International consensus diagnostic criteria for autoimmune pancreatitis: guidelines of the International Association of Pancreatology

Clinical and pathological differences between serum immunoglobulin G4-positive and -negative type 1 autoimmune pancreatitis

AIM: To identify clinical and pathological differences between serum immunoglobulin G4 (IgG4)-positive (SIP) and IgG4-negative (SIN) type 1 autoimmune pancreatitis (AIP) in South Korea.

METHODS: AIP was diagnosed by the international consensus diagnostic criteria. The medical records and pathology were retrospectively reviewed and IgG4-positive cells were counted in a high power field (HPF). Type I AIP was defined as a high serum level of IgG4 or histological finding. SIN type 1 AIP was defined as a histological evidence of type 1 AIP and a normal serum IgG4 level. The clinical and pathological findings were compared between the two groups. The analysis was performed using Student’s t test, Fischer’s exact test and Mann-Whitney’s U test. A P value of < 0.05 was considered statistically significant. As repeated comparison was made, P values of less than 5% (P < 0.05) were considered significant.

RESULTS: Twenty five patients with definite type 1 AIP (19 histologically and six serologically diagnosed cases) were enrolled. The mean tissue IgG4 concentrations were significantly higher in SIP than SIN group (40 cells per HPF vs 18 cells per HPF, P = 0.02). Among eight SIN patients, the tissue IgG4 concentrations were less than 15 cells per HPF in most of cases, except one. The sensitivity of serum IgG4 was 68% (17 SIP and eight SIN AIP). Other organ involvement was more frequently associated with SIP than SIN AIP (59% vs 26%, P = 0.016). However, the relapse rate and diffuse swelling of the pancreas were not associated with serum IgG4 level. The concentrations of IgG4-positive cells per HPF were higher in SIP than SIN AIP (40 vs 18, P = 0.02).

CONCLUSION: The sensitivity of serum IgG4 was 68% in type 1 AIP. High serum IgG4 level was associated with other organ involvement and tissue IgG4 concentration but did not affect the relapse rate in type 1 AIP.

Establishment of a serum IgG4 cut-off value for the differential diagnosis of IgG4-related sclerosing cholangitis: a Japanese cohort

BACKGROUND AND AIM

IgG4-related sclerosing cholangitis (IgG4-SC) must be precisely distinguished from primary sclerosing cholangitis and cholangiocarcinoma (CC) because the treatments are completely different. However, the pathological diagnosis of IgG4-SC is difficult. Therefore, highly specific non-invasive criteria such as serum IgG4 should be established. This study established a cut-off for serum IgG4 to differentiate IgG4-SC from respective controls using serum IgG4 levels measured in Japanese centers.

METHODS

A total of 344 IgG4-SC patients were enrolled in this study. As controls, 245, 110, and 149 patients with pancreatic cancer, primary sclerosing cholangitis, and CC, respectively, were enrolled. IgG4-SC patients were classified into three groups: type 1 (stenosis only in the lower part of the common bile duct), type 2 (stenosis diffusely distributed throughout the intrahepatic and extrahepatic bile ducts), and types 3 and 4 (stenosis in the hilar hepatic region) with 246, 56, and 42 patients, respectively. Serum IgG4 levels were compared, and the cut-offs were established.

RESULTS

The cut-off obtained from receiver operator characteristic curves showed similar sensitivity and specificity to that of 135 mg/dL when all IgG4-SC and controls were compared. However, a new cut-off value was established when subgroups of IgG4-SC and controls were compared. A cut-off of 182 mg/dL can increase the specificity to 96.6% (4.7% increase) for distinguishing types 3 and 4 IgG4-SC from CC. A cut-off of 207 mg/dL might be useful for completely distinguishing types 3 and 4 IgG4-SC from all CC.

CONCLUSIONS

Serum IgG4 is useful for the differential diagnosis of IgG4-SC and controls.

Embryological aspects in autoimmune pancreatitis, proposal of autoimmune dorsal pancreatitis

OBJECTIVE

We examined the anatomy of the pancreatic duct system in patients with autoimmune pancreatitis (AIP) from the standpoint of embryological pancreatic primordial.

MATERIAL AND METHODS

The pancreatic duct system involved in 83 AIP patients was embryologically divided into both ventral and dorsal pancreatic ducts (VD type), only the dorsal pancreatic duct (D type), or only the ventral pancreatic duct (V type).

RESULTS

The 83 AIP patients were divided into 62 VD type, 20 D type, and 1 V type. Obstructive jaundice was significantly more frequent in VD type (87%) than in D type (0%; p < 0.01), and abdominal pain was more frequent in D type (24%) than in VD type (2%; p < 0.01). Stenosis of the lower bile duct was detected in 98% of VD type and 15% of D type (p < 0.01). In the 67 patients with involvement of the pancreatic head, only the dorsal pancreatic duct was involved with a normal ventral pancreatic duct in four patients (D type). In the four D-type patients, the pancreatic duct system showed complete pancreas divisum (n = 1), incomplete pancreas divisum (n = 2), or normal pancreatic duct system (n = 1). Stenosis of the lower bile duct was seen in three patients, but was mild, resulting in no obstructive jaundice. Three patients reported abdominal pain and one patient developed acute pancreatitis.

CONCLUSIONS

We propose a new entity of "autoimmune dorsal pancreatitis" in which only the dorsal pancreas is involved, and involvement of the lower bile duct and obstructive jaundice is rare.

Autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a rare, heterogeneous, fibroinflammatory disorder of the pancreas. It has gained increasing recognition due to a presentation that can mimic difficult-to-treat disorders such as pancreatic cancer, cholangiocarcinoma and primary sclerosing cholangitis. In contrast, autoimmune pancreatitis is a benign disease that is very responsive to therapy with corticosteroids. There are two types of AIP. Type 1 disease is the most common worldwide and is associated with extrapancreatic manifestations and elevated levels of IgG4-positive cells. Type 2 AIP is characterized by a paucity of IgG4-positive cells and is more difficult to diagnose. This review provides an update on the diagnosis, pathophysiology and treatment of AIP, with special emphasis on the two subtypes.

The characteristics of ulcerative colitis associated with autoimmune pancreatitis

GOALS

To determine the prevalence of ulcerative colitis (UC) in autoimmune pancreatitis (AIP) patients in a tertiary referral hospital and to compare the clinical and pathologic characteristics and outcomes of UC associated with AIP (AIP-UC) and UC patients.

BACKGROUND

Recently, it was suggested that UC is associated with AIP. However, the prevalence of UC in AIP, together with the clinical characteristics and outcomes of AIP-UC are not clear.

STUDY

We retrospectively reviewed the medical records of AIP patients diagnosed at the Asan Medical Center.

RESULTS

Of the 104 patients with AIP, 6 (5.8%) were also diagnosed with UC. Serum immunoglobulin G (IgG) and IgG4 were elevated in 1 patient (16.7%), respectively, and 4 (66.7%) showed idiopathic duct-centric pancreatitis (type 2 AIP). Compared with 24 matched patients with UC only, AIP-UC patients had a lower body mass index (P=0.003), higher C-reactive protein levels (P=0.048), and higher Mayo scores (P=0.006) at diagnosis of UC. Two AIP-UC patients (33.3%), but none with UC only showed increased infiltration of IgG4-positive cells into the colonic tissues (P=0.006). During follow-up, 2 AIP-UC patients (33.3%) underwent colectomy and 1 (16.7%) died, but no colectomies or deaths occurred in the UC only group.

CONCLUSIONS

AIP patients seem to have a higher risk of UC compared with the general population. The increased IgG4-positive cellular infiltration in the colonic tissue suggests that UC may be an extrapancreatic manifestation of AIP.

18-Fluorodeoxyglucose positron emission tomography does not aid in diagnosis of pancreatic ductal adenocarcinoma

BACKGROUND & AIMS

There are no accurate and reliable tools for diagnosis of early stage pancreatic ductal adenocarcinoma (PDA) or small metastatic lesions. It is also a challenge to differentiate PDA from focal mass-forming pancreatitis (FMP). There is controversy regarding the efficacy of 18-fluorodeoxyglucose positron-emission tomography (FDG-PET) in the diagnosis of PDA. We investigated whether FDG-PET provides information that, combined with data from other imaging techniques, can aid in decision making for patients with suspected PDA.

METHODS

We performed a retrospective analysis of data collected from 232 consecutive patients with suspected PDA at Kobe University Hospital from January 2006 through June 2012. All patients underwent a diagnostic imaging protocol that included multidetector row computed tomography, superparamagnetic iron oxide-enhanced magnetic resonance imaging, and FDG-PET. Based on endoscopic ultrasonography, fine-needle aspiration biopsy, or endoscopic retrograde cholangiopancreatography analyses, 218 patients had PDA (89 underwent resection and 129 did not) and 14 patients had FMP (8 had focal mass-forming chronic pancreatitis and 6 had focal mass-forming autoimmune pancreatitis).

RESULTS

FDG-PET detected 50% of stages 0 and I, 91.9% of stage II, 100% of stage III, and 96.8% of stage IV tumors. Detection was affected significantly by tumor size (P = .024) and T stage (P = .023) in resected tumors. Multidetector row computed tomography detected significantly more liver metastases than FDG-PET. Few para-aortic lymph node or peritoneal metastases were detected by FDG-PET. FDG-PET correctly identified 11 of the 14 patients with FMP (5 of 8 with focal mass-forming chronic pancreatitis and 6 of 6 with focal mass-forming autoimmune pancreatitis).

CONCLUSIONS

FDG-PET is not effective in detecting early stage PDA and small metastases, or in differentiating PDA from FMP. Combining FDG-PET with current diagnostic techniques for PDA did not provide any decisive information, therefore it should not be included in this analysis.

Genetic risk factors for pancreatic disorders

A combination of genetic, environmental, and metabolic factors contribute to the development and recurrence of acute and chronic pancreatitis; information on all of these is required to manage patients effectively. For example, variants that affect regulation of the protease, serine (PRSS)1-PRSS2, and claudin (CLDN)2 loci, rather than their coding sequences, interact with other genetic and environmental factors to affect disease development. New strategies are needed to use these data and determine their contribution to pathogenesis, because these variants differ from previously studied, rare variants in exons (coding regions) of genes such as PRSS1, SPINK1, cystic fibrosis transmembrane conductance regulator (CFTR), chymotrypsin (CTR)C, and calcium-sensing receptor (CASR). Learning how various genetic factors affect pancreatic cells and systems could lead to etiology-based therapies rather than treatment of symptoms.

Models of acute and chronic pancreatitis

Animal models of acute and chronic pancreatitis have been created to examine mechanisms of pathogenesis, test therapeutic interventions, and study the influence of inflammation on the development of pancreatic cancer. In vitro models can be used to study early stage, short-term processes that involve acinar cell responses. Rodent models reproducibly develop mild or severe disease. One of the most commonly used pancreatitis models is created by administration of supraphysiologic concentrations of caerulein, an ortholog of cholecystokinin. Induction of chronic pancreatitis with factors thought to have a role in human disease, such as combinations of lipopolysaccharide and chronic ethanol feeding, might be relevant to human disease. Models of autoimmune chronic pancreatitis have also been developed. Most models, particularly of chronic pancreatitis, require further characterization to determine which features of human disease they include.

The similarity of Type 1 autoimmune pancreatitis to pancreatic ductal adenocarcinoma with significant IgG4-positive plasma cell infiltration

BACKGROUND

High serum immunoglobulin G4 (IgG4) levels and infiltration of IgG4-positive cells are characteristic of Type 1 autoimmune pancreatitis (AIP). We previously reported that increased regulatory T cells (Tregs) may regulate IgG4 production in AIP. Although an increased serum IgG4 concentration is observed in some patients with pancreatic ductal adenocarcinoma (PDA), clarification is still necessary. We have therefore studied the correlations between IgG4-positive cells and Tregs in patients with PDA.

SUBJECTS AND METHODS

A total of 21 PDA and nine AIP patients were enrolled in our study. The numbers and ratios of Tregs, IgG4-positive, and IgG-positive cells immunohistochemically stained with anti-Foxp3, IgG4, and IgG antibodies, respectively, were counted in three areas of resected pancreata in PDA, peritumoral pancreatitis (PT), and obstructive pancreatitis (OP).

RESULTS

In PDA, PT, OP area, the number of IgG4-Positive cells (5.183 ± 1.061, 2.250 ± 0.431, 4.033 ± 1.018, respectively; p < 0.05) and the ratio of IgG4/IgG (0.391 ± 0.045, 0.259 ± 0.054, 0.210 ± 0.048, respectively; p < 0.05) were significantly lower than those in AIP (21.667 ± 2.436 and 0.306 ± 0.052, respectively). The numbers of IgG4-positive cells did not differ significantly among the three areas of resected pancreata examined. However, the IgG4/IgG (0.391 ± 0.045) and Foxp3/monocyte (0.051 ± 0.008) ratios in PDA area were significantly (p < 0.05) higher than those in OP area (IgG4/IgG: 0.210 ± 0.048; oxp3/monocyte: 0.0332 ± 0.005), but not in PT area. Of the 21 cases of PDA, the ratio of IgG4/IgG was >40 % in nine (43%), six (29%) and three (14%) cases in PDA, PT and OP area, respectively. Foxp3 and IgG4 were positively correlated in OP area, but not in PDA and PT area.

CONCLUSIONS

Clinicians should be careful when basing a differential diagnosis of PDA and AIP on the numbers of IgG4-positive cells and the ratio of IgG4/IgG, especially when determined using a small biopsied sample.

Long-term surgical outcomes of patients with type 1 autoimmune pancreatitis

BACKGROUND

Although pancreatectomy has sometimes been performed for patients with autoimmune pancreatitis (AIP) presenting atypical radiologic findings under the diagnosis of pancreatobiliary malignancy, the long-term surgical outcome of these patients had not yet been fully elucidated.

METHODS

The long-term surgical outcomes of 13 patients with pathologically diagnosed type 1 AIP with immunohistochemical staining for immunoglobulin G4 (IgG4) were retrospectively compared with those of 34 patients with conventional chronic pancreatitis to evaluate the residual pancreatic function.

RESULTS

A definite relapse of AIP in terms of the clinical manifestations and diagnostic imaging was not found in any of the patients, although one patient experienced an attack of acute pancreatitis caused by pancreatic stones, and stricture of the hepaticojejunostomy occurred in one patient. The overall body weight decreased significantly more in patients with AIP than in patients with conventional chronic pancreatitis (p < 0.05); however, there was no difference in the preoperative nondiabetic patients. Refractory diarrhea occurred in only one patient with AIP. The cumulative new-onset rates of diabetes mellitus of the ten patients with AIP and 24 patients with conventional chronic pancreatitis at 5 years after the surgery were 32.5 and 26.1 %, respectively (p = 0.70).

CONCLUSIONS

Careful long-term follow-up is needed for patients undergoing pancreatectomy for type 1 AIP because remnant pancreatic function can deteriorate as severely as that of patients who undergo pancreatectomy for conventional chronic pancreatitis. In the present series, however, there were few definite manifestations indicating relapse or the persistent existence of AIP.

Type 1 autoimmune pancreatitis can transform into chronic pancreatitis: a long-term follow-up study of 73 Japanese patients

Some patients with autoimmune pancreatitis (AIP) form pancreatic stones suggestive of transformation into chronic pancreatitis (CP). The present study examined the underlying risk factors and mechanism of AIP progression to confirmed CP. We compared the clinical and laboratory parameters of subjects who progressed to confirmed CP with those of the subjucts who did not in a cohort of 73 type 1 AIP patients. A total of 16 (22%) AIP patients progressed to CP. Univariate analysis revealed that relapse was significantly more frequent in the progression group, and multivariate analysis indicated that pancreatic head swelling (OR 12.7, P = 0.023) and nonnarrowing of the main pancreatic duct in the pancreatic body (OR 12.6, P = 0.001) were significant independent risk factors for progression to CP. Kaplan-Meier testing showed that the progression rate to CP was approximately 10% at 3 years and 30% at 10 years in total AIP patients and 30% at 3 years and 60% at 10 years in subjects with both risk factors. AIP with pancreatic head swelling and a history of relapse may cause pancreatic juice stagnation and nonnarrowing of the main pancreatic duct in the pancreatic body, which can progress to advanced stage chronic pancreatitis.

Asymptomatic and persistent elevation of pancreatic enzymes in an ulcerative colitis patient

Azathioprine has been extensively used in the management of inflammatory bowel diseases. It might cause pancreatic damage in the form of either asymptomatic elevation in serum amylase/lipase or overt acute pancreatitis. Here we report the case of a 61-year-old patient with ulcerative colitis who had been treated with azathioprine for three years, achieving clinical remission. During treatment he presented an asymptomatic elevation of serum pancreatic enzymes, without any signs of pancreatitis at imaging. This evidence brought us to reassess the drug dosage, without achieving a normalization of biochemical analysis. Autoimmune pancreatitis was excluded. One year after the suspension of azathioprine, we still face persistent high levels of amylase/lipase. Normalization of enzymatic values in patients who develop intolerance to azathioprine, in the form of either asymptomatic elevation in serum amylase/lipase or overt acute pancreatitis, is usually achieved in about two months after stopping drug intake. Asymptomatic elevation in serum pancreatic enzymes in the absence of pancreatic disease is reported in the literature and defined as “Gullo's syndrome,” but nobody of the subjects studied had been treated in the past with pancreatotoxic drugs. Might this case be defined as “benign pancreatic hyperenzymemia”?

A subset of Rosai-Dorfman disease exhibits features of IgG4-related disease

In this study we investigated the distribution of IgG4+ plasma cells and regulatory T (T(REG)) cells, a major regulator of IgG4 production, in nodal and extranodal Rosai-Dorfman disease (RDD). Twenty-six specimens (15 nodal, 11 extranodal) were examined, with reactive lymph nodes and site-matched extranodal specimens as controls. Overall, 84.6% (22/26) of the specimens showed various degrees of sclerosis (7 mild, 8 moderate, and 7 severe). Nineteen cases (73.1%) exhibited more than 10 IgG4+ cells/0.060 mm(2) (photographed area at ×40), and 8 cases (30.8%) showed more than 40% of IgG+ cells being IgG4+. Only 1 control case exhibited more than 10 IgG4+ cells/0.060 mm(2) (P < .05). The number of T(REG) cells was comparable between nodal RDD and controls, whereas extranodal RDD exhibited significantly higher numbers of T(REG) cells than controls. These findings demonstrate that a subset of RDD shows features of IgG4-related disease and indicate an overlap between certain aspects of the 2 diseases.

Intraductal papillary mucinous neoplasm of the pancreas and IgG4-related disease: a coincidental association

BACKGROUND/AIMS

Coexistence of autoimmune pancreatitis (AIP) and pancreatic cancer, elevation of serum IgG4 levels in pancreatic cancer patients, and infiltration of IgG4-positive plasma cells in peritumorous pancreatitis have been described in a few reports. This study examined the relationship between intraductal papillary mucinous neoplasm (IPMN) of the pancreas and peritumorous IgG4-positive lymphoplasmacytic infiltrates.

METHODS

Serum IgG4 levels were measured in 54 patients with IPMN (median 70 years, 26 males and 28 females; 13 main duct type and 41 branch duct type). Histological findings focusing on dense lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis were reviewed, and immunostaining with IgG4 and IgG was performed in 23 surgically resected IPMN cases (18 main duct type and 5 branch duct type). The presence of IgG4-positive plasma cells >10/hpf and an IgG4-positive/IgG-positive plasma cell ratio >40% were considered significant.

RESULTS

Serum IgG4 levels were elevated in 2 (4%) IPMN patients. Significant infiltration of IgG4-positive plasma cells was detected in 4 IPMN cases (17%). The IgG4-positive/IgG-positive plasma cell ratio was >40% in all 4 cases. In one case with a markedly elevated serum IgG4 level (624 mg/dL), typical lymphoplasmacytic sclerosing pancreatitis (AIP type 1) lesions surrounded the whole IPMN. In the 3 other cases, infiltration of IgG4-positive plasma cells with fibrosis was focally detected mainly in the periductal area around the IPMN.

CONCLUSIONS

In a few patients with IPMNs, IgG4-positive plasma cell infiltration can occur in the peritumorous area. The association of an IPMN with AIP type 1-like changes seems to be exceptional and coincidental.

High alcohol consumption increases the risk of pancreatic stone formation and pancreatic atrophy in autoimmune pancreatitis

OBJECTIVES

This study aimed to investigate risk factors for pancreatic stones and atrophy in autoimmune pancreatitis (AIP).

METHODS

Seventy-one patients with AIP observed for more than 1 year were enrolled. The frequency of pancreatic stone development and atrophy on computed tomography as well as their risk factors were examined.

RESULTS

Pancreatic stones and atrophy were observed in 13 and 43 patients, respectively. Alcohol consumption of greater than 50 g/d was the only significant risk factor for pancreatic atrophy in univariate analysis. Alcohol intake of greater than 50 g/d was observed in 6 of 13 patients with stones and 10 of 58 patients without stones (46% vs 17%, P = 0.059). Alcohol intake of greater than 50 g/d was observed in 14 of 43 patients with atrophy and 2 of 28 patients without atrophy (33% vs 7.1%, P = 0.018). In multivariate analysis, alcohol consumption was a significant risk factor both for pancreatic stone formation (odds ratio [OR], 7.47; P = 0.040) and atrophy (OR 6.24; P = 0.034). Higher age at onset was another significant risk factor for pancreatic atrophy (OR 1.07 per year; P = 0.029).

CONCLUSIONS

Alcohol consumption of greater than 50 g/d increases the risk of pancreatic stone development and atrophy in patients with AIP.

The role of peroral video cholangioscopy in patients with IgG4-related sclerosing cholangitis

BACKGROUND

The cholangioscopic features of IgG4-related sclerosing cholangitis (IgG4-SC) remain undefined. The aim of this study was to clarify these endoscopic features using peroral video cholangioscopy (PVCS) in IgG4-SC patients.

METHODS

PVCS was performed in 33 patients: IgG4-SC (n = 13); primary sclerosing cholangitis (PSC; n = 5); and cholangiocarcinoma (n = 15), which included hilar cholangiocarcinoma (HCCA; n = 5) and distal cholangiocarcinoma (DCCA; n = 10).

RESULTS

The most frequent findings on PVCS in the IgG4-SC patients were dilated (62 %) and tortuous (69 %) vessels, and absence of partially enlarged vessels. The incidence of dilated and tortuous vessels was significantly higher in IgG4-SC patients than in PSC patients (p = 0.015). Scarring and pseudodiverticula were found significantly more often in PSC patients than in IgG4-SC patients (p = 0.001 and p = 0.0007, respectively). The incidence of partially enlarged vessels was significantly higher in DCCA patients than in IgG4-SC patients (p = 0.004). In contrast, the incidence of dilated vessels was significantly higher in IgG4-SC patients than in HCCA patients (p = 0.015). PVCS performed after corticosteroid therapy showed resolution of bile duct stenosis and dilated, tortuous, or partially enlarged vessels, as well as resolution of friability in all patients with IgG4-SC.

CONCLUSION

Cholangioscopy was useful in differentiating IgG4-SC from PSC. In addition, monitoring the patterns of proliferative vessels on PVCS may be useful to differentiate IgG4-SC from cholangiocarcinoma.

Autoimmune pancreatitis: current concepts

Autoimmune pancreatitis (AIP) is a distinct type of chronic pancreatitis with unique clinical, pathological, serological, and imaging features. AIP usually presents with obstructive jaundice. Imaging studies often reveal enlargement of the pancreas with a pancreatic mass and strictures of the main pancreatic duct. Two subtypes of AIP have recently been identified. Type I AIP is more prevalent in elderly Asian males and is characterized by lymphoplasmacytic sclerosing pancreatitis, obliterative phlebitis, and infiltration of large numbers of IgG4-positive plasma cells. Type II AIP is more prevalent in Caucasians and is characterized by granulocyte epithelial lesions. Most patients with type I AIP have a significantly elevated serum IgG4 concentration, which is an important feature for diagnosis and for differentiating between AIP and other conditions such as pancreatic cancer. Extrapancreatic complications are common, such as sclerosing cholangitis, sclerosing sialadenitis, retroperitoneal fibrosis in type I AIP, and ulcerative colitis in type II AIP. A rapid response to glucocorticoids treatment is suggestive of AIP, but the relapse rate is high, warranting the use of immunosuppressant treatment. B-cell depletion with rituximab may be a promising therapy. The prognosis of AIP is generally benign if treated promptly, and spontaneous remission occurs in a proportion of patients.

A proposal of a diagnostic algorithm with validation of International Consensus Diagnostic Criteria for autoimmune pancreatitis in a Japanese cohort

BACKGROUND

Among many diagnostic criteria for autoimmune pancreatitis (AIP), the International Consensus Diagnostic Criteria (ICDC) first enabled us to diagnose and compare type 1 and type 2 AIP, which permitted tailoring individual diagnostic algorithms depending on local expertise. We compared them and validated ICDC with special reference to levels 1 and 2, and proposed a diagnostic algorithm for AIP in Japan.

METHODS

The diagnostic sensitivity of 5 major criteria (ICDC, Korean, Japanese-2011, Asian, and HISORt criteria) was compared, using 61 patients with AIP. Fifty six patients with pancreatic cancer served as a control. Pancreas imaging on computed tomography (CT) and endoscopic retrograde pancreatography (ERP) were independently evaluated by 3 pancreatologists (5, 10, and 20 years of career experience) and each diagnostic criterion of ICDC was validated with special reference to levels 1 and 2.

RESULTS

The sensitivities of 5 major criteria were 95.1% (ICDC), 90.2% (Korean), 86.9% (Japanese), 83.6% (Asian), and 83.6% (HISORt) with 100% of specificity in each. In the evaluation of pancreas imaging, diagnostic sensitivities of combination with CT and ERP in segmental/focal type AIP were significantly higher than single imaging (26% in CT (P < 0.01) or 35% in ERP (P < 0.05) vs 63% in CT + ERP), but not significantly different in the diffuse type.

CONCLUSIONS

Of the 5 criteria, ICDC is the most sensitive and useful for diagnosing AIP. We have proposed a diagnostic algorithm with CT for the diffuse type of AIP, and combination with CT + ERP followed by EUS-FNA for the segmental/focal type.

Current concept and diagnosis of IgG4-related disease in the hepato-bilio-pancreatic system

Recently, IgG4-related disease (IgG4-RD) has been recognized as a novel clinical entity with multiorgan involvement and unknown origin, associated with abundant infiltration of IgG4-positive cells. The Japanese research committee, supported by the Ministry of Health, Labor and Welfare of Japan, unified many synonyms for these conditions to the term "IgG4-RD" in 2009. The international symposium on IgG4-RD endorsed the comprehensive nomenclature as IgG4-RD, and proposed the individual nomenclatures for each organ system manifestations in 2011. Although the criteria for diagnosing IgG4-RD have not yet been established, proposals include the international pathological consensus (IPC) and the comprehensive diagnostic criteria (CDC) for IgG4-RD for general use, and several organ-specific criteria for organ-specialized physicians, e.g., the International consensus diagnostic criteria (ICDC) and the revised clinical diagnostic criteria in 2011 by the Japan Pancreas Society (JPS-2011) for type1 AIP; the Clinical Diagnostic Criteria 2012 for IgG4-sclerosing cholangitis (IgG4-SC-2012); the diagnostic criteria for IgG4-positive Mikulicz's disease by the Japanese Society for Sjogren's syndrome; and diagnostic criteria for IgG4-related kidney disease by the Japanese Society of Nephrology. In cases of probable or possible IgG4-RD diagnosed by the CDC, organ-specific diagnostic criteria should be concurrently used according to a diagnosis algorithm for IgG4-RD, with referral to a specialist.

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.

Differentiating immunoglobulin g4-related sclerosing cholangitis from hilar cholangiocarcinoma

Background/Aims

Few studies have differentiated immunoglobulin G (IgG) 4-related sclerosing cholangitis (IgG4-SC) from hilar cholangiocarcinoma (CC). Thus, we sought to investigate useful features for differentiating IgG4-SC from hilar CC.

Methods

We retrospectively compared clinical, serological, imaging, and histological features of six patients with IgG4-SC and 42 patients with hilar CC.

Results

In patients with hilar CC, obstructive jaundice was more frequent (p<0.01), serum total bilirubin levels were significantly higher (p<0.05), serum CA19-9 levels were significantly higher (p<0.01), and serum duke pancreatic monoclonal antigen type 2 levels were frequently elevated (p<0.05). However, in patients with IgG4-SC, the serum IgG (p<0.05) and IgG4 (p<0.01) levels were significantly higher and frequently elevated. The pancreas was enlarged in all IgG4-SC patients but only in 17% of hilar CC patients (p<0.01). Salivary and/or lacrimal gland swelling was detected in only 50% of IgG4-SC patients (p<0.01). Endoscopic retrograde cholangiography revealed that the hilar or hepatic duct was completely obstructed in 83% of hilar CC patients (p<0.01). Lower bile duct stenosis, apart from hilar bile duct stenosis, was more frequent in IgG4-SC patients (p<0.01). Bile duct wall thickening in areas without stenosis was more frequent in IgG4-SC patients (p<0.01).

Conclusions

An integrated diagnostic approach based on clinical, serological, imaging, and histological findings is necessary to differentiate IgG4-SC from hilar CC.

Reactive fibroinflammatory pseudotumor of the pancreas: report of three cases

Reactive fibroinflammatory pseudotumor located in the pancreas is a rare condition. However, we experienced three cases of reactive fibroinflammatory pseudotumor of the pancreas over the previous 2 years. Immunohistochemical staining of immunoglobulin G4 (IgG4) confirmed that Cases 1 and 3 involved IgG4-related disease and that Case 2 did not. In Cases 1 and 3, the masses were formed through autoimmune reaction and were diagnosed as autoimmune pancreatitis (AIP). In Case 2, because only a few IgG4-positive cells were found, it was difficult to diagnose AIP or IgG4-related disease. Reactive fibroinflammatory pseudotumors can develop without the involvement of any autoimmune mechanisms. There seems to be partial overlap between reactive fibroinflammatory pseudotumors and AIP.

Cholangiocarcinoma or IgG4-associated cholangitis: how feasible it is to avoid unnecessary surgical interventions?

OBJECTIVE

To evaluate the experience of a tertiary hepatopancreaticobiliary (HPB) center in the diagnostic approach and management of patients with suspicion of cholangiocarcinoma (CCa), focusing on excluding patients with IgG4-associated cholangitis (IAC) from unnecessary major surgical interventions.

METHODS

Between January 2008 and September 2010, a total number of 152 patients with suspicion of CCa underwent evaluation through a HPB multidisciplinary team meeting. Patients without tissue diagnosis were managed surgically or medically on the basis of probable presence of IAC as underlying pathology. Serology, immunostaining, and imaging were reviewed and analyzed according to the HISORt (Histology, Imaging, Serology, Other organ involvement, Response to therapy) criteria for IAC.

RESULTS

Tissue diagnosis during the diagnostic workup was achieved in 104 patients (68%), whereas the remaining 48 were classified as "highly suspicious for CCa" (n = 35) or as "probable IAC" (n = 13). Among 16 "highly suspicious for CCa" patients who underwent surgery, pathology revealed 2 patients harboring IAC (n = 1) and a benign chronic inflammatory biliary stricture (n = 1), respectively. Among the 13 patients with primarily medical management as "probable IAC," final diagnosis was CCa (n = 3) and IAC (n = 9), while 1 patient had no proven diagnosis. The accuracy of serum IgG4 for diagnosis of IAC reached 60%. Sensitivity and specificity of immunostaining for IAC in biopsy specimens were 56% and 89%, respectively. Imaging features suggesting IAC yielded sensitivity, specificity, and accuracy of 75%, 89%, and 83%, respectively. Initial imaging was revised at the referral institute in 75% of IAC patients (P = 0.009), while an isolated stricture (P = 0.038), a biliary mass (P = 0.006), and normal pancreas on computed tomography (P = 0.01) were statistically significant parameters for distinguishing between CCa and IAC. The mean time for establishing a diagnosis of IAC was 12.4 months (range: 2.5-32 months).

CONCLUSIONS

Differential diagnosis between CCa and IAC mandates high index of suspicion and low threshold for referral in high volume institutes. The delayed establishment of diagnosis particularly for CCa needs to be balanced versus avoiding unnecessary surgery for IAC. Imaging features may be most helpful for optimal management.

[Pancreatic cancer or autoimmune pancreatitis: endosonography as a diagnostic reviser]

Conventional radiologic imaging (abdominal ultrasound, computer tomography) used in the differential diagnosis of post-hepatic jaundice can frequently provide inaccurate diagnosis. Inflammatory lesions may mimic neoplastic processes and malignancy may be accompanied by perifocal inflammation resulting in histological misdiagnosis. Furthermore, chronic and autoimmune pancreatitis are associated with an increased risk for pancreatic cancer. Radial endosonography has become a markedly important method in the imaging of the pancreas. It has a crucial role in the diagnosis and staging of pancreatic cancer. The authors present three cases where the diagnosis of pancreatic cancer determined by conventional imaging techniques (abdominal ultrasound, computer tomography, endoscopic retrograde cholangiopancreatography) was excluded or confirmed by the radial endosonography. The authors conclude that radial endosonography is an essential complementary method among imaging techniques of the pancreas and in tumor staging. Application of that may prevent unnecessary surgeries, which is obviously useful for patients and cost effective for health care providers.

Autoimmune pancreatitis mimicking pancreatic tumor

Autoimmune pancreatitis (AIP) is a rare disease of unknown pathomechanism. It belongs to the IgG4-related disease family and responds well to steroids, although the relapse rate can reach up to 20–30%. Differentiating AIP from the more common pancreatic cancer can be very challenging. About 20% of AIP is diagnosed postoperatively during final histological examination. Each of the investigative tools can add something to the definitive diagnosis; the question remains whether it is possible to prevent an unnecessary resection. Through our case we would like to demonstrate the differential diagnostic opportunities and present the literary background of this issue. In conclusion, we can state that whenever a focal pancreatic lesion is encountered AIP should always be considered.

The pathology of IgG4-related disease: critical issues and challenges

IgG4-related disease (IgG4-RD) is a chronic and relapsing disease. The diagnosis of IgG4-RD is based on a combination of features that include clinical, imaging, serologic, histology, and immunohistochemistry. Nonetheless, histopathology has emerged as the gold standard for the diagnosis of IgG4-RD. Guidelines for the pathologic diagnosis of this condition have been published by an international group of experts: a triumvirate of histologic features allows for a confident diagnosis of IgG4-RD to be made in most cases: (1) a dense lymphoplasmacytic infiltrate, (2) storiform-type fibrosis, and (3) obliterative phlebitis. Elevated numbers of IgG4-positive plasma cells are essential for the diagnosis, but this feature is not sufficient in, and of, itself. IgG4-positive plasma cells are also seen in a variety of inflammatory and neoplastic diseases. An elevated IgG4 to IgG ratio, more than 40%, improves the specificity of this stain. A wide range of inflammatory and neoplastic diseases including antineutrophil cytoplasmic antibody (ANCA)-related vasculitis, chronic infections, mesenchymal neoplasms, carcinoma, and lymphoma should be excluded before arriving at a diagnosis of IgG4-RD. This review aims to provide the histopathologist with a set of practical guidelines for the diagnosis of IgG4-RD, and also addresses the many controversies associated with the diagnostic aspects of this disease.

Autoimmune pancreatitis: a guide for the histopathologist

Autoimmune pancreatitis (AIP) is a distinct form of pancreatitis with a characteristic histological appearance. Clinically and radiologically, many of these patients show enlargement of pancreas and pancreatic duct/bile duct strictures, thus mimicking pancreatic carcinoma. There are 2 forms of the disease: (1) type 1 AIP characterized by storiform type fibrosis, obliterative phlebitis, and elevated numbers of immunoglobulin G4 (IgG4) positive plasma cells, typically >50 per high-power field, and, (2) type 2 AIP characterized by granulocytic epithelial lesions and only occasional IgG4-bearing plasma cells, typically <10 per high-power field. The type 1 variant of AIP is the pancreatic manifestation of IgG4-related disease, thus both pancreatic and extrapancreatic recurrences are common. The type 2 variant is unrelated to IgG4-related disease, and disease recurrence is uncommon. Both forms of the disease show a swift response to immunosuppressive therapy. This review highlights the clinical and pathological differences between the 2 forms of AIP. We also review guidelines that assist in distinguishing AIP from its closest mimic, pancreatic adenocarcinoma.

Immunoglobulin G4-related sclerosing cholangitis: pathologic features and histologic mimics

Since immunoglobulin G4 (IgG4)-related sclerosing cholangitis was first described in 2004, this condition has been recognized as a distinct entity characterized by unique pathologic features. Affected bile ducts show diffuse wall thickening, which represents transmural sclerosing inflammation composed of a dense lymphoplasmacytic infiltrate and fibrosis arranged at least focally in a storiform pattern. A diffuse IgG4-positive plasma cell infiltrate is demonstrable by immunohistochemistry. More than 90% of patients with IgG4-related sclerosing cholangitis have type 1 autoimmune pancreatitis, the remaining presenting as isolated cholangitis. The diagnosis requires a multidisciplinary approach, in which pathologic examination has a critical role. Tissue diagnosis on biopsy specimens (ie, bile duct biopsy, liver needle biopsies) is important, particularly for patients with isolated cholangitis, given the fact that radiological findings of IgG4-cholangitis are not reliable enough for establishing the diagnosis. Furthermore, serum IgG4 levels can be, albeit mildly, elevated in other biliary disorders. Histologic mimics of IgG4-related sclerosing cholangitis include primary sclerosing cholangitis, follicular cholangitis, and sclerosing cholangitis with granulocytic epithelial lesion, the latter 2 being recently described entities.

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.

The Spanish Pancreatic Club recommendations for the diagnosis and treatment of chronic pancreatitis: part 1 (diagnosis)

Chronic pancreatitis (CP) is a relatively uncommon, complex and heterogeneous disease. The absence of a gold standard applicable to the initial phases of CP makes its early diagnosis difficult. Some of its complications, particularly chronic pain, can be difficult to manage. There is much variability in the diagnosis and treatment of CP and its complications amongst centers and professionals. The Spanish Pancreatic Club has developed a consensus on the management of CP. Two coordinators chose a multidisciplinary panel of 24 experts on this disease. A list of questions was drafted, and two experts reviewed each question. Then, a draft was produced and shared with the entire panel of experts and discussed in a face-to-face meeting. This first part of the consensus addresses the diagnosis of CP and its complications.

Thrombotic thrombocytopenic purpura (TTP) leading to pseudotumour's autoimmune pancreatitis (AIP): a case report

INTRODUCTION

Autoimmune pancreatitis is an idiopathic inflammatory disease that produces pancreatic masses and ductal strictures. This benign disease can be associated with extrapancreatic manifestations including cholangitis, sialadenitis, inflammatory bowel disease or retroperitoneal fibrosis, mediastinal adenopathy, interstitial nephritis mainly due to immunoglobulin G4 (Ig G4), and occasional association with other auto-immune diseases.

OBSERVATION

We report a 57-year-old woman who developed thrombotic thrombocytopenic purpura (TTP) and pseudo-tumour's seronegative autoimmune pancreatitis (AIP) type 1. The patient was initially treated with pulse corticosteroids and plasmapheresis; afterwards two cures of i.v. Vincristin with inadequate response and subsequently with four weekly pulses dose of i.v. Rituximab, leading to full remission.

CONCLUSION

This case represents the first report of TTP associated to pseudo-tumour's seronegative AIP type 1 successfully treat by Rituximab.

Newly developed autoimmune cholangitis without relapse of autoimmune pancreatitis after discontinuing prednisolone

A 57-year-old man presented with a 2-wk history of painless jaundice and weight loss. He had a large ill-defined enhancing mass-like lesion in the uncinate process of the pancreas with stricture of the distal common bile duct. Aspiration cytology of the pancreatic mass demonstrated inflammatory cells without evidence of malignancy. Total serum immunoglobulin G level was slightly elevated, but IgG4 level was normal. After the 2-wk 40 mg prednisolone trial, the patient’s symptoms and bilirubin level improved significantly. A follow-up computed tomography (CT) scan showed a dramatic resolution of the pancreatic lesion. A low dose steroid was continued. After six months he self-discontinued prednisolone for 3 wk, and was presented with jaundice again. A CT scan showed newly developed intrahepatic biliary dilatation and marked concentric wall thickening of the common hepatic duct and the proximal common bile duct without pancreatic aggravation. The patient’s IgG4 level was elevated to 2.51 g/L. Prednisolone was started again, after which his serum bilirubin level became normal and the thickening of the bile duct was resolved. This case suggests that autoimmune pancreatitis can progress to other organs that are not involved at the initial diagnosis, even with sustained pancreatic remission.

Comparative study on experimental autoimmune pancreatitis and its extrapancreatic involvement in mice

OBJECTIVE

The objective of the study was to study the relationship between autoimmune pancreatitis (AIP) and colitis in C57BL/6 interleukin 10-deficient (IL-10KO) mice and to compare the extrapancreatic involvement of AIP between IL-10KO and MRL/Mp mice that developed pancreatitis.

METHODS

Six-week-old female IL-10KO and MRL/Mp mice were injected intraperitoneally with polyinosinic polycytidylic acid (poly I:C) twice weekly for 8 or 12 weeks, respectively. The mice were killed, and the severity of inflammation in the pancreas, colon, liver, bile duct, and salivary gland was assessed using histological scoring systems. T-cell subsets derived from IL-10KO mice with pancreatitis were adoptively transferred into recombination activating gene 2-deficient mice.

RESULTS

Administration of poly I:C induced pancreatitis and accelerated the development of colitis in IL-10KO mice. Pancreatitis was characterized by specific destruction of exocrine glands and the production of various autoantibodies. Involvement of the liver and bile duct was observed in both IL-10KO and MRL/Mp mice, but sialadenitis was present only in MRL/Mp mice. Adoptive transfer of CD4(+) T cells from AIP mice induced pancreatitis in recipient mice.

CONCLUSIONS

Pancreatitis in IL-10KO mice resembles human type 1 AIP and is not associated with colitis. Genetic background may affect susceptibility to extrapancreatic involvement in type 1 AIP.

Pseudotumoral autoimmune pancreatitis mimicking a pancreatic cancer: a very difficult disease to diagnose

Autoimmune pancreatitis (AIP) is a rare disorder, although the exact prevalence is still unkown. It is a type of pancreatitis that is presumed to have an autoimmune aetiology, and is currently diagnosed based on a combination of 5 criteria. However, in this day and age, some patients with AIP are likely to be resected for the suspicion of malignancy. The authors report a case of pseudo-tumoral autoimmune pancreatitis, reviewing some literature about it and underlining the difficulty in the diagnosis. A 56-year-old patient was referred to our unit for upper abdominal pain. In his past medical history we note mellitus diabetes. The clinical examination was unremarkable. Laboratory data showed no abnormal values. Upper endoscopy showed antral gastritis. Transabdominal ultrasonography showed a hepatic steatosis and 5 angiomas. No computed tomography scan was made. Magnetic resonance imaging (MRI) showed 5 angiomas and a lesion of 20×20 mm of the pancreatic tail with decreased signal intensity on T1-weighted MR images, increased signal intensity on T2-weighted MR images. Due to concerns of pancreatic malignancy, the patient underwent open distal spleno-pancreatectomy. Histolo gical analysis of the resected specimen revealed no malignancy. Postoperatively, immunoglobulin G fraction 4 was slightly above of the upper limit of the normal range. After corticotherapy the patient is getting better. This case underlines the difficulties still encountered in the diagnosis of AIP. It has been frequently misdiagnosed as pancreatic cancer and caused unnecessary resection. In order to avoid unnecessary resections for an otherwise benign and easily treatable condition, it is urgent to refine diagnostic criteria and to reach an international consensus.

IgG4 Inflammatory Pseudotumor of the Kidney

Hyper-IgG4 disease is a rare systemic disorder that usually affects middle age males. It is characterized by elevated serum IgG4 levels and infiltration of organs by IgG4 positive plasma cells associated with fibrosis. Patients usually present with mass or masses in the involved organ that mimic neoplasia. While initially described in the pancreas, IgG4-related inflammatory tumors have been now described in many organs. We describe an unusual case of an IgG4-related pseudotumor of the kidney.

Recent advances in autoimmune pancreatitis

It is now clear that are two histological types (Type-1 and Type-2) of autoimmune pancreatitis (AIP). The histological pattern of Type-1 AIP, or traditional AIP, is called lymphoplasmacytic sclerosing pancreatitis (LPSP). The histological pattern of Type-2 AIP is characterized by neutrophilic infiltration in the epithelium of the pancreatic duct. In general, Type-2 AIP patients are younger, may not have a male preponderance, and rarely show elevation of serum IgG4 compared with Type-1 AIP patients. Unlike Type-1 AIP patients, Type-2 AIP patients rarely have associated sclerosing diseases, but they are more likely to have acute pancreatitis and ulcerative colitis. Although Type-2 AIP is sometimes observed in the USA and Europe, most AIP cases in Japan and Korea are Type-1. The international consensus diagnostic criteria for AIP comprise 5 cardinal features, and combinations of one or more of these features provide the basis for diagnoses of both Type-1 and Type-2 AIP. Due to the fact that steroid therapy is clinically, morphologically, and serologically effective in AIP patients, it is the standard therapy for AIP. The indications for steroid therapy in AIP include symptoms such as obstructive jaundice and the presence of symptomatic extrapancreatic lesions. Oral prednisolone (0.6 mg/kg/day) is administered for 2-4 weeks and gradually tapered to a maintenance dose of 2.5-5 mg/day over a period of 2-3 months. Maintenance therapy by low-dose prednisolone is usually performed for 1-3 years to prevent relapse of AIP.

Serum proteome profiling of pancreatitis using recombinant antibody microarrays reveals disease-associated biomarker signatures

PURPOSE

Pancreatitis is an inflammatory state of the pancreas, for which high-performing serological biomarkers are lacking. The aim of the present study was to evaluate the use of affinity proteomics for identifying potential markers of disease and stratifying pancreatitis subtypes.

EXPERIMENTAL DESIGN

High-content, recombinant antibody microarrays were applied for serum protein expression profiling of 113 serum samples from patients with chronic, acute, and autoimmune pancreatitis, as well as healthy controls. The sample groups were compared using supervised classification based on support vector machine analysis.

RESULTS

This discovery study showed that pancreatitis subtypes could be discriminated with high accuracy. Using unfiltered data, the individual subtypes, as well as the combined pancreatitis cohort, were distinguished from healthy controls with high AUC values (0.96-1.00). Moreover, characteristic protein patterns and AUC values in the range of 0.69-0.95 were observed for the individual pancreatitis entities when compared to each other, and to all other samples combined.

CONCLUSIONS AND CLINICAL RELEVANCE

This study demonstrated the potential of the antibody microarray approach for stratification of pancreatitis. Distinct candidate multiplex serum biomarker signatures for chronic, acute, and autoimmune pancreatitis were defined, which could enhance our fundamental knowledge of the underlying molecular mechanisms, and potentially lead to improved diagnosis.

Recent advances in research of immunoglobulin G4-related sclerosing cholangitis

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is a recently defined disease entity characterized by elevated serum IgG4, chronic progressive obstructive jaundice, and diffuse or mass-forming inflammatory reaction rich in IgG4-positive plasma cells and lymphocytes associated with fibrosclerosis and obliterative phlebitis, which shares a number of clinical, biochemical, and radiological features with primary sclerosing cholangitis (PSC) or cholangiocarcinoma (CC). IgG4-SC is commonly associated with autoimmune pancreatitis (AIP). Steroid therapy comprises the mainstay of treatment for IgG4-SC patients. However, liver transplantation is the only useful treatment for PSC patients, and CC patients require surgical therapy. Therefore, the accurate discrimination between IgG4-SC and PSC or CC is a very important issue. In this article, we will review the features and role of immunoglobulin G4 (IgG4), the diagnosis and therapy of IgG4-SC, and the relations between IgG4-SC and AIP, PSC or CC.

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.