Extrapancreatic lesions in autoimmune pancreatitis

Peripancreatic vascular involvement in patients with type 1 autoimmune pancreatitis

BACKGROUND

Type 1 autoimmune pancreatitis (AIP) is the pancreatic manifestation of IgG4-related disease. However, this benign disease can result in the peripancreatic vascular involvement (PVI) on occasion, which increases the difficulty of diagnosis and treatment of this clinical entity as well as for differentiating it from pancreatic malignancies.

METHODS

We retrospectively reviewed the information on demographics, clinical presentation, laboratory, imaging and endoscopic findings of 101 hospitalized patients with type 1 AIP treated in our department. All the patients were divided into non-PVI and PVI groups according to the first hospitalized medical data. Univariate and multivariate analyses were performed to analyse the potential predictive parameter(s) of PVI in AIP patients.

RESULTS

Among the 101 type 1 AIP patients, 52 (51.5%) exhibited PVI, with a male/female ratio 5.5:1. Their average age was 58.37±8.68 years old. Univariate analysis revealed that the location of pancreatitis lesions, including the pancreatic tail (P=0.010), the presence of splenomegaly (P=0.001) and the white blood cell (WBC) number in peripheral blood (P=0.020), were significantly associated with PVI. The location of pancreatitis lesions, including the pancreatic tail (P=0.023), and the presence of splenomegaly (P=0.010) were found to be independent predictors of the development of PVI by a multivariable regression analysis. A total of 18 out of 25 patients in PVI group who underwent corticosteroid treatment and no less than 6 months radiological follow-up showed improvement in vascular lesions, and no case exhibited exacerbation of PVI lesions during follow-up. Of 36 patients in non-PVI group who were followed up for no less than 6 months, only one case exhibited PVI.

CONCLUSIONS

This retrospective study demonstrated that type 1 AIP was associated with a high proportion of PVI. Pancreatic tail involvement and splenomegaly may predict the PVI in type 1 AIP. PVI lesions are reversible in a subset of patients.

Utilisation of artificial intelligence for the development of an EUS-convolutional neural network model trained to enhance the diagnosis of autoimmune pancreatitis

OBJECTIVE

The diagnosis of autoimmune pancreatitis (AIP) is challenging. Sonographic and cross-sectional imaging findings of AIP closely mimic pancreatic ductal adenocarcinoma (PDAC) and techniques for tissue sampling of AIP are suboptimal. These limitations often result in delayed or failed diagnosis, which negatively impact patient management and outcomes. This study aimed to create an endoscopic ultrasound (EUS)-based convolutional neural network (CNN) model trained to differentiate AIP from PDAC, chronic pancreatitis (CP) and normal pancreas (NP), with sufficient performance to analyse EUS video in real time.

DESIGN

A database of still image and video data obtained from EUS examinations of cases of AIP, PDAC, CP and NP was used to develop a CNN. Occlusion heatmap analysis was used to identify sonographic features the CNN valued when differentiating AIP from PDAC.

RESULTS

From 583 patients (146 AIP, 292 PDAC, 72 CP and 73 NP), a total of 1 174 461 unique EUS images were extracted. For video data, the CNN processed 955 EUS frames per second and was: 99% sensitive, 98% specific for distinguishing AIP from NP; 94% sensitive, 71% specific for distinguishing AIP from CP; 90% sensitive, 93% specific for distinguishing AIP from PDAC; and 90% sensitive, 85% specific for distinguishing AIP from all studied conditions (ie, PDAC, CP and NP).

CONCLUSION

The developed EUS-CNN model accurately differentiated AIP from PDAC and benign pancreatic conditions, thereby offering the capability of earlier and more accurate diagnosis. Use of this model offers the potential for more timely and appropriate patient care and improved outcome.

IgG4-Related Disease with Emphasis on Its Gastrointestinal Manifestation

IgG4-related disease is an immune-mediated fibroinflammatory condition with a diverse spectrum of organ involvement, commonly in the pancreas and bile ducts among other organs such as salivary and lacrimal glands. Classic histopathologic findings are the gold standard for confirmation of diagnosis, although diagnosis remains challenging, as biomarkers to date are neither sufficient nor necessary. Glucocorticoids are the most effective initial treatment, generally having a dramatic response, although limited clinical evidence exists regarding effective maintenance therapy. This review summarizes key GI manifestations of this condition for the practicing gastroenterologist and addresses the pathology, disease mechanism, and current therapeutic recommendations.

Abdominal manifestations of IgG4-related disease: a pictorial review

In the last decade, autoimmune pancreatitis has become recognised as part of a wider spectrum of IgG4-related disease, typically associated with elevated serum IgG4 levels and demonstrating a response to corticosteroid therapy. Radiologically, there is imaging overlap with other benign and neoplastic conditions. This pictorial review discusses the intra-abdominal manifestations of this disease on cross-sectional imaging before and after steroid treatment and the main radiological features which help to distinguish it from other key differentials.

TEACHING POINTS

• Autoimmune pancreatitis is part of a spectrum of IgG4-related disease. • Diagnosis is based on raised serum IgG4, clinical, radiological and histopathological findings. • Cross-sectional imaging can demonstrate the typical findings of abdominal IgG4-related disease. • Cross-sectional imaging can be used to monitor response to corticosteroid treatment.

Cholangiocarcinoma and its mimickers in primary sclerosing cholangitis

Cholangiocarcinoma (CCA) is the most common malignancy in primary sclerosing cholangitis (PSC). Approximately half of CCA are diagnosed within two years of initial diagnosis and often have a poor prognosis because of advanced tumor stage at the time of diagnosis. Thus, rigorous initial imaging evaluation for detecting CCA is important. CCA in PSC usually manifests as intrahepatic mass-forming or perihilar periductal-infiltrating type. Imaging diagnosis is often challenging due to pre-existing biliary strictures and heterogeneous liver. Multimodality imaging approach and careful comparison with prior images are often helpful in detecting small CCA. Ultrasound is widely used as an initial test, but has a limited ability to detect small tumors in the heterogeneous liver with PSC. MRI combined with MRCP is excellent to demonstrate focal biliary abnormalities as well as subtle liver masses. Contrast-enhanced ultrasound is useful to demonstrate CCA by demonstrating rapid and marked washout. In addition, there are other disease entities that mimic CCA including hepatocellular carcinoma, confluent hepatic fibrosis, IgG4-related sclerosing cholangitis, inflammatory mass, and focal fat deposition. In this pictorial essay, imaging findings of CCA in PSC is described and discuss the challenges in imaging surveillance for CCA in the patients with PSC. Imaging findings of the mimickers of CCA in PSC and their differentiating features are also discussed.

Comparison of the multidetector-row computed tomography findings of IgG4-related sclerosing cholangitis and extrahepatic cholangiocarcinoma

AIM

To compare the multidetector-row computed tomography (MDCT) findings of IgG4-related sclerosing cholangitis (IgG4-SC) and extrahepatic cholangiocarcinoma (EH-CCA).

MATERIALS AND METHODS

Two radiologists who had no knowledge of the patients' clinical information retrospectively evaluated the CT findings of patients with IgG4-SC (n=33) and EH-CCA (n=39) on a consensus basis. Another radiologist measured the biliary lesions. IgG4-SC was diagnosed using the Japan Biliary Association criteria (2012) or the Mayo Clinic's HISORt criteria. EH-CCA was diagnosed based on surgical findings.

RESULTS

Compared with EH-CCA, IgG4-SC exhibited the following findings significantly more frequently: (a) wall thickening alone, (b) concentric wall thickening, (c) smooth inner margins, (d) homogeneous attenuation in the arterial phase, (e) a lesion involving the intrapancreatic bile duct, (f) smooth outer margins, (g) fully visible lumen, (h) a funnel-shaped proximal bile duct, (i) skip lesions, and (j) abnormal pancreatic findings. Conversely, (k) dual-layered attenuation in all phases was significantly more common in EH-CCA. The specificity values of parameters (e-k) were >80%. Regarding dimensions, (l) the biliary lesions were longer in IgG4-SC than in EH-CCA. (m) The diameters of the dilated proximal common bile duct and (n) the dilated proximal intrahepatic bile duct were smaller in IgG4-SC than in EH-CCA.

CONCLUSION

A number of CT findings are useful for differentiating between IgG4-SC and EH-CCA. CT findings (e-k) are particularly useful for this purpose.

Cerebral involvement in IgG4-related disease

IgG4-related disease is a recently recognised multi-system disease. Common organ involvement includes the pancreas, biliary tree and salivary glands. Central nervous system involvement has been infrequently reported. In a single-centre cohort of 84 patients, we report cerebral involvement in three (4%) patients. Details of cerebral involvement in these patients are outlined, including pituitary involvement in two patients and a diffuse autoimmune-like encephalopathy in the other.

Adult bile duct strictures: role of MR imaging and MR cholangiopancreatography in characterization

Bile duct strictures in adults are secondary to a wide spectrum of benign and malignant pathologic conditions. Benign causes of bile duct strictures include iatrogenic causes, acute or chronic pancreatitis, choledocholithiasis, primary sclerosing cholangitis, IgG4-related sclerosing cholangitis, liver transplantation, recurrent pyogenic cholangitis, Mirizzi syndrome, acquired immunodeficiency syndrome cholangiopathy, and sphincter of Oddi dysfunction. Malignant causes include cholangiocarcinoma, pancreatic adenocarcinoma, and periampullary carcinomas. Rare causes include biliary inflammatory pseudotumor, gallbladder carcinoma, hepatocellular carcinoma, metastases to bile ducts, and extrinsic bile duct compression secondary to periportal or peripancreatic lymphadenopathy. Contrast material-enhanced magnetic resonance (MR) imaging with MR cholangiopancreatography is extremely helpful in the noninvasive evaluation of patients with obstructive jaundice, an obstructive pattern of liver function, or incidentally detected biliary duct dilatation. Some of these conditions may show characteristic findings at MR imaging-MR cholangiopancreatography that help in making a definitive diagnosis. Although endoscopic retrograde cholangiopancreatography with tissue biopsy or surgery is needed for the definitive diagnosis of many of these strictures, certain MR imaging characteristics of the narrowed segment (eg, thickened wall, long-segment involvement, asymmetry, indistinct outer margin, luminal irregularity, hyperenhancement relative to the liver parenchyma) may favor a malignant cause. Awareness of the various causes of bile duct strictures in adults and familiarity with their appearances at MR imaging-MR cholangiopancreatography are important for accurate diagnosis and optimal patient management.

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.

Relapse of IgG4-related sclerosing cholangitis after steroid therapy: image findings and risk factors

OBJECTIVES

To compare imaging data from IgG4-related sclerosing cholangitis (IgG4-SC) obtained at initial attack and at relapse, and to determine risk factors predicting relapse of IgG4-SC after steroid therapy.

METHODS

Twenty-three patients with relapsed IgG4-SC and 36 non-relapsed patients were included. Computed tomography, magnetic resonance cholangiography, and endoscopic retrograde cholangiography were used to determine biliary and extrabiliary involvement. Images taken at the time of the initial attack were compared with those taken at relapse. Risk factors were determined by comparing clinical and imaging factors in the relapse and non-relapse groups.

RESULTS

In comparison to the initial attack, relapsed IgG4-SC was characterised by more frequent extrapancreatic and multiple bile duct strictures, increased bile duct segment involvement, thicker bile duct walls, and a less frequent association with autoimmune pancreatitis (AIP) (P ≤ 0.016). Compared with non-relapse, relapse was significantly associated with less frequent use of maintenance steroid therapy, more frequent extrapancreatic and multiple bile duct strictures, increased bile duct segment involvement, and thicker bile duct walls during the initial attack (P ≤ 0.021).

CONCLUSIONS

Relapsed IgG4-SC presented with a more aggressive appearance on imaging than the initial attack. The degree of bile duct involvement and use of maintenance steroid therapy were associated with relapse of IgG4-SC.

Diagnosis and classification of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic disease of the liver and that is characterized by progressive inflammation, fibrosis, and stricturing of the intrahepatic and extrahepatic bile ducts. It is progressive in most patients and leads to cirrhosis. It is a rare disease, mostly affecting people of northern European descent, males greater than females. The diagnosis is best established by contrast cholangiography, which reveals a characteristic picture of diffuse, multifocal strictures and focal dilation of the bile ducts, leading to a beaded appearance. Inflammatory bowel disease (IBD) is present in ~75% of the patients with PSC, mostly ulcerative colitis (~85% of the cases). In addition to biliary cirrhosis, complications of PSC include dominant strictures of the bile ducts, cholangitis, cholangiocarcinoma, colon dysplasia and cancer in patients with IBD, gallbladder polyps and cancer, and hepatic osteodystrophy. The etiology of PSC is not clear, but studies are ongoing. The median survival without liver transplantation is 12 to 15 years after diagnosis. Currently there are no effective treatments except liver transplantation. Immunosuppressive medications have not been shown to be effective but antibiotics and anti-fibrotic agents seem promising.

Sclerosing cholangitis with autoimmune pancreatitis versus primary sclerosing cholangitis: comparison on endoscopic retrograde cholangiography, MR cholangiography, CT, and MRI

BACKGROUND

It is essential to differentiate sclerosing cholangitis with autoimmune pancreatitis (SC-AIP) from primary sclerosing cholangitis (PSC) as the treatment and prognosis of the two diseases are totally different.

PURPOSE

To compare image findings of SC-AIP and PSC on endoscopic retrograde cholangiography (ERC), magnetic resonance cholangiography (MRC), computed tomography (CT), and magnetic resonance imaging (MRI).

MATERIAL AND METHODS

Two radiologists retrospectively reviewed ERC, MRC, CT, and MRI in 28 SC-AIP and 23 PSC patients in consensus. Factors evaluated included the length, location, and multiplicity of bile duct stricture, the presence of characteristic cholangiographic features of PSC on ERC and MRC, and the presence, location, thickness, and pattern of bile duct wall thickening on CT and MRI.

RESULTS

On ERC, focal stricture, multifocal and intrahepatic bile duct stricture, and beaded, pruned-tree, and diverticulum-like appearance were more frequent in PSC than in SC-AIP patients (P ≤ 0.006). On MRC, multifocal and intrahepatic bile duct stricture and pruned-tree appearance were more frequent in PSC than in SC-AIP patients (P ≤ 0.044). On CT and MRI, the bile duct wall was thicker (5.1 mm vs. 3.1 mm; P = 0.033 and 4.3 mm vs. 3.0 mm; P = 0.01, respectively) in SC-AIP than in PSC patients. PSC was more frequently associated with intrahepatic bile duct wall thickening on both CT (93% vs. 50%; P = 0.024) and MRI (100% vs. 50%; P = 0.023) than SC-AIP.

CONCLUSION

The combination of ERC or MRC with cross-sectional images, including CT and MRI, may be helpful in differentiating between SC-AIP and PSC.

MRI of the pancreas: problem solving tool

Advances in MR hardware and pulse sequence design over the years have improved the quality and robustness of MR imaging of the pancreas. Today, MRI is an indispensible tool for studying the pancreas and can provide useful information not attainable with other noninvasive or minimally invasive imaging techniques. In the present review, specific cases are reviewed where the strengths of MRI demonstrate the utility of this imaging modality as a problem solving tool.

Ultrasonographic findings of extrapancreatic lesions associated with autoimmune pancreatitis

AIM: To summarize ultrasononographic findings of extrapancreatic lesions associated with autoimmune pancreatitis (AIP).

METHODS: Sixteen patients with AIP underwent ultrasound examination of the pancreatic duct, bile duct, gall bladder, peripancreatic lymph nodes, kidneys, parotid glands, submandibular glands, and lacrimal glands to observe whether the pancreatic duct and bile duct were dilated, the gall bladder wall was thickened, parapancreatic lymph nodes were enlarged, echoes of the kidneys were evenly distributed, and the parotid glands, submandibular glands and lacrimal glands mimicked symptoms associated with Sjogren's syndrome.

RESULTS: Of 16 patients, 6 had dilated pancreatic ducts, 8 had dilated bile ducts, 6 had thickening of the gall bladder wall, and 3 had enlarged peripancreatic lymph nodes. Of 10 patients who underwent examination of the parotid glands, submandibular glands, and lacrimal glands, one had abnormalities in the parotid glands, 3 in the submandibular glands, and 7 in the lacrimal glands.

CONCLUSION: Lacrimal gland abnormalities occur more usually in AIP patients, which may be useful for the differentiation of AIP from pancreatic cancer.

Atypical manifestations of IgG4-related sclerosing disease in the abdomen: imaging findings and pathologic correlations

OBJECTIVE

The purpose of this essay is to illustrate a variety of atypical imaging manifestations of IgG4-related sclerosing disease in the abdomen and to correlate the imaging and pathologic findings.

CONCLUSION

In rare instances, IgG4-related sclerosing disease manifests atypical features in various organs in the abdomen. It is important that radiologists be aware of the typical and atypical features of this disease to provide timely effective treatment.

Peripancreatic vascular involvements of autoimmune pancreatitis

BACKGROUND AND AIM

Although peripancreatic vascular lesions are occasionally encountered in autoimmune pancreatitis (AIP), there are few reports focusing on these involvements. We aimed to investigate the peripancreatic vascular involvements associated with AIP.

METHODS

We retrospectively analyzed 54 AIP patients who met the International Consensus Diagnostic Criteria for AIP between July 2003 and October 2010. All of the 54 patients were subjected to multiphasic multidetector computed tomography, and the prevalence, location and prognosis of peripancreatic vascular involvements were investigated.

RESULTS

Of the 54 AIP patients, 24 (44.4%) exhibited involvements in the form of peripancreatic vascular lesions (stenoses of the splenic vein in 22 and of the superior mesenteric-portal vein in 13, development of perigastric collateral circulation in 18, gastric varices with a red color sign in one and thrombosis inside the portal vein in one). Diffuse-type AIP was associated with a significantly higher prevalence of vascular involvements compared with focal-type AIP (P = 0.033). A total of 14 out of 16 patients who underwent corticosteroid treatment showed improvement in vascular lesions. One case followed up without corticosteroid treatment and presenting an obstruction of the splenic vein exhibited involvements in the form of an infarction and hemorrhagic cysts of the spleen and ultimately underwent distal pancreatectomy and splenectomy.

CONCLUSIONS

Autoimmune pancreatitis patients show a high prevalence of peripancreatic vascular involvements. Thus, patients with vascular involvements are suitable candidates for steroid therapy with evaluation of its potential merits and demerits, even if they are asymptomatic.

Differential diagnosis of sclerosing cholangitis with autoimmune pancreatitis and periductal infiltrating cancer in the common bile duct at dynamic CT, endoscopic retrograde cholangiography and MR cholangiography

OBJECTIVES

To compare findings at dynamic computed tomography (CT), endoscopic retrograde cholangiography (ERC) and magnetic resonance cholangiography (MRC) in patients with sclerosing cholangitis with autoimmune pancreatitis (SC-AIP) and periductal infiltrating cancer in the common bile duct (CBD), and to evaluate the diagnostic performance of ERC and MRC in differentiating between the two diseases.

METHODS

Bile duct changes at dynamic CT, ERC and MRC were compared in 58 patients with SC-AIP and CBD involvement and 93 patients with periductal infiltrating CBD cancer. Two radiologists rated their confidence in differentiating between the two diseases and the diagnostic performances of ERC and MRC were compared.

RESULTS

At CT, SC-AIP was more frequently associated with intrapancreatic CBD involvement, thinner CBD walls, concentric wall thickening, smooth outer margins, and lower degrees of upstream ductal dilatation and contrast enhancement (P ≤ 0.05) than CBD cancer. At ERC and MRC, SC-AIP was more frequently associated with smooth margins, gradual and symmetric narrowing, multifocal involvement and hourglass appearance (P ≤ 0.027) than CBD cancer. MRC showed good diagnostic performance comparable to ERC.

CONCLUSIONS

Dynamic CT, ERC and MRC can be helpful in distinguishing SC-AIP from periductal infiltrating CBD cancer. MRC may be a useful diagnostic alternative to ERC in differentiating between the two diseases.

KEY POINTS

• SC-AIP often mimics periductal infiltrating ductal cancer. • Imaging findings of SC-AIP and periductal infiltrating CBD cancer can be similar. • Dynamic CT, ERC and MRC help differentiate between these two diseases. • MRC may be a useful diagnostic alternative to ERC.

Clinical analysis of 36 cases of autoimmune pancreatitis in China

BACKGROUND

To improve the early identification of autoimmune pancreatitis in China by a retrospective analysis of clinical data from AIP patients.

METHODOLOGY/PRINCIPAL FINDINGS

The analysis included 36 patients admitted by the surgery department of our hospital from January 2003 to October 2011 whose postoperative pathological confirmations were consistent with the histological criteria of Honolulu Consensus Document. The clinical phenotypes associated with the histopathologic patterns of LPSP and IDCP were referred to as type 1 and type 2 of AIP, respectively. A retrospective analysis of clinical features, serological data, pathological findings and imageological records was performed in line with the subtypes of AIP. Type 1 showing a sex predilection (males) was commonly more dominant than type 2 in all AIP. Type 2 without a gender predilection was, on average, a decade younger than type 1. Type 1 was inferior to type 2 in ALT, ALP and γ-GT with statistical significance (P = 0.044, 0.025 and 0.013). Type 1 was inferior to type 2 in AST with difference close to statistical significance (P = 0.072). Histopathology revealed frequent lymphoplasmacytic infiltration with less frequent infiltration of neutrophils, eosinophils and fibroblasts. Diffuse and intensive interstitial fibrosis could be seen. The changes of pancreatic head were more frequently seen in type 2 than in type 1 (P = 0.05). Plasma cells staining of IgG4 at a density of over 30 or more cells per high-power field appeared to be a specific finding in China with type 1. Imageology found a diffusely or focally enlarged pancreas, most frequently a mass or enlargement in the pancreatic head, characteristic capsule-like rim, calcification or pancreatic calculus and cystic degeneration.

CONCLUSIONS/SIGNIFICANCE

AIP is a unique type of chronic pancreatitis and has distinctive serological, pathological and imageological characteristics, which should be used for differentiation from pancreatic cancer.

Distinguishing autoimmune pancreatitis from pancreaticobiliary cancers: current strategy

OBJECTIVE

A review of the literature to identify current modalities for the diagnosis of autoimmune pancreatitis (AIP) with the objective of establishing a strategy to distinguish it from pancreaticobiliary cancers.

BACKGROUND

Pancreatic and biliary manifestations of AIP mimic pancreaticobiliary cancers. Misdiagnosis of AIP can result in major surgery for a steroid-responsive disease.

METHODS

A review of the literature was performed to identify recent advances in the diagnosis of AIP and evaluate outcomes with various diagnostic strategies to minimize operative intervention for an autoimmune disease.

RESULTS

Diagnostic criteria for AIP are based on histology, imaging, serology, extrapancreatic organ involvement, and response to steroid therapy. The most commonly involved extrapancreatic sites are bile duct, kidney, and retroperitoneum. The Mayo Clinic diagnostic strategy utilizes core biopsy of the pancreas and the Japanese strategy depends on a characteristic pancreatogram. The rate of operative intervention was similar with both strategies and none of the patients with cancer received steroid therapy. Immunoglobulin G subtype 4 (IgG4)-associated cholangitis mimics cholangiocarcinoma and presence of more than 10 IgG4-positive plasma cells/high power field on endoscopic biopsy of the bile duct was diagnostic for AIP in 88% patients. Biliary complications and early relapse are common after surgical resection and immunomodulatory drugs can maintain long-term remission.

CONCLUSION

Criteria based on histology, imaging, endoscopy, serology, extrapancreatic organ involvement, and response to steroid therapy improve the diagnostic yield for AIP. Application of diagnostic and therapeutic protocols by a multidisciplinary team will optimize outcomes with a decline in the rate of operative intervention for AIP, a steroid-responsive disease with propensity for relapse.

Strategy to differentiate autoimmune pancreatitis from pancreas cancer

Autoimmune pancreatitis (AIP) is a newly described entity of pancreatitis in which the pathogenesis appears to involve autoimmune mechanisms. Based on histological and immunohistochemical examinations of various organs of AIP patients, AIP appears to be a pancreatic lesion reflecting a systemic “IgG4-related sclerosing disease”. Clinically, AIP patients and patients with pancreatic cancer share many features, such as preponderance of elderly males, frequent initial symptom of painless jaundice, development of new-onset diabetes mellitus, and elevated levels of serum tumor markers. It is of uppermost importance not to misdiagnose AIP as pancreatic cancer. Since there is currently no diagnostic serological marker for AIP, and approach to the pancreas for histological examination is generally difficult, AIP is diagnosed using a combination of clinical, serological, morphological, and histopathological features. Findings suggesting AIP rather than pancreatic cancer include: fluctuating obstructive jaundice; elevated serum IgG4 levels; diffuse enlargement of the pancreas; delayed enhancement of the enlarged pancreas and presence of a capsule-like rim on dynamic computed tomography; low apparent diffusion coefficient values on diffusion-weighted magnetic resonance image; irregular narrowing of the main pancreatic duct on endoscopic retrograde cholangiopancreatography; less upstream dilatation of the main pancreatic duct on magnetic resonance cholangiopancreatography, presence of other organ involvement such as bilateral salivary gland swelling, retroperitoneal fibrosis and hilar or intrahepatic sclerosing cholangitis; negative work-up for malignancy including endoscopic ultrasound-guided fine needle aspiration; and steroid responsiveness. Since AIP responds dramatically to steroid therapy, accurate diagnosis of AIP can avoid unnecessary laparotomy or pancreatic resection.

IgG4-related sclerosing disease: autoimmune pancreatitis and extrapancreatic manifestations

Autoimmune pancreatitis is the pancreatic manifestation of IgG4-related sclerosing disease, which recently was recognized as a distinct disease entity. Numerous extrapancreatic organs, such as the bile ducts, gallbladder, kidneys, retroperitoneum, thyroid, salivary glands, lung, mediastinum, lymph nodes, and prostate may be involved, either synchronously or metachronously. Most cases of autoimmune pancreatitis are associated with elevated serum IgG4 levels; extensive IgG4-positive plasma cells; and infiltration of lymphocytes into various organs, which leads to fibrosis. There are several established diagnostic criteria systems that are used to diagnose autoimmune pancreatitis and that rely on a combination of imaging findings of the pancreas and other organs, serologic findings, pancreatic histologic findings, and response to corticosteroid therapy. It is important to recognize multiorgan involvement of IgG4-related sclerosing disease and be familiar with its clinical and imaging features because it demonstrates a favorable response to treatment.

A case of IgG4-related disease with rectal cancer

A 72-year-old male with liver dysfunction and an increase in serum total protein/albumin (TP/Alb) ratio was referred to our hospital. There was a marked increase in serum immunoglobulin (Ig) G4 level (IgG/IgG4: 3,485/2,860 mg/dl). Diagnostic imaging did not reveal any enlargement of the pancreas or narrowing of the pancreatic duct. However, bilateral submaxillary gland swelling, sclerosing cholangitis, and retroperitoneal fibrosis were noted, suggesting multifocal fibrosclerosis. Histological examination of the submaxillary gland showed the infiltration of IgG4-positive plasma cells, although there was no narrowing of the pancreatic duct, leading to a diagnosis of IgG4-related disease with various extrapancreatic lesions. Systemic investigation before the introduction of steroid therapy revealed rectal cancer. After low-position anterior resection, steroid therapy was introduced, reducing the lesions. Recent studies have reported autoimmune pancreatitis/IgG4-related disease with malignant tumors. However, the association and pathogenesis remain to be clarified. Malignant tumors are detected before or after the treatment of autoimmune pancreatitis/IgG4-related disease; pretreatment diagnosis and post-treatment follow-up should be carefully performed, bearing in mind the concomitant development of malignant tumors.

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.

Management strategies for autoimmune pancreatitis

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Autoimmune pancreatitis and IgG4-related sclerosing cholangitis

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Serologic issues in IgG4-related systemic disease and autoimmune pancreatitis

PURPOSE OF REVIEW

IgG4-related systemic disease (ISD) is a recently recognized syndrome affecting multiple organs. Autoimmune pancreatitis (AIP) is the pancreatic manifestation of ISD and mimics pancreatic cancer. Current data show frequent association with serum IgG4 elevation and other serologic abnormalities. Here we explore the diagnostic and possible prognostic utility and pathogenetic implications of serologic abnormalities in ISD.

RECENT FINDINGS

Serum IgG4 elevations (>140 mg/dl) are seen in 70-80% of AIP patients and also in 5% of normal population and 10% of pancreatic cancer making it an unsuitable single marker for diagnosis. However, when combined with other features of AIP, it can be of great diagnostic value though its utility in monitoring of therapy or as a marker or predictor of relapse is limited. Several other antibodies have been identified in AIP against pancreas-specific antigens like trypsinogens I and II, pancreatic secretory trypsin inhibitor (PSTI) and plasminogen binding protein (PBP) and other nonpancreas-specific antigens. Anti-PBP antibodies appear to have potential diagnostic utility but require further validation.

SUMMARY

No single serologic marker is diagnostic of ISD. Serum IgG4 elevation has convincing diagnostic utility when combined with other disease features although its value in disease monitoring may be limited.

Analysis of regulatory T cells and IgG4-positive plasma cells among patients of IgG4-related sclerosing cholangitis and autoimmune liver diseases

OBJECTIVES

Patients with autoimmune pancreatitis (AIP) characteristically show elevated serum levels of immunoglobulin G4 (IgG4) and abundant infiltration of IgG4-positive plasmacytes in the involved organs. The most common involved organ showing extrapancreatic lesions is the bile duct, which exhibits sclerosing cholangitis (SC). However, the role of IgG4 in the development of IgG4-related SC (IgG4-SC) remains unclear. To clarify the role of IgG4 in IgG4-SC, we have performed an immunohistochemical analysis of the bile duct.

METHODS

Laboratory and immunohistochemical findings of liver biopsy specimens obtained from patients with IgG4-SC, primary sclerosing cholangitis (PSC), autoimmune hepatitis (AIH), and primary biliary cirrhosis (PBC) were compared. The biopsy specimens were first stained with anti-IgG1, anti-IgG4, and anti-Foxp3 (forkhead box P3) antibodies, and the ratio of IgG4-, IgG1-, and Foxp3-positive cells, respectively, to infiltrated mononuclear cells (IgG4/Mono, IgG1/Mono, Foxp3/Mono) was assessed.

RESULTS

The ratio of IgG4/IgG1-positive plasma cells was significantly higher in specimens obtained from patients with IgG4-SC than in those from patients with PSC, AIH, and PBC. The Foxp3/Mono ratio in patients with PBC was significantly higher than that in patients with IgG4-SC and PSC. In patients with IgG4-SC, the number of Foxp3-positive cells was significantly correlated with the number of IgG4-positive cells; in the other patient groups, there was no correlation.

CONCLUSIONS

The IgG4/IgG1 ratio in the liver may be a useful marker for differential diagnosis of IgG4-SC and PSC. In IgG4-SC, abundant infiltration of regulatory T cells (Tregs) may affect the switching of B cells to IgG4-producing plasmacytes, and there is a possibility that the function of Tregs is different in IgG4-SC and other liver diseases (PSC, AIH, and PBC).

Autoimmune pancreatitis and IgG4-related sclerosing disease

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

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.

Comparison of sclerosing cholangitis with autoimmune pancreatitis and infiltrative extrahepatic cholangiocarcinoma: multidetector-row computed tomography findings

PURPOSE

The aim of this study was to compare multidetector-row computed tomography (MDCT) findings between cases of sclerosing cholangitis with autoimmune pancreatitis (SC-AIP) and infiltrative extrahepatic cholangiocarcinoma (IEC).

MATERIALS AND METHODS

We retrospectively assessed MDCT findings from 16 IEC cases and 13 SC-AIP cases. MDCT findings were analyzed with regard to location, length, wall thickness, contour, stricture wall enhancement pattern, proximal duct diameter, and the presence of diffuse concentric thickening in the proximal duct and gallbladder wall thickness.

RESULTS

Stricture length, stricture wall thickness, and proximal duct diameter were significantly smaller for SC-AIP than for IEC: 19.3 +/- 8.7 vs. 31.8 +/- 12.0 mm (P = 0.004), 2.1 +/- 1.3 vs. 4.1 +/- 1.3 mm (P < 0.001), and 9.2 +/- 3.9 vs. 13.3 +/- 5.0 mm (P = 0.012), respectively. SC-AIP was correlated with stricture location in both the intrapancreatic and hilar hepatic bile ducts, concentric stricture contour (P < 0.001), and diffuse concentric thickening of the proximal bile duct (P = 0.010). Overall values of sensitivity, specificity, and accuracy used to distinguish between SC-AIP and IEC for stricture wall thickness of <3.0 mm and concentric contour were 76.9%, 93.8%, and 86.2%, respectively, and 100%, 87.5%, 93.1%, respectively.

CONCLUSION

Concentric contour and stricture wall thicknesses of <3.0 mm may help distinguish between SC-AIP and IEC.

Primary sclerosing cholangitis with elevated serum IgG4 levels and/or infiltration of abundant IgG4-positive plasma cells

Immunoglobin G4-related sclerosing cholangitis (IgG4-SC) is recognized as one of the systemic sclerosing diseases characterized by abundant IgG4-positive plasma cells with effective steroid therapy. On the other hand, primary sclerosing cholangitis (PSC), recognized as a sclerosing cholangitis of unknown origin without steroid efficacy, has been often clinically confused with IgG4-SC. To date, the prognosis of IgG4-SC is unclear, while the prognosis of PSC is well known to be poor. Therefore, it is clinically very important to be able to distinguish IgG4-SC from PSC. However, at the present time it still remains unclear whether PSC may sometimes be misdiagnosed as IgG4-SC or not. Herein, we report three rare cases of PSC with elevated serum IgG4 levels and/or an infiltration of abundant IgG4-positive plasma cells in the liver: a young male with ulcerative colitis (UC), and elderly female and a young female, each with elevated serum IgG4 levels. The first two patients showed infiltration of abundant IgG4-positive plasma cells in the portal area of the liver without response to steroid therapy. From our experiences, we emphasize that some patients with PSC, who do not respond to steroid therapy, show elevated serum IgG4 levels and/or infiltration of abundant IgG4-positive plasma cells, although the mechanism still remains unclear.

Autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis (AIP) is a relatively newly recognized type of pancreatitis that is characterized by diffuse or focal swelling of the pancreas due to lymphoplasmacytic infiltration and fibrosis of the pancreatic parenchyma.

MATERIAL AND METHODS

A PubMed literature search was performed using the keywords "autoimmune pancreatitis". Sometimes, bibliographies were cross-referenced and related article searches were performed once an article of interest was identified.

RESULTS

Pathologically, AIP shows narrowing of the pancreatic ducts and the intrapancreatic portion of the common bile duct. Obstructive jaundice is a common symptom at presentation, and pancreatic cancer represents an important clinical differential diagnosis. In late stages of the disease, the normal pancreatic parenchyma is often replaced by large amounts of fibrosis. Histologically, there seem to be two subtypes of the disease-one showing infiltration with IgG4-positive plasma cells but lacking granulocytic epithelial lesions (GELs), the other showing GELs but lacking strong IgG4 positivity. AIP is in at least some instances the pancreatic manifestation of a clinicopathological entity of IgG4-related systemic sclerosing disease. On the basis of pancreatic imaging, together with serological measurement of IgG4 and evaluation of other organ involvement, many AIP patients can be identified. The remaining patients require further diagnostic work-up. In these patients, pancreatic core needle biopsy and, as AIP responds to steroid treatment, also a trial with steroids, can help to differentiate AIP from pancreatic cancer. OUTLOOK AND DISCUSSION: This review presents the pathological, radiologic and laboratory findings of AIP. Moreover, the treatment and pathogenesis are discussed.

Clinical significance of extrapancreatic lesions in autoimmune pancreatitis

OBJECTIVES

To clarify the frequency and clinical significance of extrapancreatic lesions in autoimmune pancreatitis (AIP).

METHODS

The frequency and clinical characteristics of extrapancreatic lesions during the clinical course of AIP were investigated retrospectively in 64 patients with AIP. The predictive factors for relapse of AIP at clinical onset were also examined.

RESULTS

Extrapancreatic lesions occurred in 95% (61/64) during the clinical course of AIP. The frequencies of sclerosing cholangitis, sclerosing sialadenitis, retroperitoneal fibrosis, and mediastinal or hilar lymphadenopathy were 84% (54/64), 23% (15/64), 16% (10/64), and 77% (27/35), respectively. Patients with sclerosing sialadenitis or extrapancreatic bile duct sclerosing cholangitis had a significantly higher serum immunoglobulin G concentration than those without (P = 0.005 and P = 0.016, respectively). Univariate analysis revealed that sclerosing sialadenitis (P = 0.005), diffuse pancreatic ductal changes (P = 0.028), and a high serum immunoglobulin G concentration (P = 0.030) at clinical onset of AIP were significant predictive factors for relapse. Multivariate analysis revealed that diffuse pancreatic ductal changes (P = 0.005) and sclerosing sialadenitis (P = 0.012) were significant independent predictive factors for relapse of AIP.

CONCLUSIONS

The frequency of extrapancreatic lesions with AIP during the clinical course was high. The presence of sclerosing sialadenitis at clinical onset is a significant predictive factor for relapse of AIP.

Metachronous extrapancreatic lesions in autoimmune pancreatitis

OBJECTIVE

Autoimmune pancreatitis (AIP) is frequently associated with various extrapancreatic lesions. The distribution and frequency of extrapancreatic lesions preceding or subsequent to AIP are unknown. The aim of this study was to investigate metachronous extrapancreatic lesions of AIP.

PATIENTS AND METHODS

Extrapancreatic lesions were examined clinically, radiologically, and histologically in 56 AIP patients.

RESULTS

Extrapancreatic lesions were associated in 25 (45%) of 56 AIP patients. Twenty-nine extrapancreatic lesions were detected synchronously with AIP in 18 patients, and 18 lesions were detected metachronously in 11 AIP patients. Fourteen patients had more than 2 extrapancreatic lesions. There was no significant difference in serum IgG4 levels between AIP patients with preceding extrapancreatic lesions and synchronous extrapancreatic lesions. Extrapancreatic lesions preceding AIP were sclerosing sialadenitis (n=8), cervical lymphadenopathy (n=4), swelling of the lacrimal glands (n=2), retroperitoneal fibrosis (n=1), and hilar lymphadenopathy (n=1). Retrospective histopathological examination confirmed that these lesions were compatible with IgG4-related sclerosing disease. Steroid therapy was not given for these initial lesions, and AIP occurred 3 to 48 months after these initial lesions. Swelling of the preceding extrapancreatic lesions persisted when AIP occurred. Extrapancreatic lesions subsequent to AIP were retroperitoneal fibrosis (n=1) and systemic lymphadenopathy (n=1), both of which occurred during follow-up of AIP without steroid therapy. All extrapancreatic lesions improved after steroid therapy.

CONCLUSION

Swelling of salivary or lacrimal glands, lymphadenopathy, and retroperitoneal fibrosis can precede AIP. Lymphadenopathy and retroperitoneal fibrosis can occur subsequent to AIP. Recognition of these findings will aid in the correct diagnosis of AIP.

Allergic manifestations in autoimmune pancreatitis

OBJECTIVE

Autoimmune pancreatitis (AIP) is a peculiar type of pancreatitis of presumed autoimmune etiology. However, target antigens for AIP have not been detected. Furthermore, its preponderant occurrence in elderly men and the very dramatic response with no major residual deformity to oral steroid therapy within 2 weeks suggest that the pathogenesis of AIP might not involve autoimmune mechanism. Recently, it was reported that the immune reaction closely involved in the pathogenesis of allergic disorders was upregulated in the affected tissues of AIP. This study aimed to examine the allergic manifestations in AIP patients.

METHODS

This case series consisted of 45 AIP patients. Present and/or past histories of allergic diseases, clinical findings, and laboratory data were reviewed.

RESULTS

Twenty patients (allergic-type AIP) had histories of allergic diseases, such as acute allergic rhinitis (n= 11), including rose and hay fever, atopic dermatitis (n= 5), bronchial asthma (n= 3), drug allergy (n= 2), and hypersensitivity pneumonitis (n= 1). Serum IgE levels were elevated in only 12 allergic-type AIP patients, and they were significantly higher in allergic-type AIP patients than in AIP patients without allergic manifestations (P = 0.0001). The peripheral eosinophil count was significantly elevated in allergic-type AIP patients (P =0.048). With respect to initial symptoms, obstructive jaundice was less frequent in allergic-type AIP patients (P = 0.012), and abdominal pain was detected in only five patients with allergic-type AIP (P = 0.013). Allergic-type AIP occurred predominantly from September to February in 19 of 20 patients (P = 0.001).

CONCLUSION

Allergic manifestations were detected in about half of the AIP patients, and allergic mechanisms may be related to the occurrence of AIP in these patients.

Usefulness of positron emission tomography in the evaluation of distribution and activity of systemic lesions associated with autoimmune pancreatitis

BACKGROUND/AIMS

Autoimmune pancreatitis (AIP) is an IgG4-related systemic disease often accompanied with a variety of lesions outside of the pancreas and is treated with steroid therapy. The aim of this study is to analyze the usefulness of positron emission tomography with (18)F-fluorodeoxyglucose (FDG-PET) in the evaluation of distribution and activity of systemic lesions of AIP during steroid therapy.

METHODS

Eleven cases of AIP had their FDG-PET images evaluated before and 3 months after steroid therapy and another 2 cases only before therapy. AIP activity was determined by the level of serum markers, IgG and IgG4, and compared with findings of PET.

RESULTS

In all 13 cases of AIP, a moderate to intense level of FDG accumulation was recognized in the pancreatic lesion before steroid therapy. Of 13 patients, 11 (84.6%) showed FDG accumulation in the multiple organs, such as mediastinal and other lymph nodes, salivary gland, biliary tract, prostate, and aortic wall. In 11 patients who underwent PET before and after steroid therapy, FDG accumulation was diminished in almost all systemic lesions, with a mean of maximum standardized uptake value (SUV(max)) in the pancreatic lesion from 5.12 to 2.69. Similar to the SUV level, serum IgG and IgG4 were decreased in most of the cases after steroid therapy.

CONCLUSIONS

FDG-PET is an effective modality to evaluate the response of steroid therapy and the distribution and activity of various systemic lesions of AIP.

A case of tubulointerstitial nephritis in IgG4-related systemic disease with markedly enlarged kidneys

IgG4-related systemic disease, including autoimmune pancreatitis, is a multi-organ disorder characterized by elevated serum immunoglobulin G4 (IgG4) concentration and IgG4-positive plasma cell infiltration. We report the case of a 67-year-old man with IgG4-related tubulointerstitial nephritis, presenting with markedly enlarged kidneys and renal dysfunction. The serum IgG4 level was elevated with 4200 mg/dl and pathological examination revealed patchy, clearly fringed areas of IgG4-positive plasma cell infiltration and advanced fibrosis in the renal parenchyma, perirenal tissue and lymph nodes. With oral prednisolone at a dose of 60 mg daily, a contraction of the kidneys and an improvement of renal function were observed. No recurrence of the disease was observed during the reduction of prednisolone to 2 mg daily over 4 years.

Autoimmune pancreatitis: pancreatic and extrapancreatic imaging findings

OBJECTIVE

The purpose of this article is to discuss the systemic nature of autoimmune pancreatitis and its various pancreatic and extrapancreatic imaging findings.

CONCLUSION

Autoimmune pancreatitis is a systemic disease with a wide range of pancreatic and extrapancreatic imaging findings. These findings can mimic those of other diseases in the pancreas or other organs and therefore are commonly misdiagnosed and mistreated. It is important for radiologists to understand both the pancreatic and extrapancreatic imaging findings of autoimmune pancreatitis to make accurate and timely diagnoses.

Autoimmune pancreatitis and IgG4-associated sclerosing cholangitis

Autoimmune pancreatitis (AIP) is a unique form of chronic pancreatitis characterised by a high serum IgG4 concentration and complications that include various extrapancreatic manifestations, one of which is sclerosing cholangitis. In AIP patients, infiltration of abundant IgG4-positive plasma cells and dense fibrosis are commonly observed in the pancreas and wall of the bile duct and gallbladder. The major symptom at onset of AIP is obstructive jaundice caused by stricture of the bile duct, and this requires differential diagnosis of AIP from pancreato-biliary malignancies and primary sclerosing cholangitis (PSC). Recently, there have been reports of particular cases of sclerosing cholangitis with a high serum IgG4 level and cholangiographic and pathological findings comparable to those observed in AIP patients. Being apparently different from PSC and similar to that in AIP, sclerosing cholangitis with and without AIP shows a clinical response to steroid therapy and thus is designated as 'IgG4-associated sclerosing cholangitis'. The pathogenesis of AIP and IgG4-associated sclerosing cholangitis remains at yet undetermined.

Serum IgG4 levels and extrapancreatic lesions in autoimmune pancreatitis

OBJECTIVE

Serum IgG4 levels are frequently elevated in patients with autoimmune pancreatitis (AIP). AIP is sometimes associated with various extrapancreatic lesions. This study examined whether there is a correlation between serum IgG4 levels and associated extrapancreatic lesions in AIP patients.

METHODS

Serum IgG4 levels were measured in 40 AIP patients before therapy. In these patients, four associated extrapancreatic lesions (sclerosing cholangitis, sclerosing cholecystitis, sclerosing sialadenitis, and retroperitoneal fibrosis) and clinical factors, such as age, sex ratio, enlargement of the pancreas, and initial symptoms, were retrospectively assessed.

RESULTS

The mean serum IgG4 level of the 40 AIP patients was 411+/-448 mg/dl. On the basis of the receiver operator characteristic curve data, the optimal cutoff value for the serum IgG4 to distinguish between AIP patients with and without extrapancreatic lesions was 220 mg/dl; 18 (78%) of 23 patients whose serum IgG4 was more than or equal to 220 mg/dl had extrapancreatic lesions, whereas four (24%) of 17 patients whose serum IgG4 was less than 220 mg/dl had extrapancreatic lesions (P=0.0011). No significant differences between the two groups in age, sex, the frequency of pancreatic enlargement or obstructive jaundice, and associated sialadenitis, retroperitoneal fibrosis, and diabetes mellitus were identified. Sclerosing cholangitis and cholecystitis were more frequent in patients with serum IgG4 levels of more than or equal to 220 mg/dl than in those with a lower serum IgG4 level (P=0.0002 and 0.0204, respectively). The number of associated extrapancreatic lesions was significantly greater in patients with a high-serum IgG4 level.

CONCLUSION

AIP patients with serum IgG4 levels of more than or equal to 220 mg/dl frequently have extrapancreatic lesions.

Ultrasonographic imaging of bile duct lesions in autoimmune pancreatitis

OBJECTIVES

Patients with autoimmune pancreatitis (AIP) commonly have lesions in the bile duct itself and show stenosis of the bile duct system; however, no detailed study has evaluated the ultrasonographic findings of bile duct lesions in AIP. In this study, we monitored the clinical course and imaging findings, mainly ultrasonographic, of bile duct lesions in AIP.

METHODS

We retrospectively analyzed the incidence of bile duct lesions, imaging findings, and clinical course in 37 patients with AIP.

RESULTS

Characteristic bile duct and gallbladder wall thickening was recognized on ultrasound in 37.8% (14/37) of AIP patients. We divided the patients into 2 types according to the ultrasonographic findings of bile duct wall thickening: (1) 3-layer type (64.3%) and (2) parenchymal-echo type (35.7%). All 14 cases were treated with prednisolone, with immediate resolution of the bile duct lesions.

CONCLUSION

Sclerosing cholangitis is one of the extrapancreatic lesions that are commonly detected in AIP patients; it is detected on ultrasonographic imaging as characteristic wall thickening. Our ultrasonographic findings reflect the fact that bile duct wall thickening in AIP is an inflammatory process that responds to prednisolone therapy. Ultrasonography is a useful tool in detecting biliary tract lesions in AIP.