Clinical study of chronic pancreatitis with focal irregular narrowing of the main pancreatic duct and mass formation: comparison with chronic pancreatitis showing diffuse irregular narrowing of the main pancreatic duct

Autoimmune pancreatitis: Biopsy interpretation and differential diagnosis

Autoimmune pancreatitis (AIP) is classified into type 1 (IgG4-related) and type 2 (IgG4-unrelated) and the interpretation of pancreatic biopsy findings plays a crucial role in their diagnosis. Needle biopsy of type 1 AIP in the acute or subacute phase shows a diffuse lymphoplasmacytic infiltrate, storiform fibrosis, obliterative phlebitis, and the infiltration of many IgG4-positive plasma cells. In a later phase, changes become less inflammatory and more fibrotic, making interpretations more challenging. Confirmation of the lack of 'negative' findings that are unlikely to occur in type 1 AIP (e.g., neutrophilic infiltration, abscess) is important to avoid an overdiagnosis. The number of IgG4-positive plasma cells increases to >10 cells/high-power field (hpf), and the IgG4/IgG-positive plasma cell ratio exceeds 40 %. However, these are minimal criteria and typical cases show >30 positive cells/hpf and a ratio >70 % even in biopsy specimens. Therefore, cases with a borderline increase in this number or ratio need to be diagnosed with caution. In cases of ductal adenocarcinoma, the upstream pancreas rarely shows type 1 AIP-like changes; however, the ratio of IgG4/IgG-positive plasma cells is typically <40 %. Although the identification of a granulocytic epithelial lesion (GEL) is crucial for type 2 AIP, this finding needs to be interpreted in conjunction with a background dense lymphoplasmacytic infiltrate. An isolated neutrophilic duct injury can occur in peritumoral or obstructive pancreatitis. Drug-induced pancreatitis in patients with inflammatory bowel disease often mimics type 2 AIP clinically and pathologically. IL-8 and PD-L1 are potential ancillary immunohistochemical markers for type 2 AIP, requiring validation studies.

Jaundice on Presentation Is Associated with Higher In-Patient Mortality and Complications in Patients Admitted for Acute Pancreatitis: A Retrospective Study Based on National Inpatient Sample Database

Pancreatitis usually presents with characteristic abdominal pain, radiological findings, and elevated lipase. The presence of jaundice may hint at a biliary etiology; however, it is not always present. We hypothesized that the presence of jaundice is associated with worse outcomes in patients admitted with pancreatitis. We conducted a retrospective analysis using the National Inpatient Sample, inquiring about patients admitted with pancreatitis with and without jaundice between October 2015 and December 2017. The primary outcome was in-hospital mortality in patients admitted for pancreatitis with and without jaundice. Secondary outcomes were the median length of stay, hospitalization cost, the incidence of ventilator-dependent respiratory failure (VDRF), acute respiratory distress syndrome (ARDS), sepsis, septic shock, dehydration and electrolyte disturbances, and ascites. A total of 1,267,744 patients were admitted with pancreatitis from October 2015 to December 2017. Among them, 8855 (0.7%) had concomitant jaundice on presentation. In-hospital mortality in this group was 4.3%. The patients with pancreatitis and jaundice had higher odds of in-hospital mortality (adjusted odds ratio [aOR]: 1.51, 99% CI 1.35–1.68, p < 0.0001) as compared to those without jaundice. Patients with jaundice showed a significantly higher incidence of sepsis (15.2% vs. 9.6%, p < 0.0001), septic shock (4.1% vs. 2.9%, p < 0.0001), ascites (6.5% vs. 3.1%, p < 0.0001), and dehydration and electrolyte disorders (47.6% vs. 43.8%, p < 0.0001). Patients with jaundice also had higher total hospital costs ($11,412 vs. $7893, p < 0.0001). There was no statistical difference in ARDS, VDRF, and median length of stay. In conclusion, patients admitted for pancreatitis with jaundice had worse outcomes, including in-hospital mortality and complications, compared to those without jaundice.

Coexisting Type 1 Autoimmune Pancreatitis and Mixed-type Intraductal Papillary Mucinous Neoplasm

An 84-year-old man was referred to our hospital for a cystic lesion of the pancreatic head, swelling of the pancreatic tail and hilar biliary stricture, resulting in elevated liver enzyme levels. We suspected branch duct-type intraductal papillary mucinous neoplasm (IPMN) and type I autoimmune pancreatitis (AIP) associated with sclerosing cholangitis because of the high serum IgG4 levels. The main pancreatic duct on the tail side of the AIP lesion was moderately dilated. Although the biliary stricture and pancreatic swelling improved after prednisolone treatment, the pancreatic enzyme levels increased rapidly. The entire main pancreatic duct exhibited remarkable dilatation, which led to the diagnosis of mixed-type IPMN. The clinical characteristics of IPMN in the main pancreatic duct appear to have been initially masked by AIP.

Multifocal autoimmune pancreatitis: A retrospective study in a single tertiary center of 26 patients with a 20-year literature review

BACKGROUND

Multifocal-type autoimmune pancreatitis (AIP), sometimes forming multiple pancreatic masses, is frequently misdiagnosed as pancreatic malignancy in routine clinical practice. It is critical to know the imaging features of multifocal-type AIP to prevent misdiagnosis and unnecessary surgery. To the best of our knowledge, there have been no studies evaluating the value of diffusionweighted imaging (DWI), axial fat-suppressed T1 weighted image (T1WI), and dynamic contrast enhanced-computed tomography (DCE-CT) in detecting the lesions of multifocal-type AIP.

AIM

To clarify the exact prevalence and radiological findings of multifocal AIP in our cohorts and compare the sensitivity of DWI, axial fat-suppressed T1WI, and DCE-CT for detecting AIP lesions. We also compared radiological features between multifocal AIP and pancreatic ductal adenocarcinoma with several key imaging landmarks.

METHODS

Twenty-six patients with proven multifocal AIP were retrospectively included. Two blinded independent radiologists rated their confidence level in detecting the lesions on a 5-point scale and assessed the diagnostic performance of DWI, axial fat-suppressed T1WI, and DCE-CT. CT and magnetic resonance imaging of multifocal AIP were systematically reviewed for typical imaging findings and compared with the key imaging features of pancreatic ductal adenocarcinoma.

RESULTS

Among 118 patients with AIP, 26 (22.0%) had multiple lesions (56 lesions). Ulcerative colitis was associated with multifocal AIP in 7.7% (2/26) of patients, and Crohn’s disease was present in 15.3% (4/26) of patients. In multifocal AIP, multiple lesions, delayed homogeneous enhancement, multifocal strictures of the main pancreatic duct, capsule-like rim, lower apparent diffusion coefficient values, and elevated serum Ig4 level were observed significantly more frequently than pancreatic ductal adenocarcinoma, whereas the presence of capsule-like rim in multifocal-type AIP was lower in frequency than total AIP. Of these lesions of multifocal AIP, DWI detected 89.3% (50/56) and 82.1% (46/56) by the senior and junior radiologist, respectively.

CONCLUSION

Multifocal AIP is not as rare as previously thought and was seen in 22.0% of our patients. The diagnostic performance of DWI for detecting multifocal AIP was best followed by axial fat-suppressed T1WI and DCE-CT.

Clinical Application of Metabolomics in Pancreatic Diseases: A Mini-Review

Metabolomics is a powerful new analytical method to describe the set of metabolites within cellular tissue and bodily fluids. Metabolomics can uncover detailed information about metabolic changes in organisms. The morphology of these metabolites represents the metabolic processes that occur in cells, such as anabolism, catabolism, inhomogeneous natural absorption and metabolism, detoxification, and metabolism of biomass energy. Because the metabolites of different diseases are different, the specificity of the changes can be found by metabolomics testing, which provides a new source of biomarkers for the early identification of diseases and the difference between benign and malignant states. Metabolomics has a wide application potential in pancreatic diseases, including early detection, diagnosis, and identification of pancreatic diseases. However, there are few studies on metabolomics in pancreatic diseases in the literature. This article reviews the application of metabolomics in the diagnosis, prognosis, treatment, and evaluation of pancreatic diseases.

MR Imaging of Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is characterized by autoimmune inflammatory destruction of the pancreatic tissue. Imaging plays an essential role in the diagnosis. AIP type 1 is the pancreatic manifestation of immunoglobulin G4 (IgG4)-related disease and is associated with IgG4-positive plasma cell infiltration and fibrosis of multiple organ systems. Type 2 is a related disease with pancreatic inflammation with or without concurrent inflammatory bowel disease. The authors demonstrate the imaging findings that are associated with the pancreatic and extra-pancreatic manifestations of AIP. They emphasize the common MR imaging and magnetic resonance cholangiopancreatography findings to help make the diagnosis of AIP.

Analysis of metabolic characteristics in a rat model of chronic pancreatitis using high-resolution magic-angle spinning nuclear magnetic resonance spectroscopy

Pathological and metabolic alterations co-exist and co-develop in the progression of chronic pancreatitis (CP). The aim of the present study was to investigate the metabolic characteristics and disease severity of a rat model of CP in order to determine associations in the observed pathology and the metabolites of CP using high-resolution magic-angle spinning nuclear magnetic resonance spectroscopy (HR-MAS NMR). Wistar rats (n=36) were randomly assigned into 6 groups (n=6 per group). CP was established by administering dibutyltin dichloride solution into the tail vein. After 0, 7, 14, 21, 28 and 35 days, the pancreatic tissues were collected for pathological scoring or for HR-MAS NMR. Correlation analyses between the major pathological scores and the integral areas of the major metabolites were determined. The most representative metabolites, aspartate, betaine and fatty acids, were identified as possessing the greatest discriminatory significance. The Spearman’s rank correlation coefficients between the pathology and metabolites of the pancreatic tissues were as follows: Betaine and fibrosis, 0.454 (P=0.044); betaine and inflammatory cell infiltration, 0.716 (P=0.0001); aspartate and fibrosis, −0.768 (P=0.0001); aspartate and inflammatory cell infiltration, −0.394 (P=0.085); fatty acid and fibrosis, −0.764 (P=0.0001); and fatty acid and inflammatory cell infiltration, −0.619 (P=0.004). The metabolite betaine positively correlated with fibrosis and inflammatory cell infiltration in CP. In addition, aspartate negatively correlated with fibrosis, but exhibited no significant correlation with inflammatory cell infiltration. Furthermore, the presence of fatty acids negatively correlated with fibrosis and inflammatory cell infiltration in CP. HR-MAS NMR may be used to analyze metabolic characteristics in a rat model of different degrees of chronic pancreatitis.

Autoimmune pancreatitis: multidetector-row computed tomography (MDCT) and magnetic resonance (MR) findings in the Italian experience

Multidetector-row computed tomography (MDCT) and magnetic resonance (MR) imaging are currently the most frequently performed imaging modalities for the study of pancreatic disease. In cases of suspected autoimmune pancreatitis (AIP), a dynamic quadriphasic (precontrast, contrast-enhanced pancreatic, venous and late phases) study is recommended in both techniques. In the diffuse form of autoimmune pancreatitis (DAIP), the pancreatic parenchyma shows diffuse enlargement and appears, during the MDCT and MR contrast-enhanced pancreatic phase, diffusely hypodense and hypointense, respectively, compared to the spleen because of lymphoplasmacytic infiltration and pancreatic fibrosis. During the venous phase of MDCT and MR imaging, the parenchyma appears hyperdense and hyperintense, respectively, in comparison to the pancreatic phase. In the delayed phase of both imaging modalities, it shows retention of contrast media. A "capsule-like rim" may be recognised as a peripancreatic MDCT hyperdense and MR hypointense halo in the T2-weighted images, compared to the parenchyma. DAIP must be differentiated from non-necrotizing acute pancreatitis (NNAP) and lymphoma since both diseases show diffuse enlargement of the pancreatic parenchyma. The differential diagnosis is clinically difficult, and dynamic contrast-enhanced MDCT has an important role. In the focal form of autoimmune pancreatitis (FAIP), the parenchyma shows segmental enlargement involving the head, the body-tail or the tail, with the same contrast pattern as the diffuse form on both modalities. FAIP needs to be differentiated from pancreatic adenocarcinoma to avoid unnecessary surgical procedures, since both diseases have similar clinical and imaging presentation. The differential diagnosis is clinically difficult, and dynamic contrast-enhanced MDCT and MR imaging both have an important role. MR cholangiopancreatography helps in the differential diagnosis. Furthermore, MDCT and MR imaging can identify the extrapancreatic manifestations of AIP, most commonly biliary, renal and retroperitoneal. Finally, in all cases of uncertain diagnosis, MDCT and/or MR follow-up after short-term treatment (2-3 weeks) with high-dose steroids can identify a significant reduction in size of the pancreatic parenchyma and, in FAIP, normalisation of the calibre of the upstream main pancreatic duct.

Should Steroid Therapy Be Necessarily Needed for Autoimmune Pancreatitis Patients with Lesion Resected due to Misdiagnosed or Suspected Malignancy?

To explore whether steroid therapy should be needed for autoimmune pancreatitis patients after operation, eight AIP patients receiving operation were enrolled in this study from January 2007 to July 2013. All patients underwent liver function, CA19-9, and contrast-enhanced CT and/or MRI. Tests of IgG and IgG4 were performed in some patients. Tests of serum TB/DB, γ -GT, and γ -globulin were undergone during the perioperative period. Six cases receiving resection were pathologically confirmed as AIP patients and two were confirmed by intraoperative biopsy. For seven patients, TB/DB level was transiently elevated 1 day or 4 days after operation but dropped below preoperative levels or to normal levels 7 days after operation, and serum γ -GT level presented a downward trend. Serum γ -globulin level exhibited a downward trend among six AIP patients after resection, while an upward trend was found in another two AIP patients receiving internal drainage. Steroid therapy was not given to all six AIP patients until two of them showed new lines of evidence of residual or extrapancreatic AIP lesion after operation, while another two cases without resection received steroid medication. Steroid therapy might not be recommended unless there are new lines of evidence of residual extrapancreatic AIP lesions after resection.

Analysis of risk factors for pancreatic duct stones formation in patients with alcoholic chronic pancreatitis

BACKGROUND

Alcoholic chronic pancreatitis (ACP) is the dominant cause of chronic pancreatitis (CP). As a main complication of CP, the formation of pancreatic duct stones (PDS) compromises pancreatic function and symptomatic patients are often subjected to aggressive treatments. The present study aimed to identify PDS risk factors in patients with ACP.

METHODS

A retrospective analysis of 93 ACP patients was performed; patients were divided into two groups: ACP with PDS (n = 48) and ACP without PDS (n = 45). Fourteen potential factors were analyzed by univariate and multivariate analyses to identify independent risk factors of PDS formation in ACP patients. A comparison of demographic and clinical characteristics between ACP patients with PDS and non-ACP patients with PDS (n = 43) was also carried out.

RESULTS

ACP accounted for 47.7% (93/195) of CP in this cohort. Among ACP patients, the morbidity of PDS was 51.6% (48/93). Significant risk factors of PDS formation for ACP patients included duration of drinking ≥24.7 years (OR, 9.036; 95% CI, 2.737-29.837; p < 0.001); daily alcohol consumption ≥147.0 g (OR, 3.147; 95% CI, 1.040-9.522; p = 0.042); and MPD narrowing (OR, 7.245; 95% CI, 2.205-23.811; p = 0.001). Shorter periods between diagnosis and PDS formation (PDP) were observed in ACP patients than non-ACP patients.

CONCLUSIONS

Alcohol consumption accelerates the progression of PDS formation in patients with CP.

Clinical strategies for differentiating autoimmune pancreatitis from pancreatic malignancy to avoid unnecessary surgical resection

OBJECTIVE

The study aimed to determine a practical strategy for differentiating between autoimmune pancreatitis (AIP) and pancreatic malignancy in order to avoid unnecessary surgical resection.

METHODS

Altogether, 19 patients with AIP or other pancreatic diseases underwent routine examinations including liver function test and carbohydrate antigen 19-9, computed tomography and/or magnetic resonance imaging. Serum immunoglobulin G (IgG) and/or IgG4 was determined in patients with clinically suspected or pathologically proven AIP. Patients with suspected AIP either received diagnostic steroid therapy or laparotomy (if malignant tumors could not be excluded). Surgery was not performed in patients with a definite diagnosis of AIP by fast intraoperative frozen biopsy. Those with confirmed AIP received steroid treatment.

RESULTS

In total, 15 cases were finally confirmed as AIP with eight diagnosed preoperatively, five confirmed by surgical pathology (preoperatively misdiagnosed) and two by intraoperative biopsy. Of these 15 patients with AIP and one without AIP, 14 had elevated serum γ-globulin levels. It was proven by subsequent antibody tests that serum IgG or IgG4 were simultaneously increased.

CONCLUSIONS

Elevated serum γ-globulin level can be used as a preoperative sentinel indicator for differentiating between IgG4-related AIP and pancreatic malignancy. Serum IgG or IgG4 tests should be further performed in those with elevated serum γ-globulin level, which helps to identify AIP in order to avoid unnecessary operation.

Autoimmune pancreatitis and non-necrotizing acute pancreatitis: computed tomography pattern

OBJECTIVES

To retrospectively differentiate diffuse autoimmune pancreatitis from non-necrotizing acute pancreatitis at clinical onset with multi detector row computed tomography.

METHODS

36 Patients suffering from diffuse autoimmune pancreatitis (14) or non-necrotizing acute pancreatitis (22) were enrolled. Qualitative analysis included stranding, retroperitoneal fluid film, capsule-like rim enhancement and pleural effusion. In quantitative analysis pancreatic density was measured in all phases. The vascularization behaviour was assessed using the relative enhancement rate across all phases.

RESULTS

Pancreatic density resulted lower in non-necrotizing acute pancreatitis compared to diffuse autoimmune pancreatitis patients in pre-contrast phase and higher in pancreatic phase. Relative enhancement rate evaluation confirmed different vascularization behaviours of the two diseases. Only non-necrotizing acute pancreatitis Patients presented peripancreatic stranding and fluid in the retromesenteric interfascial plane.

CONCLUSIONS

Multi detector row computed tomography is a useful technique for differentiating diffuse autoimmune pancreatitis from non-necrotizing acute pancreatitis at clinical onset. Peripancreatic stranding and retroperitoneal fluid film, characteristic of non-necrotizing acute pancreatitis, and late-phase peripheral rim enhancement, characteristic of diffuse autoimmune pancreatitis, provide qualitative clues to the differentiation. A quantitative study of contrast enhancement patterns, considering the relative enhancement rate, can assist in the differential diagnoses of two diseases.

Differences between diffuse and focal autoimmune pancreatitis

AIM: To investigate differences in clinical features between diffuse- and focal-type autoimmune pancreatitis (AIP).

METHODS: Based on radiological findings by computed tomography and/or magnetic resonance imaging, we divided 67 AIP patients into diffuse type (D type) and focal type (F type). We further divided F type into head type (H type) and body and/or tail type (B/T type) according to the location of enlargement. Finally, we classified the 67 AIP patients into three groups: D type, H type and B/T type. We compared the three types of AIP in terms of clinical, laboratory, radiological, functional and histological findings and clinical course.

RESULTS: There were 34 patients with D-type, 19 with H-type and 14 with B/T-type AIP. Although obstructive jaundice was frequently detected in D-type patients (88%) and H-type patients (68%), no B/T-type patients showed jaundice as an initial symptom (P < 0.001). There were no differences in frequency of abdominal pain, but acute pancreatitis was associated more frequently in B/T-type patients (36%) than in D-type patients (3%) (P = 0.017). Serum immunoglobulin G (IgG)4 levels were significantly higher in D-type patients (median 309 mg/dL) than in B/T-type patients (133.5 mg/dL) (P = 0.042). Serum amylase levels in B/T-type patients (median: 114 IU/L) were significantly greater than in H-type patients (72 IU/L) (P = 0.049). Lymphoplasmacytic sclerosing pancreatitis (LPSP) was histologically confirmed in 6 D-type, 7 H-type and 4 B/T-type patients; idiopathic duct-centric pancreatitis was observed in no patients. Marked fibrosis and abundant infiltration of CD20-positive B lymphocytes with few IgG4-positive plasma cells were detected in 2 B/T-type patients. Steroid therapy was effective in all 50 patients (31 D type, 13 H type and 6 B/T type). Although AIP relapsed during tapering or after stopping steroids in 3 D-type and 3 H-type patients, no patients relapsed in B/T type. During follow-up, radiological features of 6 B/T-type patients were not changed and 1 B/T-type patient improved naturally.

CONCLUSION: Clinical features of H-type AIP were similar to those of D-type, but B/T-type differed from D and H types. B/T-type may involve diseases other than LPSP.

Mass-forming autoimmune pancreatitis and pancreatic carcinoma: differential diagnosis on the basis of computed tomography and magnetic resonance cholangiopancreatography, and diffusion-weighted imaging findings

PURPOSE

To differentiate mass-forming autoimmune pancreatitis (AIP) from pancreatic carcinoma by means of analysis of both computed tomography (CT) and magnetic resonance imaging (MRI) findings.

MATERIALS AND METHODS

Ten patients with mass-forming AIP diagnosed by revised clinical criteria of Japan Pancreas Society and 70 patients with pathologically proven pancreatic carcinoma were enrolled in this retrospective study. Two radiologists independently evaluated the CT and MR imaging findings. The sensitivity, specificity, and odds ratio of significant imaging findings and combinations of findings were calculated.

RESULTS

Seven findings were more frequently observed in AIP patients: (i) early homogeneous good enhancement, (ii) delayed homogeneous good enhancement, (iii) hypoattenuating capsule-like rim, (iv) absence of distal pancreatic atrophy, (v5) duct penetrating sign, (vi) main pancreatic duct (MPD) upstream dilatation ≤ 4 mm, and (vii) an apparent diffusion coefficient (ADC) ≤ 0.88 × 10(-3) mm(2) /s. When the findings of delayed homogeneous enhancement and ADC ≤ 0.88 × 10(-3) mm(2) /s were both used in diagnosis of mass-forming AIP, a sensitivity of 100% and a specificity of 100% were achieved. When 4 of any of the 7 findings were used in the diagnosis of AIP, a sensitivity of 100% and a specificity of 98% were achieved.

CONCLUSION

Analysis of a combination of CT and MR imaging findings allows for highly accurate differentiation between mass-forming AIP and pancreatic carcinoma.

Therapeutic management and clinical outcome of autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis, in comparison to other benign chronic pancreatic diseases, is characterized by the possibility of curing the illness with immunosuppressant drugs. The open question is whether to differentiate autoimmune pancreatitis as a primary or secondary disease based on the presence or absence of other autoimmune diseases or whether to consider autoimmune pancreatitis a clinical and pathological systemic entity, called IgG4-related sclerosing disease, since this aspect is also very important from a therapeutic point of view.

METHODS

In this paper, we reviewed the conventional therapeutic approach used to treat autoimmune pancreatitis patients and the clinical outcome related to each treatment modality. We also reviewed some aspects which are important for the correct management of autoimmune pancreatitis, such as the surgical approach, the outcome of surgically treated autoimmune pancreatitis patients, whether medical treatment is always necessary, and, finally, when medical treatment should be initiated.

CONCLUSIONS

Steroids are useful in alleviating the symptoms of the acute presentation of autoimmune pancreatitis, but some questions remain open such as the dosage of steroids in the acute phase and the duration of steroid therapy; finally, it should be assessed if other immunosuppressive non-steroidal drugs may become the first-line therapy in patients with AIP without jaundice and without atrophic pancreas.

Autoimmune pancreatitis mimicking pancreatic cancer

BACKGROUND/PURPOSE

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that can often be difficult to distinguish from pancreatic cancer. We describe the clinical and radiographic features of 23 patients with AIP whose presentations mimicked pancreatic cancer.

METHODS

A review of clinic, radiology, and endoscopy records from a 6-year period identified patients with AIP initially suspected of having pancreatic cancer. Abdominal computed tomography (CT) with intravenous contrast, endoscopic ultrasonography (EUS), and/or ERCP was performed in each patient. The diagnosis of AIP was made histologically and/or cytologically for each patient.

RESULTS

Nineteen of 23 patients (83%) presented with new-onset weight loss, jaundice, or both. Nineteen (83%) patients had CT findings worrisome for pancreatic cancer including: (1) pancreatic enlargement or focal mass, (2) regional lymphadenopathy, and/or (3) vascular invasion. Eighteen patients (78%) had common bile duct strictures on ERCP. EUS-guided fine-needle aspiration biopsies excluded pancreatic cancer in all 22 patients who had EUS (96%). Seven patients had surgery for continued suspicion of pancreatic cancer.

CONCLUSIONS

Although AIP commonly presents with features suggestive of pancreatic cancer, clinical recognition of AIP with appropriate diagnostic testing including EUS with fine-needle aspiration, ERCP, IgG4 levels, and pancreatic protocol CT expedites diagnosis and can spare patients unnecessary surgery.

Small nodules which could indicate the early phase of autoimmune pancreatitis

We present a case with small pancreatic nodules, which could indicate the early phase of autoimmune pancreatitis (AIP). A 68-year-old man was referred to our hospital for further diagnostic evaluation of a pancreatic mass detected on abdominal ultrasonography screening for epigastric discomfort. Abdominal ultrasonography and endoscopic ultrasonography revealed a low echoic lesion measuring approximately 1 cm with an irregular margin in the body of the pancreas. Computed tomography revealed a tumor in the portal venous phase of enhancement; hence, a distal pancreatectomy was performed. On histology, a marked lymphocyte- and plasma cell-dominant inflammatory cell infiltrate was observed in the nodule. There was another smaller nodule consisting of moderate lymphoplasmacytic infiltration in the 2-cm distal portion of the pancreas. Lymphoplasmacytic infiltration was also observed around the main pancreatic duct in the pancreatic stump. In the parenchyma, other than these 3 portions, the normal lobular structure was well preserved. Little storiform fibrosis and obliterative phlebitis were observed in the resected specimen. On immunohistochemical staining, plasma cells showing strong immunoreactivity for immunoglobulin G4 were observed within these two nodules and around the main pancreatic duct at the cut surface. This case could indicate the early phase and multicentricity of AIP.

Autoimmune pancreatitis

Autoimmune pancreatitis is becoming a more widely recognized form of pancreatitis that can mimic pancreatic or biliary malignancy. The combination of serological, histological and radiographic findings makes it unique among pancreatic diseases. The presence of autoantibodies, IgG4 and a lymphoplasmacytic infiltrate reflect its autoimmune etiology. The dramatic response to steroids is also a distinguishing feature and differentiates it from other pancreatic diseases.

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.

The clinical and radiological characteristics of focal mass-forming autoimmune pancreatitis: comparison with chronic pancreatitis and pancreatic cancer

OBJECTIVES

We investigated the clinical and radiological features of focal mass-forming autoimmune pancreatitis (FMF AIP) to help physicians avoid performing unnecessary surgery because of an improper diagnosis.

METHODS

We evaluated 23 patients with chronic inflammatory pancreatic masses and who underwent pancreatectomy for presumed pancreatic cancer from April 1995 to December 2005. These patients were distinguished into 8 FMF AIP patients and 15 ordinary chronic pancreatitis patients through a histological review, along with considering the immunoglobulin G4 staining. Twenty-six randomly selected pancreatic cancer patients were also evaluated as a control group.

RESULTS

On the portal venous phase of computed tomography, 6 (85.7%) of 7 FMF AIP patients showed homogeneous enhancement, whereas only 3 chronic pancreatitis patients (25%) and none of the pancreatic cancer patients showed homogeneous enhancement (P < 0.001). None of the FMF AIP patients showed upstream main pancreatic duct dilatation greater than 5 mm or proximal pancreatic atrophy.

CONCLUSIONS

For patients with a pancreatic mass, if their radiological images show homogeneous enhancement on the portal venous phase, the absence of significant upstream main pancreatic duct dilatation greater than 5 mm, and the absence of proximal pancreatic atrophy, then conducting further evaluations should be considered to avoid performing unnecessary surgery.

Normal pancreatic exocrine function does not exclude MRI/MRCP chronic pancreatitis findings

OBJECTIVE

Abnormal pancreatic function tests have been reported to precede the imaging findings of chronic pancreatitis. Magnetic resonance imaging (MRI) with magnetic resonance cholangiopancreatography (MRCP) is increasingly accepted as the primary imaging modality for the detection of structural changes of early mild chronic pancreatitis. The aim of this study was to evaluate MRI/MRCP findings in patients with symptoms consistent with chronic pancreatitis who have normal Secretin Endoscopic Pancreatic Function test.

METHODS

A retrospective study of 32 patients referred for evaluation of chronic abdominal pain consistent with chronic pancreatitis and reported normal standard abdominal imaging (ultrasound, computed tomography, or MRI). All patients underwent Secretin Endoscopic Pancreatic Function testing and pancreatic MRI/MRCP at our institution. We reviewed the MRI/MRCP images in patients who had normal Secretin Endoscopic Pancreatic Function testing. MRI/MRCP images were assessed for pancreatic duct morphology, gland size, parenchymal signal and morphology, and arterial contrast enhancement.

RESULTS

Of the 32 patients, 23 had normal Secretin Endoscopic Pancreatic Function testing, and 8 of them had mild to marked spectrum of abnormal MRI/MRCP findings that were predominantly focal. Frequencies of the findings were as follows: pancreatic duct stricture (n=3), pancreatic duct dilatation (n=3), side branch ectasia (n=4), atrophy (n=5), decreased arterial enhancement (n=5), decreased parenchymal signal (n=1), and cavity formation (n=1). The remaining15 patients had normal pancreatic structure on MRI/MRCP.

CONCLUSIONS

Normal pancreatic function testing cannot exclude abnormal MRI/MRCP especially focal findings of chronic pancreatitis. Further studies needed to verify significance of these findings and establish MRI/MRCP imaging criteria for the diagnosis of chronic pancreatitis.

Autoimmune pancreatitis with multifocal lesions

Two cases of a focal type of autoimmune pancreatitis (AIP) with distinct double mass lesions within the pancreas are described. In both patients, computed tomography (CT) showed localized pancreatic masses with delayed enhancement, and magnetic resonance cholangiopancreatography (MRCP) revealed localized stenoses of the main pancreatic duct (MPD) with mild upstream dilatation. Fluorodeoxyglucose positron emission tomography (FDG-PET) examination, performed in one patient, showed intense uptake concordant with tumors. Both patients received pancreatic resection with a presumptive diagnosis of pancreatic carcinoma. Histologic evaluation of the tumors showed marked lymphoplasmacytic infiltration and fibrosis around the large and medium pancreatic ducts, without any evidence of malignancy. Serum IgG4 concentration, measured postoperatively, was elevated in both patients. The characteristic morphological features of AIP are diffuse swelling of the pancreatic parenchyma and diffuse narrowing of the MPD. Recently, a focal type of AIP, which mimics pancreatic carcinoma, has been recognized. Considering the favorable response of AIP to steroid therapy, it is clinically important to differentiate the focal type of AIP from pancreatic carcinoma and to know that AIP sometimes exhibits multiple lesions within the pancreas.

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.

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.

Autoimmune chronic pancreatitis

BACKGROUND

Autoimmune pancreatitis (AIP) is a unique form of chronic pancreatitis that is characterized by swelling of the pancreas, narrowing of the main pancreatic duct (MPD), elevation of serum gamma globulin, or immunoglobulin G or presence of autoantibody, lymphoplasmacytic infiltration and dense fibrosis on histopathology. It is responsive to steroid therapy. The incidence of AIP can reach 5-6% of chronic pancreatitis. It can present as obstructive jaundice, body weight loss, and pancreas head mass mimicking pancreatic cancer. The recognition of AIP can avoid major surgery such as pancreatic resection.

METHODS

From May 2003 to July 2007, a total of 5 cases of AIP were reviewed retrospectively. The diagnosis was made on imaging study, serology, steroid response and/or histology if surgery was carried out.

RESULTS

There were 2 male and 3 female patients, with a mean age of 61 (39-75) years. Atypical AIP was found in the first case and typical AIP in the remaining 4. The presenting clinical pictures were mild epigastric pain, obstructive jaundice, and loss of body weight in 4 cases, with associated autoimmune disease in 1. Diffuse or long segmental enlargement of the pancreas without peripancreatic fat infiltration was found in all patients except 1 who only had focal pancreatic head enlargement. Distal common bile duct (CBD) stricture was seen in 4 cases and the median CBD stricture length was 1.2 (0.5-2.5) cm. Multiple narrowing of the whole MPD was seen in 2 cases, focal narrowing of the MPD in 2 and long segmental narrowing of the MPD in 1. Serum immunoglobulin G tests were done in 4 cases and were elevated in all. Antinuclear antibody was positive in 3. The first case was operated on after a preoperative diagnosis of suspicious pancreatic head tumor. The subsequent 3 cases were diagnosed correctly as AIP. The last case presented with distal CBD stricture and hypoechoic lesion in the pancreas head on endoscopic ultrasound, with only borderline pancreatic enlargement on computed tomography, and he was operated on. Retrospective endoscopic retrograde pancreatogram review revealed MPD narrowing in the pancreatic body. Endoscopic retrograde brush cytology was performed and was negative for malignancy in 3 cases. Steroid therapy was given in 3 and was responsive, but there were 2 recurrences.

CONCLUSION

AIP should be a differential diagnosis in distal CBD stricture and pancreatic head mass when the patient has: (1) diffuse or long segmental enlargement of the pancreas without peripancreatic fat infiltration, with multiple narrowing of the MPD without much upstream dilatation, or narrowing of the MPD not corresponding to the region of CBD stricture; and (2) abnormal immunoserologic tests.

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.

Review of idiopathic pancreatitis

Recent advances in understanding of pancreatitis and advances in technology have uncovered the veils of idiopathic pancreatitis to a point where a thorough history and judicious use of diagnostic techniques elucidate the cause in over 80% of cases. This review examines the multitude of etiologies of what were once labeled idiopathic pancreatitis and provides the current evidence on each. This review begins with a background review of the current epidemiology of idiopathic pancreatitis prior to discussion of various etiologies. Etiologies of medications, infections, toxins, autoimmune disorders, vascular causes, and anatomic and functional causes are explored in detail. We conclude with management of true idiopathic pancreatitis and a summary of the various etiologic agents. Throughout this review, areas of controversies are highlighted.

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.

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.

Autoimmune pancreatitis diagnosed after pancreatoduodenectomy and successfully treated with low-dose steroid

A 69-year-old woman presented with obstructive jaundice and a 30-mm hypoechoic mass in the pancreatic head on ultrasonography. Magnetic resonance imaging (MRI) revealed enlargement of the pancreatic head with dilatation of the upstream main pancreatic duct and no dilatation of the proximal biliary tree. Endoscopic retrograde pancreatography showed a localized irregular narrowing of the main pancreatic duct in the head of the pancreas. Pylorus-preserving pancreatoduodenectomy (PPPD) was performed under the diagnosis of pancreatic head cancer. Histopathological examination showed fibrosis with lymphoplasmacytic infiltration, suggesting the diagnosis of autoimmune pancreatitis (AIP). Serum IgG concentration was within normal limits immediately after the operation but was elevated 4 months later, when MRI showed enlargement of the remnant pancreas, with a peripheral rim of low intensity. Oral administration of prednisolone was initiated, at a dose of 5 mg/day. The serum IgG concentration declined and MRI showed improvement of the pancreatic enlargement and the disappearance of the peripheral rim. AIP has not relapsed for 1 year so far, with the patient being kept on 5 mg/day prednisolone. This communication reports a patient with AIP showing an interesting clinical course.

Pathology of autoimmune pancreatitis and tumor-forming pancreatitis

The most frequently recognized presentation of autoimmune pancreatitis (AIP) is that mimicking pancreatic cancer. It is also known that at some stage during the disease process chronic pancreatitis clinically presents as a tumorous swelling, often suspected of being a carcinoma. In Japan, this stage has also been proposed clinically to be tumor-forming pancreatitis. Hence, tumor-forming pancreatitis shows at least two distinct types: a reparative process for centriductal acute inflammation with a background of chronic pancreatitis, which is considered to have given rise to the tumor at some stage of chronic pancreatitis, and a lymphoplasmacytic infiltration with lymphoid and fibrous proliferation in normal pancreatic tissue, which corresponds to autoimmune pancreatitis. These tumorous lesions may be changeable along the disease process.

Diagnostic criteria for autoimmune chronic pancreatitis

Autoimmune chronic pancreatitis (AIP) is a clinically attractive entity because of its dramatic response to oral steroid therapy. Recently, as awareness of AIP is increasing, more cases are being reported. However, there are still no established worldwide diagnostic criteria for AIP. Since the Japan Pancreas Society (JPS) published diagnostic criteria for autoimmune chronic pancreatitis in the year 2002, increased attention toward this relatively new disease entity has enabled more cases of AIP to be correctly diagnosed. As previously unrecognized or misdiagnosed cases of autoimmune chronic pancreatitis are found, an increasing number of cases that are not in full accordance with the JPS diagnostic criteria are revealed. As a result, some groups have developed and cited their own criteria in the reporting of autoimmune chronic pancreatitis. The absence of consistent, uniform criteria has made comparison of different cases diagnosed under various guidelines difficult. In this review, we discuss and compare the four current sets of diagnostic criteria, focusing on their individual strengths and weaknesses.

Diagnosis of autoimmune pancreatitis using its five cardinal features: introducing the Mayo Clinic's HISORt criteria

Autoimmune pancreatitis (AIP) is a recently defined form of chronic pancreatitis. While numerous case reports and small case series of AIP have been reported from Japan, there have been relatively few from the West. Based on a retrospective review of our experience with resected AIP and a review of the literature, we have identified five cardinal features of AIP in histology, imaging, serology, other organ involvement, and response to steroid therapy, which are summarized in the mnemonic HISORt. A combination of the HISORt criteria can be used to definitively diagnose a wide spectrum of manifestations of AIP.

The diagnostic criteria for autoimmune chronic pancreatitis: it is time to make a consensus

Autoimmune chronic pancreatitis (AIP) is increasingly being recognized as a worldwide entity. In 2002, the Japan Pancreas Society published diagnostic criteria for AIP. Since then, increased attention toward this relatively new disease entity has enabled more cases of AIP to be correctly diagnosed, allowing for proper management and avoidance of surgery. Retrospective inclusion of previously unrecognized or misdiagnosed cases of AIP has revealed an increasing number of cases that are not in full accordance with the Japanese diagnostic criteria. As a result, some groups have developed and cited their own criteria in the reporting of AIP, and the Japan Pancreas Society criteria have also undergone revision recently. The absence of consistent and uniform criteria has made the comparison of different cases diagnosed under various guidelines difficult. In this review, we discuss and compare the 4 current diagnostic criteria, focusing on their own strength and weakness with the aim of providing a framework for the development of unified criteria that represent an international consensus.

Difficulty in diagnosing autoimmune pancreatitis by imaging findings

BACKGROUND

Autoimmune pancreatitis (AIP) presents as diffuse enlargement of the pancreas and as diffuse irregular narrowing of the main pancreatic duct. However, some AIP cases are difficult to diagnose because of atypical imaging findings.

OBJECTIVE

To clarify a variety of imaging findings of AIP and the reason for its misdiagnosis.

DESIGN

We examined the imaging findings of 37 AIP cases and also examined misdiagnosed cases of AIP to determine their reasons for misdiagnosis.

PATIENTS

A total of 37 patients with AIP who reported to our hospital or its affiliate over a 17-year period (1989 to May 2005).

RESULTS

Patients in 15 AIP cases showed segmental narrowing of the main pancreatic duct. There were 6 patients with focal enlargement of the pancreas, whereas 3 patients showed no enlargement. There were 3 cases of calcification of the pancreas. Pancreatic cysts were detected in 2 patients. Abdominal US showed multiple low-echoic masses in 1 case and a single mass in 3 cases. Sixteen patients had stenosis of the bile duct at the hilar hepatic lesion and/or the intrahepatic duct. Only 7 patients had typical AIP findings. Six patients were misdiagnosed with pancreatic cancer and 2 with bile-duct cancer. Seven cases were surgically treated. Five cases were misdiagnosed because of the nonexistence of, or the unfamiliarity with, the concept of AIP and sclerosing cholangitis with AIP. Another 3 cases were diagnosed with pancreatic cancer because of segmental stenosis of the main pancreatic duct and no or focal enlargement of the pancreas.

CONCLUSIONS

The results of this study suggest that AIP presents a variety of imaging findings. The most important diagnostic factor is clinician awareness of the concept of AIP and the diverse nature of imaging findings.

Pyogenic liver abscess after choledochoduodenostomy for biliary obstruction caused by autoimmune pancreatitis

A 68-year-old man underwent cholecystectomy and choledochoduodenostomy for biliary obstruction and nephrectomy for a renal tumor. Based on clinical and histopathologic findings, autoimmune pancreatitis (AIP) was diagnosed. The renal tumor was diagnosed as a renal cell cancer. Steroid therapy was started and thereafter pancreatic inflammation improved. Five years after surgery, the patient was readmitted because of pyrexia in a preshock state. A Klebsiella pneumoniae liver abscess complicated by sepsis was diagnosed. The patient recovered with percutaneous abscess drainage and administration of intravenous antibiotics. Liver abscess recurred 1 mo later but was successfully treated with antibiotics. There has been little information on long-term outcomes of patients with AIP treated with surgery. To our knowledge, this is the second case of liver abscess after surgical treatment of AIP.

[Autoimmune pancreatitis--a surgical disease?]

The term autoimmune pancreatitis (AIP) describes a nonalcoholic, chronic lymphoplasmocytic pancreatitis. The lymphoplasmocytic infiltration is characterized by periductal localization of predominantly CD4-positive T cells, fibrosis, and acinar atrophy, frequently resulting in stenosis of the main pancreatic and distal common bile ducts. Imaging studies often reveal a diffuse narrowing of the pancreatic main duct and swelling of the pancreatic head wrongly suggesting the presence of a malignant tumor. Clinical signs include mild abdominal pain, jaundice, recurrent episodes of acute pancreatitis, and even new-onset diabetes mellitus. Additionally, AIP can be associated with other autoimmune diseases such as Sjögren's syndrome, primary sclerosing cholangitis, chronic inflammatory bowel diseases, and retroperitoneal fibrosis. Serological markers include autoantibodies and increased levels of gamma globulin and especially IgG4. Steroids seem to be effective in improving clinical symptoms as well as in the resolution of pancreatic and bile duct narrowing. This distinguishes AIP from other forms of pancreatitis and from pancreatic neoplasms. Further studies of the underlying pathophysiologic mechanisms, prognosis, and new diagnostic tools are needed to provide adequate and effective treatment in the future. In this article, we summarize the current knowledge about AIP and present 17 cases that underwent surgical resection at our institution from 2003 to 2004.

Frequency and characteristics of pancreatitis in patients with inflammatory bowel disease

BACKGROUND AND AIMS

Clinical symptoms of inflammatory bowel disease (IBD)-associated pancreatitis are found in approximately 2% of patients, but the frequency of the disease could be much higher since IBD-associated pancreatitis could be mainly a silent disease. The aim of this study was to describe the radiological and biological features of IBD-associated pancreatitis and assess its frequency by comparing data from IBD patients with or without a history of pancreatitis.

METHODS

79 patients were prospectively enrolled (median age 36 years). Symptoms of pancreatitis had been previously recorded in 30 of them (group P; the other 49 patients (group C) had no history of pancreatitis. Pancreatic ductal changes were investigated by pancreato-MRI. Exocrine function was assessed by the fecal elastase test and by assaying serum amylase, lipase, C-reactive protein, PAP, IgG4 and pancreatic autoantibodies.

RESULTS

Increased levels of amylase and lipase occurred in 11% of IBD patients, that frequency being significantly higher in group P (23%) than in group C (4%) (p = 0.01). Low fecal elastase reflecting impaired exocrine function was observed in 30% of patients and again significantly more in group P (50%) than in group C (17%) (p = 0.04). The frequency of elevated values varied from 12% for amylase and lipase to 18% for PAP, 20% for pancreatic autoantibodies and 45% for CRP, without a difference between groups P and C. Silent exocrinopathy was observed in both groups, pancreatic autoantibodies and pancreatic duct alterations being found in 20 and 11% of patients, respectively.

CONCLUSION

Finding pancreatic insufficiency in about 30% of the included patients and in 50% of those with a previous history of pancreatitis suggests that IBD might be associated with chronic pancreatic alteration. Episodes of mild acute pancreatitis observed in some patients are not always due to adverse effects of treatments and can be acute manifestations of the chronic disease.

Diagnostic criteria for autoimmune chronic pancreatitis revisited

Autoimmune chronic pancreatitis (AIP) is increasingly being recognized worldwidely, as knowledge of this entity builds up. Above all, AIP is a very attractive disease to clinicians in terms of its dramatic response to the oral steroid therapy in contrast to ordinary chronic pancreatitis. Although many characteristic findings of AIP have been described, definite diagnostic criteria have not been fully established. In the year 2002, the Japan Pancreas Society published the diagnostic criteria of AIP and many clinicians around the world use these criteria for the diagnosis of AIP. The diagnostic criteria proposed by the Japan Pancreas Society, however, are not completely satisfactory and some groups use their own criteria in reporting AIP. This review discusses several potential limitations of current diagnostic criteria for this increasingly recognized condition. The manuscript is organized to emphasize the need for convening a consensus to develop improved diagnostic criteria.

Involvement of pancreatic and bile ducts in autoimmune pancreatitis

AIM: To examine the involvement of the pancreatic and bile ducts in patients with autoimmune pancreatitis.

METHODS: Clinical and cholangiopancreatographic findings of 28 patients with autoimmune pancreatitis were evaluated. For the purposes of this study, the pancreatic duct system was divided into three portions: the ventral pancreatic duct; the head portion of the dorsal pancreatic duct; and the body and tail of the dorsal pancreatic duct.

RESULTS: Both the ventral and dorsal pancreatic ducts were involved in 24 patients, while in 4 patients only the dorsal pancreatic duct was involved. Marked stricture of the bile duct was detected in 20 patients and their initial symptom was obstructive jaundice. Six patients showed moderate stenosis to 30%-40% of the normal diameter, and the other two patients showed no stenosis of the bile duct. Although marked stricture of the bile duct was detected in 83% (20/24) of patients who showed narrowing of both the ventral and dorsal pancreatic ducts, it was not observed in the 4 patients who showed involvement of the dorsal pancreatic duct alone (P = 0.0034).

CONCLUSION: Both the ventral and dorsal pancreatic and bile ducts are involved in patients with autoimmune pancreatitis.

Clinical and Pathologic Features of Proximal Biliary Strictures Masquerading as Hilar Cholangiocarcinoma

BACKGROUND

Nontraumatic inflammatory hilar strictures are uncommon, but are known to mimic malignancy. This study examines the clinical and pathologic features of benign idiopathic strictures.

STUDY DESIGN

Patients without a history of trauma or earlier biliary operation treated for benign strictures were identified. Clinical information was obtained from the medical record and all resected specimens were reexamined.

RESULTS

From January 1992 to July 2003, 275 patients with proximal biliary strictures were referred. Among these, 22 patients had a final histologic diagnosis of benign stricture, despite a suspected preoperative diagnosis of malignancy. All 22 patients underwent resection of the extrahepatic biliary tree, which in 10 patients was combined with en bloc partial hepatectomy. Histologic reexamination identified five different benign processes: lymphoplasmacytic sclerosing pancreatitis and cholangitis, primary sclerosing cholangitis, granulomatous disease, nonspecific fibrosis/inflammation, and stone disease. Major postoperative morbidity occurred in 6 (26%) patients but none died. No preoperative clinical or radiographic features were identified that could reliably distinguish patients with benign strictures from those with cancer.

CONCLUSIONS

"Malignant masquerade" of the proximal bile duct results from several different underlying conditions, and differentiating benign strictures from cancer remains problematic. The treatment approach should continue to be resection for presumed malignancy.

Duct-narrowing chronic pancreatitis without immunoserologic abnormality: comparison with duct-narrowing chronic pancreatitis with positive serological evidence and its clinical management

We reviewed the clinical features and clinical course of patients with duct-narrowing chronic pancreatitis who were negative for immunoserologic test results (n = 16) in comparison with the findings for serological test-positive patients (n = 20) in order to determine an adequate treatment for those who had typical morphology of autoimmune pancreatitis in the absence of immunoserologic abnormality. No significant differences were found between the two groups of patients in clinical profiles including associated autoimmune-related diseases, pancreatic histology, and response to steroid therapy. Of the seronegative patients, eight who showed an improvement in narrowing of the main pancreatic duct with steroid therapy and three who did no show an improvement or who relapsed after surgical resection without this therapy had stenosis of the common bile duct with increased levels of serum hepatobiliary enzymes, except for two patients with affected sites limited to the body or tail of the gland. For the remaining five patients, who showed an improvement in pancreatic duct changes or long-term remission after surgery without steroid administration, normal biochemistry test results for liver functions were obtained, with no abnormal cholangiographic findings in the three patients examined. Duct-narrowing chronic pancreatitis without immunoserologic abnormality overlaps in clinical features with that fulfilling the immunoserologic criteria for a diagnosis of autoimmune pancreatitis. In particular, the disease with bile duct involvement should be treated clinically as autoimmune pancreatitis, for which steroid therapy is recommended, even if an autoimmune mechanism is not demonstrated serologically.

Treating patients with autoimmune pancreatitis: results from a long-term follow-up study

BACKGROUND

Steroid therapy is currently common treatment for autoimmune pancreatitis (AIP); however, indications of steroid therapy have yet to be established, and the clinical course after steroid therapy is unknown.

METHODS

A total of 23 patients with AIP were subdivided into 4 groups according to the initial treatments undertaken. They were treated with pancreatoduodenectomy on suspicion of pancreatic tumor in 6 patients, choledochoduodenostomy with pancreatic biopsy in 4 patients, supportive therapy in 3 patients, and steroid therapy in 10 patients. Clinical course of AIP in each group was examined.

RESULTS

Prognosis of the AIP patients is almost good except for the 2 patients who progressed to pancreatic insufficiency after resection. Two patients without jaundice improved spontaneously. Steroid therapy was effective in all patients treated, but pancreatic atrophy developed in 5 of these patients. Steroid therapy improved insulin secretion and glycemic control in 4 of 7 diabetes mellitus (DM) patients.

CONCLUSION

To avoid futile surgery, in relatively elderly male patients with obstructive jaundice suggestive of pancreatic carcinoma, preoperative clinical suspicion of AIP is mandatory. Indications of steroid therapy for AIP are thought to be obstructive jaundice due to stenosis of the bile duct, other associated systemic autoimmune, and DM coincidental with AIP.

Autoimmune pancreatitis: increasing evidence for a clinical entity with various patterns

Autoimmune pancreatitis is a clinical entity with many different clinical and biological characteristics that make diagnosis difficult. Sensitive and specific pancreatic antibodies are still lacking to assess the diagnosis as is the availability of interpretable pathological specimens. However, suggestive features consist mainly of radiological findings and clinical anomalies, particularly if there are associated autoimmune-related diseases. The immunological pathway is probably of cell-mediated origin, although various autoantibodies, insensitive and non-specific, may exist. Finally, many studies are needed to define more efficient diagnostic criteria and to discover the true prevalence of autoimmune pancreatitis.

Autoimmune pancreatitis: imaging features

PURPOSE

To retrospectively determine imaging findings in patients with autoimmune pancreatitis.

MATERIALS AND METHODS

Twenty-nine patients (25 male and four female; mean age, 56 years; range, 15-82 years) with histopathologic diagnosis of autoimmune pancreatitis were examined. Data were reviewed by two radiologists in consensus. Imaging findings for review included those from helical computed tomography (CT), 25 patients; magnetic resonance (MR) imaging with MR cholangiopancreatography (MRCP), four patients; endoscopic ultrasonography (US), 21 patients; endoscopic retrograde cholangiopancreatography (ERCP), 19 patients; and percutaneous transhepatic cholangiography, one patient. Images were analyzed for appearances of pancreas, biliary and pancreatic ducts, and other findings, such as peripancreatic inflammation, encasement of vessels, mass effect, pancreatic calcification, peripancreatic nodes, and peripancreatic fluid collection. Follow-up images were available in nine patients. Serologic markers such as serum immunoglobulin G (IgG) and antinuclear antibody levels were available in 12 patients.

RESULTS

CT showed diffuse (n = 14) and focal (n = 7) enlargement of pancreas. Seven patients had minimal peripancreatic stranding, with lack of vascular encasement, calcification, or peripancreatic fluid collection. Nine patients had enlarged peripancreatic lymph nodes. MR imaging showed focal (n = 2) and diffuse (n = 2) enlargement with rimlike enhancement in one. MRCP revealed pancreatic duct strictures in two and sclerosing cholangitis-like appearance in one. Endoscopic US showed diffuse enlargement of pancreas with altered echotexture in 13 patients and focal mass in the head in six. ERCP showed stricture of distal common bile duct in 12 patients, irregular narrowing of intrahepatic ducts in six, diffuse irregular narrowing of pancreatic duct in nine, and focal stricture of proximal pancreatic duct in six. Serologic markers showed increased IgG and antinuclear antibody levels in seven of 12 patients. At follow-up, CT abnormalities and common bile duct strictures resolved after steroid therapy in three patients.

CONCLUSION

Features that suggest autoimmune pancreatitis include focal or diffuse pancreatic enlargement, with minimal peripancreatic inflammation and absence of vascular encasement or calcification at CT and endoscopic US, and diffuse irregular narrowing of main pancreatic duct, with associated multiple biliary strictures at ERCP.

Autoimmune chronic pancreatitis

In recent years a peculiar type of chronic pancreatitis with underlying autoimmunity has been described. Lymphoplasmacytic infiltration and fibrosis on histology and elevated IgG levels or detected autoantibodies on laboratory data support the concept of autoimmune chronic pancreatitis (AIP). Pancreatic imaging reveals a rare association of diffuse enlargement of the pancreas and irregular narrowing of the main pancreatic duct, which is unique and specific to AIP. Although AIP is not a common disease, it is increasingly being recognized as knowledge of this entity builds up. Clinically it is very important to be aware of this disease because AIP can clinically disguise as pancreaticobiliary malignancies, ordinary chronic, or acute pancreatitis. Above all, AIP is a very attractive disease to clinicians in terms of its dramatic response to oral steroid therapy in contrast to ordinary chronic pancreatitis. This review discusses the clinical, laboratory, histologic, and imaging findings that are seen in patients with AIP, especially focusing on the diagnosis.