IgG4-positive plasma cell infiltration in the diagnosis of autoimmune pancreatitis

Lymphadenopathy of IgG4-related sclerosing disease

IgG4-related sclerosing disease is a recently recognized syndrome characterized by mass-forming lesions in exocrine glands or extranodal tissues due to lymphoplasmacytic infiltrates and sclerosis, a raised serum IgG4 level and increased IgG4+ plasma cells in the involved tissues. We report the morphologic features of the enlarged regional (n=3) and nonregional lymph nodes (n=3) in patients with this syndrome. The patients presented with autoimmune pancreatitis, lymphoplasmacytic sclerosing cholangitis, chronic sclerosing dacryoadenitis, or chronic sclerosing sialadenitis. The histologic features of the lymph nodes could be categorized into 3 patterns: Castleman diseaselike, follicular hyperplasia, and interfollicular expansion by immunoblasts and plasma cells. The percentage of IgG4+/IgG+ plasma cells was markedly elevated (mean 62% vs. 9.9% in 54 control lymph nodes comprising a wide variety of reactive conditions). We also report 6 cases of primary lymphadenopathy characterized by increased IgG4+/IgG+plasma cells (mean 58%). These cases share many clinical and pathologic similarities with IgG4-related sclerosing disease. In fact, 2 of these patients developed lymphoplasmacytic sclerosing cholangitis or lacrimal and submandibular gland involvement during the clinical course. These cases therefore probably represent primary lymph node manifestation of the disease. The importance of recognition of the lymphadenopathic form of IgG4-related sclerosing disease lies in the remarkable response to steroid therapy, and the potential of mistaking the disease for lymphoma either clinically or histologically.

Current diagnosis and management of unusual pancreatic tumors

BACKGROUND

The finding of a solid or cystic mass in the pancreas is becoming more common secondary to the increasing use of cross-sectional imaging and the improved sensitivity of such studies for the detection of pancreatic abnormalities. Because of the aggressive natural history of pancreatic cancer, this has caused concern that all pancreatic abnormalities may be cancer as well as confusion over proper diagnostic and treatment algorithms. This review provides an overview of the natural history, diagnostic considerations, and treatment recommendations for the less common tumors of the pancreas which can be misinterpreted as pancreatic cancer including: solid pseudopapillary tumors (SPT), acinar cell carcinoma (ACC), lymphoplasmacytic sclerosing pancreatitis (LPSP), primary pancreatic lymphoma (PPL), and metastatic renal cell carcinoma to the pancreas.

DATA SOURCES

A Medline search was conducted to identify studies investigating the clinicopathologic features, molecular genetics, pathogenesis, diagnosis, and treatment of SPT, ACC, LPSP, PPL, and pancreatic metastases.

CONCLUSIONS

It is often possible to obtain an accurate pretreatment diagnosis for these unusual pancreatic tumors and to successfully differentiate them from the more common pancreatic malignancies.

Update on the diagnosis and treatment of autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is the pancreatic manifestation of a systemic fibroinflammatory disease (IgG4-related systemic disease) in which affected organs demonstrate dense lymphoplasmacytic infiltration with abundant IgG4-positive cells. The diagnosis of AIP and its differentiation from pancreatic cancer, its main differential diagnosis, remains a clinical challenge. The five cardinal features of AIP are characteristic histology, imaging, and serology; other organ involvement; and response to steroid therapy. Recent advances in our understanding of these features have resulted in enhanced recognition and diagnosis of this benign disease. This in turn has resulted in the avoidance of unnecessary surgical procedures for suspected malignancy. This article reviews recent updates in the diagnosis and treatment of autoimmune pancreatitis.

Inflammatory abdominal aortic aneurysm: close relationship to IgG4-related periaortitis

Inflammatory abdominal aortic aneurysm (AAA) is a member of a family of disorders referred to as "chronic periaortitis" together with retroperitoneal fibrosis. Retroperitoneal fibrosis is included in IgG4-related disease, which is characterized by numerous infiltrating IgG4-positive plasma cells and high serum IgG4 concentrations. However, the relationship between IgG4-related disease and inflammatory AAA has not been documented. In this study, we examined the clinicopathologic characteristics of inflammatory (10 cases) and atherosclerotic (22 cases) AAAs, based on the hypothesis that inflammatory AAA might be related to IgG4-related disease. Cases of inflammatory AAA could be classified into 2 groups based on immunostaining of IgG4. Four patients showed diffuse infiltration of abundant IgG4-positive plasma cells (IgG4-related cases), whereas the remaining 6 cases of inflammatory AAA and all cases of atherosclerotic AAA had only a few IgG4-positive plasma cells (non-IgG4-related cases). IgG4-related inflammatory AAA was pathologically characterized by the frequent infiltration of eosinophils, lymph follicle formation, perineural inflammatory extension, and inconspicuous infiltration of neutrophils compared with non-IgG4-related inflammatory AAA. Obliterative phlebitis, which is venous occlusion with inflammatory cell infiltration, is observed in all IgG4-related cases. In addition, serum IgG4 concentrations were significantly higher in IgG4-related inflammatory AAA (109 to 559 mg/dL, normal range: 4 to 110 mg/dL) than non-IgG4-related inflammatory AAA (32 to 59 mg/dL) and all atherosclerotic AAA (12 to 83 mg/dL). In conclusion, inflammatory AAAs might be classified into 2 groups: IgG4-related or nonrelated. The former might be one of the IgG4-related diseases, and could be included in IgG4-related periaortitis together with retroperitoneal fibrosis.

Immunoglobulin G4-associated cholangitis: clinical profile and response to therapy

BACKGROUND & AIMS

Immunoglobulin (Ig)G4-associated cholangitis (IAC) is the biliary manifestation of a steroid-responsive multisystem fibroinflammatory disorder in which affected organs have a characteristic lymphoplasmacytic infiltrate rich in IgG4-positive cells. We describe clinical features, treatment response, and predictors of relapse in IAC and compare relapse rates in IAC with intrapancreatic vs proximal bile duct strictures.

METHODS

We reviewed clinical, serologic, and imaging characteristics and treatment response in 53 IAC patients.

RESULTS

IAC patients generally were older (mean age, 62 y) men (85%), presenting with obstructive jaundice (77%) associated with autoimmune pancreatitis (92%), increased serum IgG4 levels (74%), and abundant IgG4-positive cells in bile duct biopsy specimens (88%). At presentation, biliary strictures were confined to the intrapancreatic bile duct in 51%; the proximal extrahepatic/intrahepatic ducts were involved in 49%. Initial presentation was treated with steroids (n = 30; median follow-up period, 29.5 months), surgical resection (n = 18; median follow-up period, 58 months), or was conservative (n = 5; median follow-up period, 35 months). Relapses occurred in 53% after steroid withdrawal; 44% relapsed after surgery and were treated with steroids. The presence of proximal extrahepatic/intrahepatic strictures was predictive of relapse. Steroid therapy normalized liver enzyme levels in 61%; biliary stents could be removed in 17 of 18 patients. Fifteen patients treated with steroids for relapse after steroid withdrawal responded; 7 patients on additional immunomodulatory drugs remain in steroid-free remission (median follow-up period, 6 months).

CONCLUSIONS

IAC should be suspected in unexplained biliary strictures associated with increased serum IgG4 and unexplained pancreatic disease. Relapses are common after steroid withdrawal, especially with proximal strictures. The role of immunomodulatory drugs for relapses needs further study.

Autoimmune pancreatitis

Autoimmune pancreatitis is a form of chronic pancreatitis of presumed autoimmune aetiology. The disease is characterised with clinical, serological, histomorphological and imaging features. Autoimmune pancreatitis is recognised as a T-cell-mediated specific disease with lymphoplasmatic infiltration of pancreatic tissue and pancreatic parenchyma fibrosis. Serum immunoglobulin IgG or IgG4 and antibodies (rheumatoid factor, lactoferrin antibodies, carbonic anhydrase II, etc) are usually increased. But the lack of specific biochemical markers is a major drawback in the diagnosis of autoimmune pancreatitis. The Japan Pancreas Society proposed diagnostic criteria for autoimmune pancreatitis as the presence antibodies, pancreas enlargement and pancreatic duct narrowing, lymphoplasmatic infiltration, response to corticosteroid therapy, and association with other autoimmune diseases such as autoimmune hepatitis, sclerosing cholangitis, primary biliary cirrhosis, sialoadenitis, inflammatory bowel disease and Sjögren syndrome. New criteria (HISORt Criteria) incorporate imaging changes, organ involvement, specific elevation of IgG4 subclass and histopathological markers. Autoimmune pancreatitis could be associated with diabetes mellitus and exocrine pancreatic dysfunction. Clinically, autoimmune pancreatitis is a disease with mild symptoms; severe attacks of abdominal pain are not typical. Typically, pancreatic calcifications and pseudocyst are absent; on the other hand jaundice and/or pancreatic mass are frequent signs, and both make differential diagnosis with pancreatic cancer difficult. From a practical point of view, in an elderly male presenting with obstructive jaundice and pancreatic mass, autoimmune pancreatitis is one of the differential diagnoses to avoid unnecessary surgical therapy.

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, γ-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, the remaining 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. The differential diagnosis with high index of suspicion of AIP would improve the diagnostic accuracy for AIP.

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.

Pseudotumors due to IgG4 immune-complex tubulointerstitial nephritis associated with autoimmune pancreatocentric disease

Autoimmune pancreatitis (AIP) is a mass-forming chronic fibroinflammatory condition centered on the pancreatobiliary system and characterized by predominant immunoglobulin G4 (IgG4)-positive plasma cells. Recent reports have brought to light the multiorgan involvement of this disease. We describe a series of 5 cases of tubulointerstitial nephritis (TIN) associated with AIP and characterize the clinical, pathologic, ultrastructural, and immunopathologic features of TIN. The specimens consisted of 4 biopsies and 1 nephrectomy. The average patient age was 64 years (range 45 to 78) and the male to female ratio was 4:1. All had histologic and/or clinical and radiographic evidence of AIP, mass-forming sclerosing cholangitis, or both. The clinical impression in 4 patients was a renal mass or vasculitis. Two patients had renal insufficiency. Histologic preparations revealed a dense tubulointerstitial lymphoplasmacytic infiltrate. Eosinophils were often numerous. Tubulitis and tubular injury were present, along with tubular atrophy with focally thickened tubular basement membranes (TBMs). The histologic appearance ranged from a cellular, inflammatory pattern without tubular atrophy to a striking expansive interstitial fibrosis with tubular destruction. The nephrectomy specimen demonstrated a masslike nodular pattern of inflammation with normal renal tissue elsewhere. Glomeruli were uninvolved. By immunohistochemistry or immunofluorescence, numerous plasma cells in the infiltrate were positive for IgG4. TBM granular IgG deposits, predominantly of the IgG4 subclass, were detected in 4 of 5 cases by either immunofluorescence or immunohistochemistry. By electron microscopy, corresponding amorphous electron-dense deposits were present in the TBM in these cases. This type of TIN, typically characterized by a masslike lesion consisting of a lymphoplasmacytic infiltrate with eosinophils and prominent IgG4-positive plasma cells and immune-complex deposits in the TBM, may be part of a systemic IgG4-related disease, which we term "IgG4-associated immune complex Multiorgan Autoimmune Disease" (IMAD).

Idiopathic retroperitoneal fibrosis: clinicopathologic features and differential diagnosis

Idiopathic retroperitoneal fibrosis (IRF) is a rare disease often causing obstructive uropathy. We evaluated the clinicopathologic features of 24 patients with IRF to characterize the histopathology of the disease and to provide a framework for the differential diagnosis with other retroperitoneal fibrosing conditions. Retroperitoneal specimens were analyzed by light and electron microscopy and by immunohistochemistry. Most patients presented with abdominal/lumbar pain, constitutional symptoms, and high acute-phase reactants. Overall, 20 had ureteral involvement and 13 developed acute renal failure. The retroperitoneal tissue consisted of a fibrous component and a chronic inflammatory infiltrate with the former characterized by myofibroblasts within a type-I collagen matrix. The infiltrate displayed perivascular and diffuse patterns containing lymphocytes, macrophages, plasma cells, and eosinophils. The perivascular aggregates had a central core of CD20(+) cells and a mantle of CD3(+) cells in equal proportions. In the areas of diffuse infiltrate, CD3(+) cells outnumbered the CD20(+) cells. Most plasma cells were positive for the IgG4 isotype. Small vessel vasculitis was found in the specimens of 11 patients. Our study indicates that a sclerotic background with myofibroblasts associated with a diffuse and perivascular infiltrate mainly consisting of T and B lymphocytes may be a pathological hallmark of IRF.

Autoimmune pancreatitis

Autoimmune pancreatitis is a rare systemic fibrotic inflammatory disorder that can affect organs such as the bile ducts, salivary glands, and retroperitoneal lymph nodes, in addition to the pancreas. Morphological characteristics of autoimmune pancreatitis include a diffusely enlarged 'sausage-shaped' pancreas and an irregularly narrowed duct of Wirsung. According to the revised Japan Pancreas Society criteria, the diagnosis of autoimmune pancreatitis requires that one or more secondary serologic or histologic criteria are also met: the presence of autoantibodies, elevated levels of gamma-globulins, IgG or IgG(4), a lymphoplasmacytic infiltrate, or pancreatic fibrosis. The presence in any affected organ of a lymphoplasmacytic inflammatory infiltrate containing greater than 10 IgG(4)-positive cells per high-power field is pathognomonic for autoimmune pancreatitis. Precise data on the incidence and prevalence of autoimmune pancreatitis are currently not available because most reports involve either limited patient series or resection specimen cohorts. New diagnostic tools and further studies of the underlying pathophysiology and prognosis of autoimmune pancreatitis are needed for adequate and effective treatment strategies to be developed. The most crucial issue when caring for patients with suspected autoimmune pancreatitis is to differentiate autoimmune pancreatitis from pancreatic carcinoma, because pancreatic carcinoma requires surgery, whereas autoimmune pancreatitis responds well to steroid treatment.

Autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a benign, IgG4-related, fibroinflammatory form of chronic pancreatitis that can mimic pancreatic ductal adenocarcinoma both clinically and radiographically. Laboratory studies typically demonstrate elevated serum IgG4 levels and imaging studies reveal a diffusely or focally enlarged pancreas with associated diffuse or focal narrowing of the pancreatic duct. The pathologic features include periductal lymphoplasmacytic inflammation, obliterative phlebitis, and abundant IgG4-positive plasma cells. The treatment of choice for AIP is steroid therapy. Diagnostic criteria for AIP have been proposed that incorporate histologic, radiographic, serologic, and clinical information.

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

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

IgG4-related autoimmune prostatitis: two cases with or without autoimmune pancreatitis

Recently, autoimmune pancreatitis (AIP) has been reported with a variety of extra-pancreatic manifestations and infiltration of IgG4-positive cells into the affected organs. We report herein two cases with prostatitis. One was seen in a patient with typical AIP, and the other was observed without any clinical manifestation of AIP. Serum IgG4 levels were elevated in both cases. Histological examination of the prostates showed that parenchymal cells were partially or totally replaced with fibrosis and abundant infiltration of IgG4-positive cells. Significant uptake of [18F] fluorodeoxyglucose by the prostate was seen in both cases. In the case with AIP, the uptake completely disappeared after steroid therapy. The findings observed in these cases suggest that the pathological mechanism for prostatitis is similar to the mechanism previously implicated in AIP, namely IgG4-related autoimmune prostatitis.