Diagnosis of autoimmune pancreatitis: the Mayo Clinic experience.

BACKGROUND & AIMS: The Japan Pancreas Society criteria for diagnosis of autoimmune pancreatitis (AIP) mandate presence of characteristic imaging (diffuse pancreatic enlargement with diffusely irregular, narrow pancreatic duct). AIP has unique histologic features associated with infiltration of tissues of affected organs with abundant IgG4-positive cells. We propose expanded diagnostic criteria for AIP with a cohort of histologically confirmed AIP. METHODS: We reviewed the pancreatic imaging findings on computed tomography scans, serum IgG4 levels, other organ involvement, and response to steroids in 29 consecutive patients who met histologic criteria for AIP. RESULTS: Computed tomography scans (n = 22) showed diffuse pancreatic enlargement in 6 (27%) patients; the rest had focal enlargement, distinct mass, normal pancreas, or focal acute pancreatitis. Serum IgG4 level was elevated in 15 of 21 (71%) patients, and other organ involvement (eg, intrahepatic biliary strictures) was noted in 11 of 29 (38%) patients. All 17 patients treated with steroids exhibited resolution/marked improvement of pancreatic/extrapancreatic manifestation. On the basis of this experience we propose that diagnosis of AIP can be made in patients with > or =1 of these criteria: (1) diagnostic histology, (2) characteristic imaging on computed tomography and pancreatography with elevated serum IgG4 level, or (3) response to steroid therapy of pancreatic/extrapancreatic manifestations of AIP. Twenty additional patients met expanded diagnostic criteria for AIP, and their demographic and clinical profile was similar to that of the 29 patients meeting histologic criteria. CONCLUSIONS: AIP defined by histological criteria shows a wide spectrum of radiologic features, with characteristic imaging seen only in a minority. Incorporation of additional features into current diagnostic criteria can identify the full spectrum of clinical presentations of AIP.     

Value of serum IgG4 in the diagnosis of autoimmune pancreatitis and in distinguishing it from pancreatic cancer

OBJECTIVES: To determine the sensitivity and specificity of elevated serum IgG4 level for the diagnosis of autoimmune pancreatitis (AIP) and its ability to distinguish AIP from pancreatic cancer, its main differential diagnosis. METHODS: We measured serum IgG4 levels (normal 8-140 mg/dL) in 510 patients including 45 with AIP, 135 with pancreatic cancer, 62 with no pancreatic disease, and 268 with other pancreatic diseases. RESULTS: Sensitivity, specificity, and positive predictive values for elevated serum IgG4 (>140 mg/dL) for diagnosis of AIP were 76%, 93%, and 36%, respectively, and 53%, 99%, and 75%, respectively, for IgG4 of >280 mg/dL. Among subjects with elevated IgG4, non-AIP subjects (N = 32) differed from AIP subjects (N = 34) in that they were more likely to be female (45%vs 9%, P < 0.001), less likely to have serum IgG4 >280 mg/dL (13%vs 71%, P < 0.001), or elevation of total IgG (16%vs 56%, P < 0.001). Serum IgG4 levels were elevated in 13/135 (10%) pancreatic cancer patients; however, only 1% had IgG4 levels >280 mg/dL compared with 53% of AIP. Compared with AIP, pancreatic cancer patients were more likely to have CA19-9 levels of >100 U/mL (71%vs 9%, P < 0.001). CONCLUSION: Elevated serum IgG4 levels are characteristic of AIP. However, mild (<2-fold) elevations in serum IgG4 are seen in up to 10% of subjects without AIP including pancreatic cancer and cannot be used alone to distinguish AIP from pancreatic cancer. Because AIP is uncommon, IgG4 elevations in patients with low pretest probability of having AIP are likely to represent false positives.     

Increase diagnostic accuracy in differentiating focal type autoimmune pancreatitis from pancreatic cancer with combined serum IgG4 and CA19-9 levels

Background/objectivesTo distinguish autoimmune pancreatitis (AIP), especially focal type, from pancreatic cancer, is a greatest challenge for clinician. The aim of the study is to compare the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of combined serum IgG4 and CA19-9 levels to differentiate AIP from pancreatic cancer by HISORt, Asian and international consensus diagnostic criteria.MethodsWe measured serum IgG4, CEA, and CA19-9 levels in 188 AIP patients, 86 non-AIP chronic pancreatitis patients, and 130 pancreatic cancer patients. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were compared with different diagnostic criteria. We also compared the diagnostic performance in patients with or without jaundice.ResultsThe serum level of IgG4 was significantly higher in AIP than those in non-AIP chronic pancreatitis and pancreatic cancer. The optimal cutoffs of IgG4 and CA19-9 to differentiate AIP from pancreatic cancer were 175 mg/dL and 85.0 U/ml based on ROC analysis. Combining IgG4 level over 280 mg/dL and CA19-9 below 85.0 U/ml could yield a best diagnostic accuracy (85.6%) to distinguishing AIP from pancreatic cancer in all of the HISORt, Asian and international consensus diagnostic criteria. With the combination of serological test, focal type AIP could be diagnosed with comparable accuracy as diffuse type AIP.ConclusionsOur study demonstrated that combined use of serum IgG4 (over 280 mg/dL) and CA19-9 9 (below 85.0 U/ml) together increases the diagnostic accuracy to distinguish AIP from pancreatic cancer non-invasively, especially in focal type autoimmune pancreatitis.     

Autoimmunpankreatitis

Autoimmune pancreatitis (AIP) has been established for more than 15?years as a disease entity of chronic pancreatitis. Although the autoimmune etiology is well established AIP is still an enigmatic disease. Morphological hallmarks of the disease are narrowing of the pancreatic duct system and frequently even narrowing of the bile duct by periductal lymphoplasmocytic inflammation. In cases of more localized inflammation obstructive jaundice due to a mass-forming lesion in the pancreatic head may mimic pancreatic ductal adenocarcinoma. Therefore, even in tertiary referral center, AIP patients underwent pancreatic surgery for suspected pancreatic cancer due to misclassification. Histopathologically, the disease can be differentiated into lymphoplasmacytic sclerosing pancreatitis (LPSP) with IgG4-positive cells or idiopathic ductocentral chronic pancreatitis (IDCP) with granulocyte epithelial lesions and eosinophils. Recently, LPSP has been coined AIP type 1 and IDCP as AIP type 2 following a recent consensus conference. Serologically, patients may present with elevated serum IgG and IgG4 levels. Additionally, autoantibodies have been described targeting ductal and acinar antigens. Association with other autoimmune manifestations in a wide range of organs is relatively frequent. In most cases, autoimmune pancreatitis responds to steroid treatment very quickly, which is of specific importance when considering the differential diagnosis of pancreatic cancer.     

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.     

Autoimmune pancreatitis: Multimodality non-invasive imaging diagnosis

Autoimmune pancreatitis(AIP)is characterized by obstructive jaundice,a dramatic clinical response to steroids and pathologically by a lymphoplasmacytic infiltrate,with or without a pancreatic mass.Type 1AIP is the pancreatic manifestation of an Ig G4-related systemic disease and is characterized by elevated Ig G4serum levels,infiltration of Ig G4-positive plasma cells and extrapancreatic lesions.Type 2 AIP usually has none or very few Ig G4-positive plasma cells,no serum Ig G4 elevation and appears to be a pancreas-specific disorder without extrapancreatic involvement.AIP is diagnosed in approximately 2%-6%of patients that undergo pancreatic resection for suspected pancreatic cancer.There are three patterns of autoimmune pancreatitis:diffuse disease is the most common type,with a diffuse,“sausage-like”pancreatic enlargement with sharp margins and loss of the lobular contours;focal disease is less common and manifests as a focal mass,often within the pancreatic head,mimicking a pancreatic malignancy.Multifocal involvement can also occur.In this paper we describe the features of AIP at ultrasonography,computed tomography,magnetic resonanceand positron emission tomography/computed tomography imaging,focusing on diagnosis and differential diagnosis with pancreatic ductal adenocarcinoma.It is of utmost importance to make an early correct differential diagnosis between these two diseases in order to identify the optimal therapeutic strategy and to avoid unnecessary laparotomy or pancreatic resection in AIP patients.Non-invasive imaging plays also an important role in therapy monitoring,in follow-up and in early identification of disease recurrence.     

Diagnostic criteria for autoimmune pancreatitis in Japan

Autoimmune pancreatitis （AIP） is a particular type of pancreatitis of presumed autoimmune etiology. Currently, AIP should be diagnosed based on combination of clinical, serological, morphological, and histopathological features. When diagnosing AIP, it is most important to differentiate it from pancreatic cancer. Diagnostic criteria for AIP, proposed by the Japan Pancreas Society in 2002 first in the world, were revised in 2006. The criteria are based on the minimum consensus of AIP and aim to avoid misdiagnosing pancreatic cancer as far as possible, but not for screening AIR The criteria consist of the following radiological, serological, and histopathological items： （1） radiological imaging showing narrowing of the main pancreatic duct and enlargement of the pancreas, which are characteristic of the disease; （2） laboratory data showing abnormally elevated levels of serum y-globulin, IgG or IgG4, or the presence of autoantibodies; （3） histopathological examination of the pancreas demonstrating marked fibrosis and prominent infiltration of lymphocytes and plasma cells, which is called lymphoplasmacytic sclerosing pancreatitis （LPSP）. For a diagnosis of AIP, criterion 1 must be present, together with criterion 2 and/ or criterion 3. However, it is necessary to exclude malignant diseases such as pancreatic or biliary cancer.     

Autoimmune pancreatitis: current diagnostic criteria are suboptimal

Background and Aims: The preoperative diagnosis of autoimmune pancreatitis (AIP) is difficult, given its similar clinical presentation to pancreatic cancer. The aims of the study are to describe our center's experience with AIP and apply the Japanese AIP diagnostic criteria to a cohort of patients with histologically‐proven AIP in order to assess their performance characteristics. Methods: A prospective pathology database was queried for AIP patients who were evaluated and/or treated at Johns Hopkins Hospital from 2002 to 2009. AIP histology was defined by the presence of lymphoplasmacytic infiltration, periductal inflammation, fibrosis, and periphlebitis. Imaging, clinical, and biochemical data were analyzed. Results: Thirty patients had pancreatic resection with pathological confirmation of AIP. Imaging revealed pancreatic mass (45%), focal prominence without mass lesion (24%), diffuse enlargement (17%), and normal pancreas (14%). Twenty‐four patients underwent an endoscopic retrograde cholangiopancreatography and/or magnetic resonance cholangiopancreatography, and 4/24 (17%) had pancreatic ductal narrowing or irregularity. Extrapancreaticobiliary organ involvement was found in 6% (n = 2) of patients. Biliary strictures were present in 87% of patients. Of 16 patients who underwent preoperative tissue biopsy, 10 had non‐diagnostic pathology, five had cellular atypia, and one had AIP. Serum immunoglobulin G4 (IgG4) levels were elevated in 12 of 29 (41%) patients. Three (10%) patients had evidence of extrapancreatic manifestations of AIP. When applying the Japanese criteria to the 27 patients who had serum IgG4 measurement, preoperative biopsy, and cross‐sectional abdominal imaging, only 44% of the patients would have been diagnosed accurately. Conclusions: When applied to a highly‐selected single‐center referral population in the USA, current Japanese guidelines for the diagnosis of AIP are found to have suboptimal sensitivity.     

I型自身免疫性胰腺炎的研究进展

自身免疫性胰腺炎（AIP）是逐渐被认识的慢性胰腺炎的一种类型,与其他类型的慢性胰腺炎有明显的不同。随着2001年发现AIP患者血清IgG4含量明显增高,这个现实被广泛的接受。1型AIP与2型AIP不同。2％的慢性胰腺炎为1一AIP,成人男性患者居多。患者通常由于胰头的增大或胆管壁增厚所致梗阻性黄疸,通过血清学、影像学和组织学与胰腺癌鉴别。血清IgG4水平的增高是最为敏感和特异性的表现。影像学的表现为胰管的不规则狭窄,胰腺弥散性或局灶性的扩大及胰周可见环形的囊壳样影,以及影像延迟期强化。组织学显示大量的dxDt问质表现为致密的纤维化伴席纹状、炎细胞浸润,闭塞性静脉炎和lgG4阳性细胞数量增加。激素治疗疗效明显是另外的特征,在初治的2～3周血清学和影像学明显改善。基于同步或不同步的伴有多器官的损伤,1一AIP也被认为是一种IgG4相关全身性疾病。至今有一些与1一AIP相关的自身免疫性抗原被鉴定,但IgG4在此病中的作用是肯定的。     

Autoimmunpankreatitis – „the new kid on the block“

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis which is characterized by diffuse or focal pancreatic enlargement, a lymphoplasmacytic infiltrate with a storiform fibrosis and a dramatic response to steroid treatment. AIP can be classified into three subtypes: lymphoplasmacytic sclerosing pancreatitis (LPSP; AIP type 1), idiopathic duct centric pancreatitis (IDCP; AIP type 2), and not otherwise specified (NOS). AIP type 1 is the pancreatic manifestation of IgG4-related disease which also involves other organs; AIP type 2 is a pancreas-specific, IgG4-negative disorder and is associated with inflammatory bowel disease. Epidemiological studies from Japan estimate an incidence of approximately 0.82 per 100,000 inhabitants; in Europe 5–6% of all patients with chronic pancreatitis are diagnosed with AIP. The pathomechanism of AIP remains enigmatic, but a mulitfactorial etiology with genetic predisposition and environmental influences has been proposed. Clinically, patients can present with jaundice, epigastric pain, weight loss and new-onset diabetes, thus, raising suspicion for pancreatic malignancy. A combination of the HISORt (Histology, Imaging, IgG4 Serology, other Organ involvement and Response to steroid therapy) criteria can be used to definitively diagnose AIP in most cases. The greatest challenge is to differentiate AIP from pancreatic cancer and cholangiocarcinoma, since it often presents with a pancreatic mass, lymphadenopathy and bile duct obstruction. The prognosis of AIP is usually favorable; in over 90% of cases remission can be induced by steroid treatment.     

Diagnosis and management of autoimmune pancreatitis： Experience from China

AIM： To determine the clinical, radiographic and pathologic characteristics, diagnostic and treatment modalities in patients with autoimmune pancreatitis （AIP）. METHODS： In this retrospective study, the data of patients with diagnosed chronic pancreatitis （CP） between 1995 and 2006 in Chinese PLA General Hospital were included to screen for the cases with AIP, according to the following diagnostic criteria： （1） diagnostic histopathologic features, and abound IgG4-positive plasma cells on pancreatic tissues; （2） characteristic imaging on computed tomography and pancreatography, together with increased serum IgG, y-globulin levels or presence of autoantibodies; （3） response to steroid therapy. The clinical, radiographic and pathologic characteristics, diagnostic and treatment modalities, and outcome of AIP cases were reviewed. RESULTS： Twenty-five （22 male, 3 female; mean age 54 years, 36-76 years） out of 510 CP patients were diagnosed as AIP, which accounted for 49% （21/43） of CP population undergoing surgical treatment in the same period. The main clinical manifestations included intermittent or progressive jaundice in 18 cases （72%）, abdominal pain in 11 （44%）, weight loss in 10 （40%）, and 3 cases had no symptoms. The imaging features consisted of pancreatic enlargement, especially in the head of pancreas （18 cases）, strictures of main pancreatic duct and intrapancreatic bile duct. Massive lymphocytes and plasma cells infiltration in pancreatic tissues were showed on pathology, as well as parenchymal fibrosis. Twenty-three patients were misdiagnosed as pancreaticobiliary malignancy, and 21 patients underwent exploratory laparotomy, theremaining 4 patients dramatically responded to steroid therapy. No pancreatic cancer occurred during a mean 46-mo follow-up period. CONCLUSION： AIP patients always are subjected to mistaken diagnosis of pancreatic cancer and an unnecessary surgical exploration, due to its similarity in clinical features with pancreatic cancer. T     

Incidence of the focal type of autoimmune pancreatitis in chronic pancreatitis suspected to be pancreatic carcinoma: experience of a single tertiary cancer center

Objective. With an increase in autoimmune pancreatitis (AIP) being reported, the focal type of AIP, which shows localized narrowing of the main pancreatic duct and focal swelling of the pancreas, has recently been recognized. Therefore, cases of focal-type AIP subjected to surgical intervention for presumptive malignancy might previously have been diagnosed as mass-forming chronic pancreatitis. The aim of this study was to elucidate the incidence of focal-type AIP in resected chronic pancreatitis at a single tertiary cancer center. The clinical and radiological features of focal-type AIP were also evaluated. Material and methods. We re-evaluated 15 patients who underwent pancreatic resection with a presumed diagnosis of pancreatic ductal adenocarcinoma, and who in the past had been diagnosed pathologically as having chronic pancreatitis. Results. Seven of 15 patients showed AIP, and the other 8 patients were diagnosed as having mass-forming chronic pancreatitis not otherwise specified by pathological retrospective examination. In other words, nearly half of the cases of resected chronic pancreatitis that were suspected to be pancreatic carcinoma preoperatively showed focal-type AIP. Regarding the characteristic findings of focal-type AIP, narrowing of the pancreatic duct on endoscopic retrograde pancreatography (ERP) might be diagnostic. Conclusions. Focal-type AIP is not a rare clinical entity and might be buried in previously resected pancreatic specimens that in the past were diagnosed simply as mass-forming pancreatitis.     

IgG4-unrelated type 1 autoimmune pancreatitis

A 50-year-old male was referred to our hospital for the evaluation of hyperproteinemia.Fluorodeoxyglucose positron emission tomography revealed high fluorodeoxyglucose uptake in the pancreas,bilateral lacrimal glands,submandibular glands,parotid glands,bilateral pulmonary hilar lymph nodes,and kidneys.Laboratory data showed an elevation of hepatobiliary enzymes,renal dysfunction,and remarkably high immunoglobulin(Ig) G levels,without elevated serum IgG4.Abdominal computed tomography revealed swelling of the pancreatic head and bilateral kidneys.Endoscopic retrograde cholangiopancreatography showed an irregular narrowing of the main pancreatic duct in the pancreatic head and stricture of the lower common bile duct.Histological examination by endoscopic ultrasonography-guided fine-needle aspiration revealed findings of lymphoplasmacytic sclerosing pancreatitis without IgG4-positive plasma cells.Abnormal laboratory values and the swelling of several organs were improved by the treatment with steroids.The patient was diagnosed as having type 1 autoimmune pancreatitis(AIP) based on the International Consensus Diagnostic Criteria.Therefore,we encountered a case of compatible type 1 AIP without elevated levels of serum IgG4 or IgG4-positive plasma cells.This case suggests that AIP phenotypes are not always associated with IgG4.     

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.     

Histological diagnosis of autoimmune pancreatitis using EUS-guided trucut biopsy: a comparison study with EUS-FNA

Purpose  The aim of this study was to evaluate the feasibility and safety of endoscopic ultrasonography (EUS)-guided trucut biopsy (TCB) for diagnosis of autoimmune pancreatitis (AIP). Methods  Fourteen patients with suspected AIP based on imaging studies underwent both EUS-guided fine-needle aspiration (FNA) and EUS-TCB for diagnosis of AIP and exclusion of pancreatic cancer (PC). According to the revised Japanese clinical diagnostic criteria, AIP was diagnosed in eight while the remaining six patients had pancreatitis of other etiologies. Pathologically, AIP was defined as lymphoplasmacytic sclerosing pancreatitis (LPSP), and sub-divided into two types: definite LPSP (d-LPSP) showing fulspectrum of LPSP and probable LPSP (p-LPSP) without obliterative phlebitis or abundant (>10 cells/hpf) IgG4-positive plasmacytes infiltration. Results  PC was excluded in all patients. EUS-FNA resulted in three of eight patients with AIP were reported as p-LPSP, one was reported as normal, and 4 were inconclusive. One of six with non-autoimmune pancreatitis was diagnosed as p-LPSP on EUS-FNA, one as idiopathic chronic pancreatitis (ICP) and four were inconclusive. By using EUS-TCB, all AIP patients were diagnosed as LPSP (4 d-LPSP and 4 p-LPSP). Of the six patients with non-autoimmune pancreatitis, three were diagnosed as LPSP (1 d-LPSP and 2 p-LPSP) and three showed ICP on TCB. No complications were identified in any patient with either EUS-FNA or TCB. Conclusion  EUS-TCB is a safe and accurate procedure for obtaining a histological diagnosis in patients with suspected AIP. EUS-TCB can serve as a rescue technique in cases of AIP lacking typical findings.     

Mass‐forming type 1 autoimmune pancreatitis mimicking pancreatic cancer

We reported three cases of mass‐forming type 1 autoimmune pancreatitis (AIP) that were preoperatively suspected to be pancreatic cancer, and reviewed their clinicopathological features. Radiological findings in the patients revealed hypoattenuating masses in the early phase or a stricture of the main pancreatic duct with upstream dilatation, which was consistent with the diagnosis of pancreatic cancer. Histopathologically, the lesions were well demarcated and met all diagnostic criteria for immunoglobulin G4 (IgG4)‐related AIP, including the presence of periductal lymphoplasmacytic infiltration, obliterative phlebitis, storiform fibrosis and abundant IgG4‐positive plasma cells. However, the adjacent uninvolved pancreatic duct and lobular structures were well preserved. And in all patients, none or some of the aforementioned characteristics were observed. We suggest that some cases of focal AIP may progress to more severe grades and exhibit mass formation, although remaining localized. These focal cases of AIP are difficult to distinguish from pancreatic cancer. To our knowledge, this report is the first to present a histopathological comparison of mass‐forming AIP with the adjacent uninvolved pancreatic tissues.     

Steroid responsive pancreatic mass-forming type 2 autoimmune pancreatitis

Autoimmune pancreatitis (AIP) has two distinct subsets. Type 1 AIP or lymphoplasmacytic sclerosing pancreatitis is systemic disease with the elevation in serum levels of the IgG4. Type 2 AIP, also called duct-centric pancreatitis, features granulocyte epithelial lesions with duct obstruction in the pancreas without systemic involvement. Here, we report a case of type 2 AIP diagnosed by pathology, which is the first report in Korea. The case is a 56-year-old woman who presented with anorexia and vomiting. Computed tomography revealed mass-like lesion in the pancreatic head and the compression of the distal common bile duct and the head portion of the main pancreatic duct. Serum levels of the IgG4 were normal. Histologic examination revealed a dense neutrophil infiltration in the pancreatic parenchyme associated with extensive fibrosis, thereby confirming the diagnosis of type 2 AIP. The abnormalities in the clinical, laboratory, and radiological findings improved after oral steroid treatment.     

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

Background/aimsCoexistence 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.MethodsSerum 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.ResultsSerum 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.ConclusionsIn 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.     

Serum IgG4-negative autoimmune pancreatitis

Background  

Autoimmune pancreatitis (AIP) is considered to be a pancreatic lesion of IgG4-related systemic disease, but about 20% of AIP patients do not have elevated serum IgG4 levels. This study aimed to clarify the pathophysiology of AIP patients without elevated serum IgG4 levels.     

自身免疫性胰腺炎误诊误治17例临床分析

目的 总结自身免疫性胰腺炎(AIP)误诊误治的原因.方法 回顾性分析2005年5月至2010年7月间我院收治的17例有误诊误治经历的AIP患者的临床资料.结果 AIP的主要临床症状包括腹部轻度疼痛13例、进行性黄疸12例、发热6例、体重减轻9例.15例伴随一种或一种以上胰腺外脏器的自身免疫性疾病,包括过敏性鼻炎、颌下淋巴结肿大、颌下腺肿大、过敏性哮喘、类风湿性关节炎、干燥综合征、糖尿病、原发性硬化性胆管炎和自身免疫性肝炎.实验室检查方面,血清球蛋白增高11例、IgG增高14例、γ球蛋白增高13例、抗核抗体阳性13例、抗胰岛素IgG抗体阳性2例.影像学检查方面,胰腺弥漫性肿大15例,伴主胰管弥漫性狭窄或节段性狭窄、胰腺段胆总管狭窄、近端胆管扩张、胆囊增大;胰头、钩突局灶性肿大2例.17例中有13例误诊为胰腺癌,其中4例行胰十二指肠切除术,7例行胆肠吻合术,2例被认为肿瘤晚期失去治疗机会;4例被误诊为普通慢性胰腺炎.确诊AIP后,17例患者均接受糖皮质激素治疗,效果显著.随访6～45个月(平均15个月),4例复发,再次子糖皮质激素治疗效果好.随访期间未发现胰腺癌.结论 AIP 临床特点与胰腺癌相似,加之我国现阶段对AIP认识不足、重视不够,是导致误诊和误治的主要原因.

Abstract：

Objective To summarize the reasons of mis-diagnosis and mis-treatment of autoimmune pancreatitis (AIP). Methods Clinical data of 17 patients with AIP,who were admitted to the hospital from May 2005 to July 2010 and experienced mis-diagnosis and mis-treatment, were retrospectively analyzed. Results The main clinical manifestations included epigastric pain (13 cases),progressive obstructive jaundice (12 cases), fever (6 cases) and weight loss (9 cases). Fifteen patients had extrapancreatic organ involvemnet, including allergic rhinitis, swelling of lymphoglandulae submaxillares, swelling of submaxillary gland, allergic asthma, rheumatoid arthritis, Sjogren syndrome, diabetes mellitus, primary sclerosing cholangitis and autoimmune hepatitis. Of these 17 cases, 11 cases presented with high serum globulin, 14 cases with high serum IgG, 13 cases with high serum γ-globulin, 13 cases with positive anti-nuclear antibody and 2 cases with positive anti-insulin IgG antibody. The abdominal imaging demonstrated that 15 patients had diffuse enlargement of the pancreas with diffuse or segmental narrowing of main pancreatic duct, narrowing of the intrapancreatic common bile duct, dilation of the proximal biliary duct and gallbladder enlargement. Focal enlargement of the pancreas was found in 2 cases. Thirteen cases were misdiagnosed as pancreatic carcinoma. Among them, 4 cases underwent pancreaticoduodenectomy and 7 cases underwent choledochojejunostomy. Two cases were misdiagnosed as end stage of cancer that lost therapeutic chance. Another 4 cases were misdiagnosed as chronic pancreatitis. Steroid therapy was administered in all patients with satisfactory response. All patients were followed-up for 15 months (ranged from 6 months to 45 months), and recurrence was found in 4 cases. Satisfactory response was found in patients treated with steroid for the second time. No pancreatic cancer was found in these patients in the follow up period. Conclusion The main causes of mis-diagnosis and mis-treatment of AIP may be contributed by difficulty in differentiating AIP from pancreatic carcinoma based on clinical manifestations and inadequate knowledge of AIP as well as insufficient attention to AIP in China.