20 years has led to better understanding of the association between AIP and IBD. IBD has a stronger association with type 2 than with type 1 AIP. Clinical and histologic features of AIP-IBD more often reveal features of type 2 AIP. Imaging is not helpful in facilitating the diagnosis of AIP and IBD. Similarly, attempts to identify a serological marker have not yielded better result. A proposed lymphocyte homing mechanism provides some insight into the mechanism of pathogenesis. This review represents an update of our current knowledge of the association between AIP and IBD.

Recent developments in steroid-responsive pancreatitides (autoimmune pancreatitis)

PURPOSE OF REVIEW

There are two distinct steroid responsive chronic fibro-inflammatory diseases of the pancreas, called type 1 and type 2 autoimmune pancreatitis (AIP). We review recent progress in this field.

RECENT FINDINGS

It has recently been suggested that the term AIP be used to describe type 1 AIP and the term idiopathic duct-centric chronic pancreatitis (IDCP) be used for type 2 AIP. Clinical features and long-term outcomes of AIP and IDCP are well characterized and prognosis of both diseases is excellent. Diagnostic strategies tailored to regional practice patterns have emerged with the application of International Consensus Diagnostic Criteria for AIP. Although corticosteroids remain the mainstay of treatment, management of relapses and strategies for preventing multiple relapses are better understood, including the role of maintenance therapy and B-cell depletion therapy with rituximab. Association studies with malignancies have yielded conflicting results regarding risk of cancer in AIP.

SUMMARY

The treatment, follow-up guidelines and associations continue to evolve with our increasing experience with both AIP and IDCP. In AIP, rituximab can be used for both induction and maintenance of remission. IDCP responds to steroids without need for maintenance therapy. Both AIP and IDCP have excellent prognosis.

Prevalence and clinicopathological features of autoimmune pancreatitis in Japanese patients with inflammatory bowel disease

OBJECTIVES

The purpose of this study was to clarify the clinicopathological characteristics of autoimmune pancreatitis (AIP) in Japanese patients with inflammatory bowel disease (IBD).

METHODS

The clinicopathological findings of 7 patients with IBD whose definite AIP was diagnosed in our hospital according to the International Consensus Diagnostic Criteria were reviewed.

RESULTS

Five (0.5%) of 961 patients with ulcerative colitis (UC) and 2 (0.3%) of 790 patients with Crohn disease had AIP. All of 7 patients whose AIP was diagnosed were type 2. The rate of elevated values of serum immunoglobulin G4 was 0%. Most patients with the diagnosis of IBD preceded that of AIP, and disease activity of IBD were active. Granulocyte epithelial lesion is similar to the cryptitis seen in colonic tissue of UC. All of 7 patients were given corticosteroids, immunomodulators, and/or biological agents for IBD. One patient had a recurrence.

CONCLUSIONS

The frequency of AIP in Japanese patients with IBD was low. All cases were type 2 and responded well to corticosteroids, immunomodulators, and biological agents. Autoimmune pancreatitis in UC patients may be an extraintestinal manifestation of UC.

Comparison study of immunohistochemical staining for the diagnosis of type 1 autoimmune pancreatitis

BACKGROUND

Various methods to evaluate immunohistochemical staining (IHC) for the diagnosis of type 1 autoimmune pancreatitis (AIP) have been proposed. Our goal was to determine the most useful IHC method for the diagnosis of AIP.

METHODS

Specimens of AIP (18 patients), chronic pancreatitis (CP, 24 patients), and pancreatic ductal adenocarcinoma (PDA, 45 patients) were evaluated with IHC for immunoglobulin G (IgG), IgG1, IgG4, and CD138 (syndecan-1). The number of IHC-positive cells was counted in 3, 5, and 10 different high-power fields (HPFs) by selecting fields with the most numerous positive cells (hotspot) or by randomly selecting fields in the affected areas (random). We evaluated the mean number of IgG4-positive plasma cells (IgG4+)/HPF (mean IgG4+), the number of fields with >10 and >50 IgG4+ (NOF >10 and NOF >50 IgG4+), the ratio of IgG4+/IgG+, IgG4+/IgG1+, and IgG4+/CD138+.

RESULTS

Analysis with receiver operator characteristic curves revealed that accurate and practical parameters in 3 HPFs were mean IgG4+ with the hotspot method (sensitivity, 88.9; specificity, 92.8 %), mean IgG4+ with the random method (100, 95.7 %), and NOF >10 IgG4+ with the random method (94.4, 97.1 %). These results were as accurate as results from 5 HPFs to 10 HPFs. The combination of mean IgG4+ and IgG4+/IgG+ did not provide more accurate diagnosis for AIP than a single criterion itself.

CONCLUSIONS

Mean IgG4+ or NOF >10 IgG4+ with the random method in 3 HPFs was a useful and simple diagnostic method for AIP. The combined criteria of mean IgG4+ and IgG4+/IgG+ might not be required for accurate diagnosis of AIP.

Eosinophilic esophagitis in adults is associated with IgG4 and not mediated by IgE

BACKGROUND & AIMS

Eosinophilic esophagitis is usually triggered by foods, by unclear mechanisms. We evaluated the roles of IgE and IgG4 in the development of eosinophilic esophagitis.

METHODS

We performed a prospective, randomized, double-blind, placebo-controlled trial of adults with eosinophilic esophagitis given an antibody against IgE (omalizumab, n = 16) or placebo (n = 14) every 2-4 weeks for 16 weeks, based on weight and serum level of IgE. Endoscopy was performed, esophageal biopsy specimens were collected, and symptoms were assessed at baseline and at 16 weeks. Maximum numbers of eosinophils/high-power field were determined. Homogenates of esophageal biopsy specimens from 11 subjects with eosinophilic esophagitis and 8 without (controls) were assessed for IgM, IgA, and IgG subclasses. In a retrospective analysis, we performed immunofluorescence analysis of IgG4 in fixed esophageal tissues from 2 patients with eosinophilic esophagitis who underwent esophagectomy and 47 consecutive autopsies (controls). We also performed immunofluorescence analysis of IgG4 in esophageal mucosal biopsy specimens from 24 subjects with eosinophilic esophagitis and 9 without (controls). Finally, sera were collected from 15 subjects with eosinophilic esophagitis and from 41 without (controls), and assayed for total and food-reactive IgG4.

RESULTS

Omalizumab did not alter symptoms of eosinophilic esophagitis or eosinophil counts in biopsy samples compared with placebo. Homogenates of esophageal tissues from patients with eosinophilic esophagitis had a 45-fold increase in IgG4 compared with controls (P < 3 × 10(-5)), but no significant increases in other IgG subclasses, IgM, or IgA. Sparse stromal deposits resembling immune complexes were found in 2 of 5 eosinophilic esophagitis biopsy specimens based on ultrastructural analysis. Esophagectomy samples from 2 patients with eosinophilic esophagitis contained 180 and 300 IgG4 plasma cells/maximal high-power field, mainly in the deep lamina propria; these levels were greater than in tissues from controls. Fibrosis essentially was exclusive to the lamina propria. Granular extracellular IgG4 was detected in biopsy specimens from 21 of 24 patients with eosinophilic esophagitis, but in none of the specimens from 9 controls (P = 6 × 10(-6)). The total serum level of IgG4 increased only slightly in patients with eosinophilic esophagitis, compared with controls. Subjects with eosinophilic esophagitis had increased serum levels of IgG4 that reacted with milk, wheat, egg, and nuts-the 4 foods that most commonly trigger this condition (P ≤ 3 × 10(-4) for each food).

CONCLUSIONS

In a prospective trial, omalizumab did not reduce symptoms of eosinophilic esophagitis or tissue eosinophil counts compared with placebo. This finding, along with observed granular deposits of IgG4, abundant IgG4-containing plasma cells, and serum levels of IgG4 reactive to specific foods, indicate that, in adults, eosinophilic esophagitis is IgG4-associated, and not an IgE-induced allergy. ClinicalTrials.gov number: NCT 00123630.

A comparison of the diagnostic efficacy in type 1 autoimmune pancreatitis based on biopsy specimens from various organs

BACKGROUND

Comprehensive immunostaining evaluation of the biopsy specimens from various organs with type 1 autoimmune pancreatitis (AIP) has not been elucidated. Our aim was to clarify which of these biopsy specimens and counting method could be a useful tool for supporting the diagnosis of AIP.

METHODS

We retrospectively evaluated biopsy specimens from pancreas (n = 19), stomach (n = 28), duodenum (n = 27), duodenal papilla (n = 25), colon (n = 19), liver (n = 11), bile duct (n = 24), and minor salivary gland (n = 13) in 36 patients with AIP. Positive IgG4 immunostaining (>10 plasma cells/high-power field [HPF]) and positive IgG4/IgG ratio (>40%) of biopsy specimens from 8 sites of 6 organs in one HPF and an average from 3 HPFs were compared between AIP and controls.

RESULTS

The sensitivity of IgG4 immunostaining for AIP in one HPF were 16% in pancreas, 14% in stomach, 15% in duodenum, 52% in duodenal papilla, 11% in colon, 27% in liver, 21% in bile duct and 8% in minor salivary gland, respectively. The positive IgG4 immunostaining of the duodenal papilla in one HPF showed the highest sensitivity (52%) and accuracy (73%) among the 8 sites. It also showed the highest sensitivity among 4 different counting methods (IgG4 immunostaining in one HPF and 3 HPFs, both IgG4 immunostaining and IgG/IgG4 ratio in one HPF and 3 HPFs), but there were no significant differences with respect to specificity and accuracy.

CONCLUSIONS

IgG4 immunostaining of swollen duodenal papilla with more than 10 IgG4-positive plasma cells in at least one HPF is useful for supporting the diagnosis of AIP.

Ulcerative colitis and immunoglobulin G4

Background/Aims

Ulcerative colitis (UC) is sometimes associated with autoimmune pancreatitis (AIP). Infiltration of immunoglobulin G4 (IgG4)-positive plasma cells is sometimes detected in the colonic mucosa of AIP or UC patients. This study aimed to clarify the relation between UC and IgG4.

Methods

Associations with UC were reviewed in 85 AIP patients. IgG4 immunostaining was performed on biopsy specimens from the colonic mucosa of 14 AIP and 32 UC patients.

Results

UC was confirmed in two cases (type 1 AIP, n=1; suspected type 2 AIP, n=1). Abundant infiltration of IgG4-positive plasma cells in the colonic mucosa was detected in the case of suspected type 2 AIP with UC and two cases of type 1 AIP without colitis. Abundant infiltration of IgG4-positive plasma cells was detected in 10 UC cases (IgG4-present, 31%). Although 72% of IgG4-absent UC patients showed mild disease activity, 70% of IgG4-present patients showed moderate to severe disease activity (p<0.05).

Conclusions

UC is sometimes associated with AIP, but it seems that UC is not a manifestation of IgG4-related disease. Infiltration of IgG4-positive plasma cells is sometimes detectable in the colonic mucosa of UC patients and is associated with disease activity.

Immunoglobulin G4-related gastrointestinal diseases, are they immunoglobulin G4-related diseases?

In immunoglobulin G4 (IgG4)-related disease (RD), organ enlargement or nodular lesions consisting of abundant infiltration of lymphocytes and IgG4-positive plasma cells and fibrosis are seen in various organs. Although infiltration of many IgG4-positive plasma cells is detected in the gastric and colonic mucosa and major duodenal papilla of patients with autoimmune pancreatitis, it cannot be diagnosed as a gastrointestinal lesion involved in IgG4-RD, because none of the following is observed in these lesions: a mass-like formation; dense fibrosis; or obliterative phlebitis. Based on our review of the literature, there appear to be two types of IgG4-related gastrointestinal disease. One is a gastrointestinal lesion showing marked thickening of the wall of the esophagus and stomach, consisting of dense fibrosis with abundant infiltration of IgG4-positive plasma cells, which usually show submucosal spreading. The other is an IgG4-related pseudotumor occurring in gastrointestinal regions such as the stomach, colon, and major duodenal papilla, showing polypoid or mass-like lesions. Most solitary IgG4-related gastrointestinal lesions that are not associated with other IgG4-RD appear to be difficult to diagnose. It is of utmost importance to rule out malignancy. However, these lesions may respond to steroid therapy. To avoid unnecessary resection, IgG4-related gastrointestinal diseases should be considered in the differential diagnosis.

The successful treatment of IgG4-positive colitis with adalimumab in a patient with IgG4-related sclerosing disease--a new subtype of aggressive colitis?

We present the case of a 16 year old girl who developed an aggressive colitis in the context of a prior biopsy proven autoimmune pancreatitis, which presented with obstructive jaundice at the age of 13 year. This history prompted prospective investigation and the discovery of compelling evidence to make a diagnosis of IgG4-related sclerosing disease with extra-pancreatic colonic involvement on the basis of raised serum IgG4 levels and a florid colonic IgG4 plasma cell infiltrate with over 20 IgG4 positive plasma cells/hpf. The colitis was resistant to conventional therapy but responded dramatically to treatment with the anti-TNFα monoclonal antibody, adalimumab. This is the first case to report both the effectiveness of adalimumab in treating IgG4 positive colitis in a patient with IgG4-related sclerosing disease, and to prospectively record resolution of an IgG4 positive colonic infiltrate with immunosuppression.

Chronic pancreatitis

PURPOSE OF REVIEW

We review important new clinical observations in chronic pancreatitis reported in 2011.

RECENT FINDINGS

Smoking increases the risk of nongallstone acute pancreatitis and the progression of acute pancreatitis to chronic pancreatitis. Binge drinking during Oktoberfest did not associate with increased hospital admissions for acute pancreatitis. The unfolded protein response is an adaptive mechanism to maintain pancreatic health in response to noxious stimuli such as alcohol. Onset of diabetes mellitus in chronic pancreatitis is likely due to progressive disease rather than individual variables. Insufficient pancreatic enzyme dosing is common for treatment of pancreatic steatorrhea; 90 000 United States Pharmacopeia units of lipase should be given with meals. Surgical drainage provides sustained, superior pain relief compared with endoscopic treatment in patients advanced chronic pancreatitis with a dilated main duct ± pancreatic stones. The central acting gabapentoid pregabalin affords a modest 12% pain reduction in patients with chronic pancreatitis but approximately 30% of patients have significant side effects.

SUMMARY

Patients with nongallstone-related acute pancreatitis or chronic pancreatitis of any cause should cease smoking. Results of this year's investigations further elucidated the pancreatic pathobiology due to alcohol, onset of diabetes mellitus in chronic pancreatitis, and the mechanisms and treatment of neuropathic pain in chronic pancreatitis.

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

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

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

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