Differentiation Of Autoimmune Pancreatitis Research Articles

Autoimmune pancreatitis versus pancreatic cancer

Autoimmune pancreatitis (AIP) is classified as a distinct form of pancreatitis according to the guidelines. It is characterized by imaging morphologic and histologic features and is associated with extrapancreatic manifestations in type1 IgG4-associated disease. Symptoms and findings almost always improve with administration of steroids. Differentiation from pancreatic ductal adenocarcinoma is required, particularly in the presence of AIP with focal parenchymal involvement. If AIP is suspected, abdominal ultrasound and/or endosonography, computed tomography (CT), and preferably magnetic resonance imaging (MRI) are indicated. A distinction is made between parenchymal and ductal changes that specifically indicate the presence of AIP. The diagnosis of autoimmune pancreatitis should be made based on the International Consensus Criteria (ICDC), in which the five main features (imaging, serology, histology, other organ involvement, response to steroid medication) are assessed. In type1 AIP, typical imaging changes are sufficient to establish the diagnosis even with negative histology, whereas for type2 AIP, histologic evidence is required. Imaging changes help in the differential diagnosis from pancreatic cancer. The following article addresses and evaluates crucial imaging diagnostic CT and MRI criteria for correct classification of findings, description of results, and differentiation of autoimmune pancreatitis from pancreatic cancer.

Differentiation of autoimmune pancreatitis from pancreatic adenocarcinoma using CT characteristics: a systematic review and meta-analysis.

To determine informational CT findings for distinguishing autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC) and to review their diagnostic accuracy. A systematic and detailed literature review was performed through PubMed, EMBASE, and the Cochrane library. Similar descriptors to embody the identical image finding were labeled as a single CT characteristic. We calculated the pooled diagnostic odds ratios (DORs) of each CT characteristic using a bivariate random-effects model. A total of 145 various descriptors from 15 studies (including 562 AIP and 869 PDAC patients) were categorized into 16 CT characteristics. According to the pooled DOR, 16 CT characteristics were classified into three groups (suggesting AIP, suggesting PDAC, and not informational). Seven characteristics suggesting AIP were diffuse pancreatic enlargement (DOR, 48), delayed homogeneous enhancement (DOR, 46), capsule-like rim (DOR, 34), multiple pancreatic masses (DOR, 16), renal involvement (DOR, 15), retroperitoneal fibrosis (DOR, 13), and bile duct involvement (DOR, 8). Delayed homogeneous enhancement showed a pooled sensitivity of 83% and specificity of 85%. The other six characteristics showed relatively low sensitivity (12-63%) but high specificity (93-99%). Four characteristics suggesting PDAC were discrete pancreatic mass (DOR, 23), pancreatic duct cutoff (DOR, 16), upstream main pancreatic duct dilatation (DOR, 8), and upstream parenchymal atrophy (DOR, 7). Eleven CT characteristics were informational to distinguish AIP from PDAC. Diffuse pancreatic enlargement, delayed homogeneous enhancement, and capsule-like rim suggested AIP with the highest DORs, whereas discrete pancreatic mass suggested PDAC. However, pooled sensitivities of informational CT characteristics were moderate. This meta-analysis underscores eleven distinctive CT characteristics that aid in differentiating autoimmune pancreatitis from pancreatic adenocarcinoma, potentially preventing misdiagnoses in patients presenting with focal/diffuse pancreatic enlargement. • Diffuse pancreatic enlargement (pooled diagnostic odds ratio [DOR], 48), delayed homogeneous enhancement (46), and capsule-like rim (34) were CT characteristics suggesting autoimmune pancreatitis. • The CT characteristics suggesting autoimmune pancreatitis, except delayed homogeneous enhancement, had a general tendency to show relatively low sensitivity (12-63%) but high specificity (93-99%). • Discrete pancreatic mass (pooled diagnostic odds ratio, 23) was the CT characteristic suggesting pancreatic ductal adenocarcinoma with the highest pooled DORs.

Deep Convolutional Neural Network-Assisted Feature Extraction for Diagnostic Discrimination and Feature Visualization in Pancreatic Ductal Adenocarcinoma (PDAC) versus Autoimmune Pancreatitis (AIP).

The differentiation of autoimmune pancreatitis (AIP) and pancreatic ductal adenocarcinoma (PDAC) poses a relevant diagnostic challenge and can lead to misdiagnosis and consequently poor patient outcome. Recent studies have shown that radiomics-based models can achieve high sensitivity and specificity in predicting both entities. However, radiomic features can only capture low level representations of the input image. In contrast, convolutional neural networks (CNNs) can learn and extract more complex representations which have been used for image classification to great success. In our retrospective observational study, we performed a deep learning-based feature extraction using CT-scans of both entities and compared the predictive value against traditional radiomic features. In total, 86 patients, 44 with AIP and 42 with PDACs, were analyzed. Whole pancreas segmentation was automatically performed on CT-scans during the portal venous phase. The segmentation masks were manually checked and corrected if necessary. In total, 1411 radiomic features were extracted using PyRadiomics and 256 features (deep features) were extracted using an intermediate layer of a convolutional neural network (CNN). After feature selection and normalization, an extremely randomized trees algorithm was trained and tested using a two-fold shuffle-split cross-validation with a test sample of 20% (n = 18) to discriminate between AIP or PDAC. Feature maps were plotted and visual difference was noted. The machine learning (ML) model achieved a sensitivity, specificity, and ROC-AUC of 0.89 ± 0.11, 0.83 ± 0.06, and 0.90 ± 0.02 for the deep features and 0.72 ± 0.11, 0.78 ± 0.06, and 0.80 ± 0.01 for the radiomic features. Visualization of feature maps indicated different activation patterns for AIP and PDAC. We successfully trained a machine learning model using deep feature extraction from CT-images to differentiate between AIP and PDAC. In comparison to traditional radiomic features, deep features achieved a higher sensitivity, specificity, and ROC-AUC. Visualization of deep features could further improve the diagnostic accuracy of non-invasive differentiation of AIP and PDAC.

Differentiation of autoimmune pancreatitis and pancreatic ductal adenocarcinoma based on multi-modality texture features in 18F-FDG PET/CT

Autoimmune pancreatitis (AIP) is a unique subtype of chronic pancreatitis, which shares many clinical presentations with pancreatic ductal adenocarcinoma (PDA). The misdiagnosis of AIP often leads to unnecessary pancreatic resection. 18F-FDG positron emission tomography/ computed tomography (PET/CT) could provide comprehensive information on the morphology, density, and functional metabolism of the pancreas at the same time. It has been proved to be a promising modality for noninvasive differentiation between AIP and PDA. However, there is a lack of clinical analysis of PET/CT image texture features. Difficulty still remains in differentiating AIP and PDA based on commonly used diagnostic methods. Therefore, this paper studied the differentiation of AIP and PDA based on multi-modality texture features. We utilized multiple feature extraction algorithms to extract the texture features from CT and PET images at first. Then, the Fisher criterion and sequence forward floating selection algorithm (SFFS) combined with support vector machine (SVM) was employed to select the optimal multi-modality feature subset. Finally, the SVM classifier was used to differentiate AIP from PDA. The results prove that texture analysis of lesions helps to achieve accurate differentiation of AIP and PDA.

Differentiation of Autoimmune Pancreatitis from Pancreatic Cancer Remains Challenging.

Autoimmune pancreatitis (AIP) is an uncommon form of chronic pancreatitis. Whilst being corticosteroid responsive, AIP often masquerades radiologically as pancreatic neoplasia. Our aim is to appraise demographic, radiological and histological features in our cohort in order to differentiate AIP from pancreatic malignancy. Clinical, biochemical, histological and radiological details of all AIP patients 1997-2016 were analysed. The initial imaging was re-reviewed according to international guidelines by three blinded independent radiologists to evaluate features associated with autoimmune pancreatitis and pancreatic cancer. There were a total of 45 patients: 25 in type 1 (55.5%), 14 type 2 (31.1%) and 6 AIP otherwise not specified (13.3%). The median (IQR) age was 57 (51-70) years. Thirty patients (66.6%) were male. Twenty-six patients (57.8%) had resection for suspected malignancy and one for symptomatic chronic pancreatitis. Three had histologically proven malignancy with concurrent AIP. Two patients died from recurrent pancreatic cancer following resection. Multidisciplinary team review based on radiology and clinical history dictated management. Resected patients (vs. non-resected group) were older (64 vs. 53, p = 0.003) and more frequently had co-existing autoimmune pathologies (22.2 vs. 55.6%, p = 0.022). Resected patients also presented with less classical radiological features of AIP, which are halo sign (0/25 vs. 3/17, p = 0.029) and loss of pancreatic clefts (18/25 vs. 17/17, p = 0.017). There were no differences in demographic features other than age. Despite international guidelines for diagnosing AIP, differentiation from pancreatic cancer remains challenging. Resection remains an important treatment option in suspected cancer or where conservative treatment fails.

Differentiation of autoimmune pancreatitis from pancreatic cancer remains challenging

Differentiation of autoimmune pancreatitis from pancreatic cancer remains challenging

Serum IgG subtypes features and differential diagnosis of autoimmunepancreatitis patients

To investigate clinical value of serum IgG subclass distribution in differential diagnosis of autoimmune pancreatitis. Inpatients were enrolled as follow, autoimmune pancreatitis (AIP, n=28), acute and chronic pancreatitis (ACP, n=112), pancreatic cancer (PC, n=15), cholangiocarcinoma (CC, n=9), retroperitoneal fibrosis (RPF, n=37), together with healthy controls (n=52). IgG subtypes, amylase, lipase, glucose and CA19-9 were tested.For patients with autoimmune pancreatitis and pancreatic cancer, radiographic CT of abdomen and pathological staining were included for comparison. IgG4 subtype distributed in a wide range as 7.6(1.7-13.8) g/L in AIP, 0.4(0.2-0.7) g/L in ACP, 0.7(0.2-0.9) g/L in PC, 0.5(0.4-6.5) g/L in CC and 0.4(0.2-0.7) g/L in control group, the difference was significant (H=40.536, P<0.001). There were no significant differences of IgG1, IgG3 level in AIP, RPC and control group (all P>0.05). While IgG4 level was 7.6(1.7-13.8), 1.3(0.5-2.6), 0.4(0.2-0.7) g/L in AIP, RPC and control group, respectively. The difference was significant (H=36.833, P<0.001). IgG4 level in RPC group was lower than that in AIP group (P<0.05). And it was meaningful in the differential diagnosis. Serum IgG4 subtype plays an important role in differentiation of autoimmune pancreatitis from associated diseases.

The differentiation of autoimmune pancreatitis and pancreatic cancer using imaging findings.

Differentiation of autoimmune pancreatitis (AIP) and pancreatic cancer (PC) is important to avoid unnecessary surgery. The aim of this study was to compare various image findings and facilitate the differentiation of these two diseases. The radiological features of 36 AIP patients and 36 patients with resected PC diagnosed at Samsung Medical Center from January 1991 to October 2010, were compared. Regarding CT/MRI findings, diffuse pancreas enlargement, capsule-like rim and delayed homogenous enhancement, were significantly more frequent in AIP. For cholangiopancreatography findings, main pancreatic duct (MPD) narrowing by ≥1/3 of the pancreatic length, skipped lesions of the MPD, the presence of side branches at the narrowed MPD portion, and smooth and straight intrapancreatic common bile duct stenosis were significantly more frequent in AIP. However, according to FDG-PET findings, SUVmax, uptake shape and pattern, and uptake by extrapancreatic lesions were not significantly different for AIP and PC. Diffuse pancreas enlargement, a capsule-like rim, delayed homogenous enhancement, MPD narrowing of ≥1/3 of the pancreatic length, skipped lesions and the presence of side branches at the narrow MPD portion were found to have high specificity for AIP. These findings have great power to differentiate AIP and PC.

Differentiation of autoimmune pancreatitis with pancreatic carcinoma remains a challenge to physicians

The aim of this study was to summarize the clinical features of autoimmune pancreatitis (AIP) and review the advances in the differential diagnosis with pancreatic carcinoma, thus help to make a correct diagnosis and avoid unnecessary surgery in clinical practice. Five patients diagnosed as AIP in accordance with the HISORt criteria in Zhongshan Hospital, Fudan University from 2008 to 2010 were enrolled in the study. Clinical features were analyzed and related literature was reviewed. Progressive jaundice and abdominal pain were the most frequent symptoms, as well as weight loss, together with serological changes such as elevation of alkaline phosphatase, γ-glutamyl-transpeptidase and serum bilirubin. Two of them showed high serum immunoglobulin G4 (IgG4) levels. Both focal and diffuse changes were found on computed tomography and magnetic resonance imaging. Two of our patients underwent operation because of a high suspicion of malignant tumor, and steroid therapy was administered to the other three patients diagnosed as AIP. No relapse was observed during the follow-up duration of all the patients. Although some recent advances have been made to help the diagnosis of AIP, the differentiation between AIP and pancreatic carcinoma is still a challenge. Clinicians must remember to exclude AIP before making a diagnosis of pancreatic carcinoma.

The quandary of autoimmune pancreatitis and pancreatic ductal adenocarcinoma: A case report and review of IgG4 immunostaining in a cohort of patients receiving neoadjuvant chemotherapy

ABSTRACT Introduction: Autoimmune pancreatitis (AIP) is an inflammatory disease whose clinical presentation can mimic that of pancreatic ductal adenocarcinoma (PDA). AIP can appear on imaging as a bulky, sausage­like pancreatic mass with biliary and pancreatic ductal obstruction, resembling the classic “double duct sign” appearance of PDA. A definitive preoperative diagnosis of AIP can be difficult because the two diseases (AIP and PDA) are similar in clinical presentation. Recent advances in serum marker evaluation such as IgG4 serum levels and immunostaining techniques have shown some promise in the differentiation of AIP from PDA. Case Report: We report the case of a patient with a preoperative diagnosis of locally advanced PDA who was treated with neoadjuvant gemcitabine based chemotherapy followed by surgical resection, but whose post­ resection pathology was indicative of AIP and not PDA. To explore the possibility that the pre­ resection gemcitabine­based chemotherapy had generated a complete pathological response and an inflammatory reaction of IgG4­positive plasma cells, we studied the histology features and IgG4 plasma cell immunostaining characteristics of the pathology specimens of 14 patients with a diagnosis of PDAwho were treated with neoadjuvant chemotherapy and surgical resection at our institution. Conclusion: Our results indicate that none of the patients treated with neoadjuvant chemotherapy had increased IgG4­positive plasma cell immunostaining post­ operatively, further supporting the diagnosis of AIP and not PDA in our patient.

Endoscopic ultrasound-guided fine needle aspiration in the differentiation of type 1 and type 2 autoimmune pancreatitis

To investigate the usefulness of endoscopic ultra-sound-guided fine needle aspiration (EUS-FNA) in the differentiation of autoimmune pancreatitis (AIP). We retrospectively reviewed 47 of 56 AIP patients who underwent EUS-FNA and met the Asian diagnostic criteria. On 47 EUS-FNA specimens, we evaluated the presence of adequate material and characteristic features of lymphoplasmacytic sclerosing pancreatitis (LPSP) and idiopathic duct-centric pancreatitis (IDCP) mentioned in the International Consensus Diagnostic Criteria and examined if these findings make a contribution to the differential diagnosis of type 1 and type 2 AIP. A disposable 22-gauge needle was used for EUS-FNA. Adequate specimens including pancreatic tissue for differentiating AIP from cancer were obtained from 43 of 47 patients who underwent EUS-FNA. EUS-FNA was performed from the pancreatic head in 21 cases, which is known to be technically difficult when performed by core biopsy; there was no significant difference in the results compared with pancreatic body-tail. Nine of 47 patients met level 1 findings of LPSP and 5 patients met level 2 findings of LPSP. No one met level 1 findings of IDCP, but 3 patients met level 2 findings of IDCP. Of 10 seronegative cases, 2 cases were diagnosed with "definitive type 1 AIP", and 3 cases were diagnosed with "probable type 2 AIP" when considering both the level 2 histological findings and response to steroids. EUS-FNA is useful in the differentiation of type 1 and type 2 AIP, particularly in seronegative cases.

Differentiation of autoimmune pancreatitis from pancreas cancer: utility of anti-amylase and anti-carbonic anhydrase II autoantibodies.

PurposeTo investigate the utility of different combinations of serum anti-carbonic anhydrase II antibodies (CA II Abs), anti-α amylase antibodies (AMY-α Abs) and IgG4 levels for the diagnosis of autoimmune pancreatitis (AIP).MethodsWe recruited 93 patients with clinical suspicion for AIP and 94 patients as control groups between June 2003 and October 2009. Serum antibodies were measured using homemade enzyme linked immunosorbent assay and IgG4 levels were determined by nephelometry.ResultsBoth CA-II Abs and AMY-α Abs had the highest sensitivity (83%) although AMY-α Abs (89%) were more specific than CA-II Abs (75%). The presence of increased IgG4 levels was the most specific serological marker (94%), but it had the lowest sensitivity (58%). The combination of the three serological markers altogether had the highest specificity (99%) and positive predictive value (PPV) (86%), but they had a rather low sensitivity (50%). When we combined CA-II Abs and AMY-α Abs without IgG4 levels, we got the highest sensitivity (75%) and negative predictive value (98%) but the specificity and the PPV decreased to 93 and 50%, respectively. Importantly, AMY-α Abs were not detected in pancreas cancer.ConclusionsThe presence of serum CA-II and AMY-α Abs with increased IgG4 is useful in the differential diagnosis of AIP from pancreatic cancer.

Autoimmune pancreatitis and IgG4-related sclerosing cholangitis

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

The Combined Measurement of Total Serum IgG and IgG4 May Increase Diagnostic Sensitivity for Autoimmune Pancreatitis Without Sacrificing Specificity, Compared With IgG4 Alone

Until now, there was no international consensus on the diagnostic criteria for autoimmune pancreatitis (AIP). As for serologic criteria, the HISORt criteria use elevated immunoglobulin (Ig) G4 alone, whereas the Asian diagnostic criteria include elevations of total IgG or IgG4, or the presence of autoantibodies. This study was mainly aimed at determining whether the combined measurement of total IgG and IgG4 could increase the diagnostic sensitivity for AIP while maintaining specificity, compared with IgG4 alone. Another aim was to determine the utility of autoantibodies to diagnose AIP. We prospectively measured total serum IgG and IgG4 together in 82 consecutive patients with AIP, and seropositivity was defined as elevation of either total IgG or IgG4. To evaluate specificity in the differentiation of AIP from pancreatic cancer, total serum IgG and IgG4 were prospectively measured in 110 patients with pancreatic cancer. Also, the detection rates of antinuclear antibody (ANA) and rheumatoid factor (RF) were retrospectively reviewed in patients with AIP. In patients with AIP, the sensitivity of IgG4 (> or = 135 mg/dl) was 52.5% (43/82), significantly higher than that (46.3%, 38/82) of total IgG (> or = 1,800 mg/dl) (P<0.05). The sensitivity of combined measurement of total IgG and IgG4 for AIP was 68.3% (56/82), significantly higher than that of IgG4 alone (P<0.05). The specificity of total IgG and IgG4 in the differentiation of AIP from pancreatic cancer was 96.4 and 99.1%, respectively. The specificity of combined measurement of total IgG and IgG4 was 95.5%, and it was not significantly different from that of IgG4 alone (P=0.125). The sensitivity of ANA (> or = 1:80) and RF was 24.4% (19/78) and 20.3% (13/64), respectively. All but one patient who had positive results for ANA or RF also showed elevations of either total IgG or IgG4, respectively. The combined measurement of total serum IgG and IgG4 may increase diagnostic sensitivity without sacrificing specificity, compared with IgG4 alone. However, the measurement of ANA or RF may show no additional benefit when combined with total serum IgG and IgG4.

Decreased production of immunoglobulin M and A in autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a rare type of chronic pancreatitis caused by an autoimmune abnormality. It is well known that high serum concentrations of IgG4 are helpful for making a diagnosis of AIP; however, it is unclear whether there are abnormalities in the production of other immunoglobulins in AIP. We examined the immune condition of AIP patients before and after glucocorticoid treatment, focusing on serum levels of IgG, IgG4, IgM and IgA, and compared the results with those in other hepato-pancreatic diseases, such as autoimmune hepatitis, primary biliary cirrhosis, chronic pancreatitis and pancreatic carcinoma. IgM and IgA were decreased in patients with untreated AIP. IgM and IgG or IgG4 were negatively correlated in patients with AIP. The ratios of IgG to IgM and IgG to IgA in patients with AIP were significantly increased compared with the other diseases. The diagnostic sensitivity of IgG to IgM and IgG to IgA was 0.800 and 0.950, and the specificity of each ratio was 0.703 and 0.728, respectively, in the differentiation of AIP from the other diseases. IgM was not significantly changed after glucocorticoid treatment in the patients with AIP, while IgG, IgG4 and IgA decreased. The ratios of IgG to IgM and IgG to IgA may serve as novel diagnostic markers to differentiate AIP from other hepato-pancreatic diseases. Furthermore, low concentrations of IgM and IgA may be involved in the pathogenesis of AIP.

Differentiation of autoimmune pancreatitis from suspected pancreatic cancer by fluorine-18 fluorodeoxyglucose positron emission tomography

Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) has been widely used for the diagnosis of pancreatic cancer. Because autoimmune pancreatitis is easily misdiagnosed as pancreatic cancer and can be tested for by FDG-PET analysis based on the presence of suspected pancreatic cancer, we attempted to clarify the differences in FDG-PET findings between the two conditions. We compared FDG-PET findings between 15 patients with autoimmune pancreatitis and 26 patients with pancreatic cancer. The findings were evaluated visually or semiquantitatively using the maximum standardized uptake value and the accumulation pattern of FDG. FDG uptake was found in all 15 patients with autoimmune pancreatitis, whereas it was found in 19 of 26 patients (73.1%) with pancreatic cancer. An accumulation pattern characterized by nodular shapes was significantly more frequent in pancreatic cancer, whereas a longitudinal shape indicated autoimmune pancreatitis. Heterogeneous accumulation was found in almost all cases of autoimmune pancreatitis, whereas homogeneous accumulation was found in pancreatic cancer. Significantly more cases of pancreatic cancer showed solitary localization, whereas multiple localization in the pancreas favored the presence of autoimmune pancreatitis. FDG uptake by the hilar lymph node was significantly more frequent in autoimmune pancreatitis than in pancreatic cancer, and uptake by the lachrymal gland, salivary gland, biliary duct, retroperitoneal space, and prostate were seen only in autoimmune pancreatitis. FDG-PET is a useful tool for differentiating autoimmune pancreatitis from suspected pancreatic cancer, if the accumulation pattern and extrapancreatic involvement are considered. IgG4 measurement and other current image tests can further confirm the diagnosis.

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

Aim To describe the occurrence of renal cortical lesions (RCLs) in patients with autoimmune pancreatitis (AIP). Methods This retrospective study was approved by our research ethics board; informed consent was waived. Systematic search of CT scan reports in 5-year interval yielded 17 patients with AIP (male:female; 11:6, age 18–80 years). A consecutive group of 22 patients with pancreatic adenocarcinoma was used as control (male:female; 10:12, age 42–76 years). The CT scans of the two groups were mixed and randomized. Two blinded radiologists independently reviewed the kidneys for the presence of wedge-shaped RCLs. Fisher's exact test was used to determine statistical significance. Consensus review of all imaging of positive patients with AIP and RCLs and three additional patients identified anecdotally was performed. Results Both readers independently identified the same 6/17 (35%) patients in the study group and 0/22 in the control group with two or more RCLs. This difference was statistically significant ( p = 0.004). The sensitivity, specificity, positive and negative predictive values of RCLs in the differentiation of AIP from pancreatic adenocarcinoma were 35%, 100%, 100%, and 67%, respectively. To the six AIP patients with RCLs, we added three more identified anecdotally. In 7/9, >5 RCLs were seen which were wedge-shaped and cortical-based, ranging from <1 to 4 cm. Typical pancreatic findings of AIP were noted in all, with the gland affected focally in 5/9 patients. Conclusion We have shown the presence of multiple renal cortical lesions which occur in ∼35% of our AIP patient population.

Angiographic Findings in Patients with Autoimmune Pancreatitis

Editor: I read with great interest the article by Dr Sahani and colleagues in the November 2004 issue of Radiology (1). They analyzed in detail imaging findings in patients with autoimmune pancreatitis. They reported that homogeneous enhancement of the enlarged pancreas with absence of vascular enlargement at computed tomography (CT) was helpful in the differentiation of autoimmune pancreatitis and pancreatic carcinoma. In our angiographic study, however, abnormalities were detected in seven of 13 patients with autoimmune pancreatitis (54%), with irregular narrowing of the anterior superior pancreaticoduodenal artery, posterior superior pancreaticoduodenal artery, and transpancreatic artery, which was evident in seven (54%), four (31%), and two (15%) of 13 patients, respectively. Deviation of the portal or splenic vein was observed in 31% of cases, and these veins were poorly opacified, with collateral veins evident because of stenosis or obstruction in 23% (2). One of the characteristic histologic findings of autoimmune pancreatitis is obliterative phlebitis with lymphoplasmacytic infiltration and proliferation of fibroblasts in and around the walls of the veins, sometimes involving the portal vein (3). In addition, duplication of the internal elastica and intimal thickening are occasionally observed in the small arteries (4). The presence of irregular narrowing of the pancreatic arteries, similar to encasement sometimes detected in pancreatic carcinoma, and stenosis or obstruction of the portal vein could result from the histologic changes described before. Moreover, deviation of the portal veins could be secondary to pancreatic enlargement. These angiographic findings can cause confusion in the diagnosis of autoimmune pancreatitis.

Clinical difficulties in the differentiation of autoimmune pancreatitis and pancreatic carcinoma

Objectives Autoimmune pancreatitis (AIP) is a newly described entity with characteristic clinical, histologic, and morphologic changes, in which autoimmune mechanisms are involved in pathogenesis. However, difficulties can arise in the differentiation of AIP from pancreatic carcinoma. The aims of this study were to clarify clinical and radiologic features of AIP to elucidate areas of diagnostic confusion. Methods Clinical, serologic, and radiologic findings were evaluated in 17 patients with AIP . Results All 17 patients were initially suspected to have pancreatic carcinoma. The patients were predominantly elderly men who frequently presented with jaundice but without features of acute pancreatitis. Elevation of serum γ-globulin and IgG along with the presence of autoantibodies were usually evident, whereas serum tumor markers were elevated in 54% of cases. Stenosis of the bile duct was detected in 94% of cases. Diffuse enlargement of the pancreas and irregular narrowing of the main pancreatic duct were radiologically characteristic; however, segmental swelling and narrowing were detected in seven and two patients, respectively. In segmental cases, neither atrophy of the distal pancreas nor marked upstream dilation of the distal main pancreatic duct was observed. Angiographic abnormalities occurred in 54% of cases. Serologic and radiologic abnormalities showed considerable improvement with steroid therapy. Conclusions Frequent stenosis of the bile duct, elevation of serum tumor markers, segmental pancreatic enlargement or narrowing of the main pancreatic duct, and angiographic abnormalities can cause confusion in the differential diagnosis of AIP and pancreatic carcinoma.

Clinical difficulties in the differentiation of autoimmune pancreatitis and pancreatic carcinoma.

Autoimmune pancreatitis (AIP) is a newly described entity with characteristic clinical, histologic, and morphologic changes, in which autoimmune mechanisms are involved in pathogenesis. However, difficulties can arise in the differentiation of AIP from pancreatic carcinoma. The aims of this study were to clarify clinical and radiologic features of AIP to elucidate areas of diagnostic confusion. Clinical, serologic, and radiologic findings were evaluated in 17 patients with AIP. All 17 patients were initially suspected to have pancreatic carcinoma. The patients were predominantly elderly men who frequently presented with jaundice but without features of acute pancreatitis. Elevation of serum gamma-globulin and IgG along with the presence of autoantibodies were usually evident, whereas serum tumor markers were elevated in 54% of cases. Stenosis of the bile duct was detected in 94% of cases. Diffuse enlargement of the pancreas and irregular narrowing of the main pancreatic duct were radiologically characteristic; however, segmental swelling and narrowing were detected in seven and two patients, respectively. In segmental cases, neither atrophy of the distal pancreas nor marked upstream dilation of the distal main pancreatic duct was observed. Angiographic abnormalities occurred in 54% of cases. Serologic and radiologic abnormalities showed considerable improvement with steroid therapy. Frequent stenosis of the bile duct, elevation of serum tumor markers, segmental pancreatic enlargement or narrowing of the main pancreatic duct, and angiographic abnormalities can cause confusion in the differential diagnosis of AIP and pancreatic carcinoma.