Frequent and significant K-ras mutation in the pancreas, the bile duct, and the gallbladder in autoimmune pancreatitis

Management strategies for autoimmune pancreatitis

INTRODUCTION

Autoimmune pancreatitis (AIP) is a newly developed concept for a peculiar type of pancreatitis, and at present is recognized as a pancreatic lesion reflecting IgG4-related systemic disease. It is of utmost importance to differentiate AIP from pancreatic cancer to avoid unnecessary surgery.

AREAS COVERED

The current management strategies for AIP, including its clinical features, diagnostic criteria, clinical subtypes, steroid therapy and prognosis are discussed, based on our 66 AIP cases and papers searched in PubMed from 1992 to March 2011, using the term 'autoimmune pancreatitis'. A new clinicopathological entity, an 'IgG4-related sclerosing disease' is also mentioned.

EXPERT OPINION

AIP should be considered in the differential diagnosis in elderly male patients presented with obstructive jaundice and pancreatic mass. Steroids are a standard therapy for AIP, but their regimen including maintenance therapy should be evaluated in prospective trials.

A novel polymorphism in codon 25 of the KRAS gene associated with gallbladder carcinoma patients of the eastern part of India

Gallbladder cancer (GBC) is more prevalent than other cancers in North India. The asymptomatic nature of the disease is a problem in the diagnosis and treatment. Analysis of oncogenes or tumor suppressor genes could be of importance in this regard. KRAS is the most frequently mutated member and is said to be one of the most activated oncogenes. The present study was aimed to determine the role of intragenic variants in the KRAS gene, in the progression of GBC in the eastern part of India. Sixty gallbladder carcinoma subjects (13 men and 47 women) with histologically proven diagnosis and 90 individuals (14 men and 76 women) who have no diagnosed cancer were included in the present study. All single-nucleotide polymorphisms present in exons 1 and 2 were analyzed by polymerase chain reaction followed by sequencing. We could not find the most frequently reported mutations at codons 12, 13, and 61 of the KRAS gene that occur in human malignancies. However, in this study, we detected one novel polymorphism at codon 25 (CAG>CAT; Gln25His) in exon 1 of the KRAS gene in both germline and tissue DNA. Multivariable logistic regression analysis with adjustment for age and sex revealed that the Gln25His variant of the KRAS gene was significantly associated with GBC. In silico analysis has validated the KRAS p.Q25H polymorphism as a disease-causing variant. Further, screening of the DNA samples in a cohort of ancestral tribal populations from various parts of the country without information on the phenotype, however, revealed the presence of the previously reported codon 12 and 25 polymorphisms, thereby indicating that the novel variant is population specific in the region.

Autoimmune pancreatitis and IgG4-related sclerosing cholangitis

PURPOSE OF REVIEW

Autoimmune pancreatitis (AIP) is a peculiar type of pancreatitis with a presumed autoimmune etiology. AIP is frequently associated with stenosis of the bile duct in the form of IgG4-related sclerosing cholangitis. This article reviews recent advances in clinicopathological findings for AIP and IgG4-related sclerosing cholangitis.

RECENT FINDINGS

AIP is currently diagnosed based on characteristic radiological findings (irregular narrowing of the main pancreatic duct and enlargement of the pancreas) in combination with serological findings (elevated serum IgG4 and presence of autoantibodies) and histopathological findings (dense infiltration of IgG4-positive plasma cells and lymphocytes with fibrosis and obliterative phlebitis in the pancreas). Other clinical characteristics include preponderance toward elderly men, common initial symptoms of obstructive jaundice, and favorable response to steroid therapy. Differentiation of AIP from pancreatic cancer is crucial. As AIP is frequently associated with various sclerosing extrapancreatic lesions showing the same peculiar histological findings seen in the pancreas, AIP is currently considered to represent a pancreatic manifestation of IgG4-related sclerosing disease. Considering the age of onset, associated diseases, cholangiography, serum IgG4 levels, and steroid responsiveness, IgG4-related sclerosing cholangitis differs from primary sclerosing cholangitis.

SUMMARY

AIP and associated extrapancreatic lesions are considered to represent clinical manifestations of IgG4-related sclerosing disease.

Autoimmune pancreatitis complicated by carcinoma of the pancreatobiliary system: a case report and review of the literature

We present the case of a 67-year-old woman who developed a metastatic adenocarcinoma of the pancreatobiliary system shortly after the histologically confirmed diagnosis of autoimmune pancreatitis (AIP). This case highlights the need for increased alertness not only in differentiating AIP from pancreatic cancer at the time of diagnosis, but also to exclude concomitant malignancies of the pancreatobiliary system in the management of histologically confirmed AIP.

Comparison of KRAS mutation analysis and FISH for detecting pancreatobiliary tract cancer in cytology specimens collected during endoscopic retrograde cholangiopancreatography

Pancreatobiliary tract strictures result either from malignancies of the biliary tract and pancreas or from nonmalignant etiopathogenesis. The goal of this study was to determine whether KRAS mutations could be identified in residual pancreatobiliary stricture brushings and to compare the performance characteristics of KRAS mutation analysis to cytology and fluorescence in situ hybridization (FISH) for the detection of carcinoma. Residual brushing cytology cell pellets were retrieved from 132 patients with subsequent clinicopathologic follow-up of cholangiocarcinoma (n = 41), pancreatic adenocarcinoma (n = 35), gallbladder cancer (n = 2), and nonmalignant strictures (n = 54). All specimens had a prior cytology and FISH UroVysion results as part of clinical practice. KRAS mutation analysis was performed using the quantitative PCR DxS KRAS Mutation Test Kit. KRAS mutation analysis was successful in 130 of 132 specimens. KRAS mutations and polysomic (ie, positive) FISH results were identified in 24 (69%) and 22 (63%) pancreatic adenocarcinoma specimens, respectively, with a combined sensitivity of 86% (30/35). KRAS mutations and polysomic FISH results were identified in 12 (29%) and 17 (41%) cholangiocarcinoma specimens, with a combined sensitivity of 54% (22/41). KRAS mutations were identified in two patients with primary sclerosing cholangitis, and benign follow-up. Residual cytology specimens can be used to detect KRAS mutations by quantitative PCR. Combined KRAS mutation and FISH analysis appear to increase the cancer detection rate in patients with pancreatobiliary strictures.

Autoimmune pancreatitis and IgG4-related sclerosing disease

Autoimmune pancreatitis (AIP) is a unique form of pancreatitis in which the pathogenesis is suspected to involve autoimmune mechanisms. AIP sometimes mimics pancreatic cancer in its presentation, but as AIP responds dramatically to steroid therapy, accurate diagnosis is necessary. AIP is currently diagnosed on the basis of a combination of characteristic clinical, serological, morphological and histopathological features. However, its diagnosis remains a clinical challenge and there are no internationally agreed diagnostic criteria. Another type of AIP called 'idiopathic duct-centric chronic pancreatitis' or 'AIP with granulocytic epithelial lesion' has been reported in Western countries. IgG4-related sclerosing disease is a systemic disease in which IgG4-positive plasma cells and T lymphocytes extensively infiltrate various organs. Organs with tissue fibrosis and obliterative phlebitis, such as the pancreas, salivary gland and retroperitoneum, show clinical manifestations; AIP seems to represent one manifestation of IgG4-related sclerosing disease. As a mass is formed in most cases of IgG4-related sclerosing disease, a malignant tumor is frequently suspected on initial presentation. Clinicians should consider IgG4-related sclerosing disease in the differential diagnosis to avoid unnecessary surgery.

K-ras mutation in the major duodenal papilla and gastric and colonic mucosa in patients with autoimmune pancreatitis

BACKGROUND

Pancreatic cancer occurs in some patients with autoimmune pancreatitis (AIP). Significant K-ras mutations are frequently detected in the pancreas of AIP patients. AIP may be a pancreatic lesion of IgG4-related systemic disease. Gastric and colonic cancer can occur during the follow up of AIP patients. We examined K-ras mutations in the major duodenal papilla and gastric and colonic mucosa of AIP patients.

METHODS

K-ras analysis and/or immunohistochemical study was performed on the tissues of the major duodenal papilla (n = 8), gastric mucosa (n = 5), colonic mucosa (n = 3), pancreas (n = 5), common bile duct (n = 5), and gallbladder (n = 4) of 12 AIP patients.

RESULTS

Significant K-ras mutations were detected in the major duodenal papilla of 4 of 8 cases [GAT (n = 4)], in the gastric mucosa of 2 of 4 cases [AGT (n = 2)], and in the colonic mucosa of 2 of 3 cases [GAT (n = 2)]. Significant K-ras mutations were detected in the pancreas of all 5 cases [GAT (n = 5), in the common bile duct of 4 cases (GAT (n = 2), TGT (n = 1), and GCT/TGT (n = 1)], and in the gallbladder epithelium of 3 cases [GAT (n = 1), GCT (n = 1), and GTT (n = 1)]. K-ras mutations were detected in the organs associated with IgG4-related fibroinflammation with abundant infiltration of T lymphocytes and forkhead box P3-positive cells.

CONCLUSIONS

Significant K-ras mutations were frequently detected in the major duodenal papilla and gastric and colonic mucosa of AIP patients. AIP patients may have risk factors for gastric and colonic cancer, but the mechanisms of K-ras mutation and its clinical implications are not clear.

Japanese consensus guidelines for management of autoimmune pancreatitis: III. Treatment and prognosis of AIP

Steroid therapy appeared to be a standard treatment for autoimmune pancreatitis (AIP), although some AIP patients improve spontaneously. The indications for steroid therapy in AIP patients are symptoms such as obstructive jaundice, abdominal pain, and back pain, and the presence of symptomatic extrapancreatic lesions. Before steroid therapy, jaundice should be managed by biliary drainage in patients with obstructive jaundice, and blood glucose levels should be controlled in patients with diabetes mellitus. For the initial oral prednisolone dose for induction of remission, 0.6 mg/kg/day is recommended. The initial dose is administered for 2-4 weeks, and the dose is tapered by 5 mg every 1-2 weeks, based on changes in the clinical manifestations, biochemical blood tests (such as liver enzymes and IgG or IgG4 levels), and repeated imaging findings (US, CT, MRCP, ERCP, etc.). The dose is tapered to a maintenance dose (2.5-5 mg/day) over a period of 2-3 months. Steroid therapy should be stopped based on the disease activity in each case. Stopping of maintenance therapy should be planned within at least 3 years in cases with radiological and serological improvement. Re-administration or dose-up of steroid is effective for treating AIP relapses. The prognosis of AIP appears to be good over the short-term with steroid therapy. It is unclear whether the long-term outcome is good because there are many unknown factors, such as relapse, pancreatic exocrine or endocrine dysfunction, and associated malignancy.