Biliary and hepatic involvement in IgG4-related disease

Mimickers of immunoglobulin G4-related hepatobiliary disease on biopsy

With the growing recognition of IgG4-related hepatobiliary disease, establishing a definitive diagnosis relies mainly on a combination of clinical findings, serological markers, and imaging modalities. However, the role of histopathological evaluation remains indispensable, particularly in cases necessitating differential diagnosis or malignancy exclusion. While diagnosing IgG4-related hepatobiliary disease through surgical resection specimens is often straightforward, pathologists encounter substantial challenges when evaluating biopsies. The increasing rarity of surgical interventions exacerbates this due to improved disease recognition and suspicion. Numerous confounding factors, including the absence of the characteristic histologic features, limited tissue sample size, biopsy artifacts, and the limited value of IgG4 counts, further complicate the diagnostic process. Additionally, many other disorders exhibit clinical and histological features that overlap with IgG4-related disease, intensifying the complexity of interpreting biopsy specimens. This article explores the clinical and histomorphologic features of IgG4-related hepatobiliary disease and its potential mimickers. It offers valuable insights for pathologists and clinicians when confronted with biopsy specimens from hepatobiliary organs.

Pediatric IgG4-related disease: a descriptive review

INTRODUCTION

IgG4-related disease (IgG4-RD) is an immune-mediated systemic fibroinflammatory condition characterized by serum IgG4 elevation and IgG4-positive plasma cell infiltration into various organs. It generally occurs in elderly males. Pediatric cases have been reported, albeit rarely, accordingly lack of recognition of such cases could delay therapeutic intervention leading to poorer outcomes.

AREAS COVERED

The present review is a descriptive review of all published case reports, cohort studies, and reviews of pediatric IgG4-RD listed in PubMed. Characteristics of pediatric IgG4-RD were clarified, including sex, organ involvement, serological and histological findings, and treatment. We assessed how many published cases met current classification and comprehensive diagnostic criteria.

EXPERT OPINION

The characteristics of pediatricIgG4-RD differed from adult IgG4-RD in terms of sex and involved organs. There was no clear male dominance in numbers of cases, and surface organ involvement such as ophthalmic diseases were more common in the pediatric IgG4-RD. Organ involvement tended to be indolent and unilateral, causing difficulty in definitively diagnosing pediatric IgG4-RD. Only about 20% of published cases met IgG4-RD classification or comprehensive diagnostic criteria. Physicians should be careful in diagnosing pediatric IgG4-RD after excluding mimickers. International collaboration toward high-quality evidence to support diagnosis and treatment of pediatric IgG4-RD is advised.

Inflammasome and pyroptosis in autoimmune liver diseases

Autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and IgG4-related sclerosing cholangitis (IgG4-SC) are the four main forms of autoimmune liver diseases (AILDs), which are all defined by an aberrant immune system attack on the liver. Most previous studies have shown that apoptosis and necrosis are the two major modes of hepatocyte death in AILDs. Recent studies have reported that inflammasome-mediated pyroptosis is critical for the inflammatory response and severity of liver injury in AILDs. This review summarizes our present understanding of inflammasome activation and function, as well as the connections among inflammasomes, pyroptosis, and AILDs, thus highlighting the shared features across the four disease models and gaps in our knowledge. In addition, we summarize the correlation among NLRP3 inflammasome activation in the liver-gut axis, liver injury, and intestinal barrier disruption in PBC and PSC. We summarize the differences in microbial and metabolic characteristics between PSC and IgG4-SC, and highlight the uniqueness of IgG4-SC. We explore the different roles of NLRP3 in acute and chronic cholestatic liver injury, as well as the complex and controversial crosstalk between various types of cell death in AILDs. We also discuss the most up-to-date developments in inflammasome- and pyroptosis-targeted medicines for autoimmune liver disorders.

Post-ERCP pancreatitis occurs more frequently in self-expandable metallic stents than multiple plastic stents on benign biliary strictures: a meta-analysis

BACKGROUND

The occurrence of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) after using covered self-expandable metallic stents (CSEMS) and multiple plastic stents (MPS) in the therapy of benign biliary strictures (BBS) remains ambiguous, this analysis aimed to evaluate the outcomes.

CONCLUSIONS

Compared with MPS, CSEMS caused a significantly higher incidence of PEP but fewer ERCP procedures, while the rate of stricture resolution, recurrence, and overall adverse events were comparable. Prevention methods of PEP should be further evaluated in BBS when undergoing CSEMS placement.

METHODS

A systematic search of electronic databases (PubMed, Web of Science and Cochrane Library) was conducted for randomised controlled trials (RCTs), and the included studies were published between 2008 and 2021. The primary outcome was PEP, while the secondary outcomes were stricture resolution, recurrence, overall adverse events, costs, and ERCP sessions. Pooled effect sizes were calculated with the random-effects model or fixed-effects model depending on the heterogeneity.

RESULTS

Six RCTs contained 444 patients (221 with CSEMS, 223 with MPS) finally included in the meta-analysis. The present analysis shows that compared to MPS, PEP is more likely to occur in CSEMS (OR [odds ratio] = 3.34, 95% confidence intervals [CI]:1.44-7.77, p = .005). CSEMS needs fewer ERCP sessions (Mean Deviation [MD]: -1.56; 95%CI:-2.66, -0.46], p = .006). The difference in stricture resolution and recurrence was not significant between the two stent types (OR = 0.87, 95%CI: 0.49-1.56, p = .64; and OR = 2.3, 95%CI: 0.68-7.76, p = .18). The incidence of overall adverse events was comparable between CSEMS and the MPS group (OR = 1.49, 95% CI: 0.97-2.29, p = .07).

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42022314864. Key messagesCSEMS and MPS placement remain a mainstay for patients with BBS, and severe complications after stent placement have not been compared.The incidence of PEP was higher after deployment of CSEMS compared to MPS.Prevention methods of PEP should be evaluated in BBS when undergoing CSEMS placement.

Isolated IgG4 Autoimmune Cholangitis in the Absence of Pancreatitis

The IgG4-related disease is an uncommon immune-mediated condition affecting multiple organ systems concomitantly; however, it is very rare for a patient to have isolated IgG4 autoimmune cholangitis or IgG4-related disease confined to the hepatobiliary system. The majority of cases are associated with pancreatitis and are incidentally discovered in the workup of acute or chronic pancreatitis. When it affects the hepatobiliary system, it develops as inflammatory fibrosclerosing cholangitis, which can mimic other hepatobiliary diseases such as primary sclerosing cholangitis. Herein, we present a case of type 1 IgG4 autoimmune cholangitis in the absence of pancreatitis. Our case is particularly unique because type 1 is the most common type associated with autoimmune pancreatitis; however, our patient had type 1 without any evidence of pancreatic involvement. Additionally, like most cases of isolated IgG4 autoimmune cholangitis, our patient was refractory to standard therapy. This case highlights the clinical significance, rarity and severity of isolated IgG4 autoimmune cholangitis.

Isolated mass-forming IgG4-related sclerosing cholangitis masquerading as extrahepatic cholangiocarcinoma: A case report

BACKGROUND

IgG4-related sclerosing cholangitis (IgG4-RSC) is an uncommon benign disease, and its rarer, isolated and mass-forming subtype poses a significant challenge to differential diagnosis from cholangiocarcinoma of the extrahepatic bile duct. We herein report a case of isolated IgG4-RSC with an obstructing bile duct mass, for which extrahepatic bile duct resection was performed under the impression of proximal common bile duct (CBD) cancer.

CASE SUMMARY

A 79-year-old male was admitted for jaundice that had developed 1 mo prior. There was no family history for autoimmune diseases or biliary cancer. Computed tomography (CT) and magnetic resonance cholangiopancreaticography revealed a short segmental concentric wall thickening of the proximal CBD with diffuse dilatation of the bile duct to the periphery. The endoscopic biopsy specimen showed no malignant cells. Positron emission tomography-CT showed a focal hypermetabolic lesion (SUVmax 4.2) in and around the proximal CBD area. With the impression of proximal CBD cancer, we performed segmental resection of the extrahepatic bile duct. Histopathology demonstrated marked sclerosis with diffuse lymphoplasmacytic infiltration and some eosinophils. Immunohistochemical staining for IgG4 showed increased positivity in some areas (up to 30/high-power field) and IgG4+/IgG+ cell ratio as 30%-50%. Pathologists’ impression was IgG4-related sclerosing disease. Follow-up serum IgG4 levels were continuously elevated; however, no evidence of relapse or other organ involvement related to IgG4-RSC presented.

CONCLUSION

Isolated and mass-forming IgG4-RSC displays striking similarity with cholangiocarcinoma. To avoid unnecessary major surgery, high index of suspicion is needed.

Differences in Clinical Features and Diagnostic Strategies Between IgG4-Related Autoimmune Cholangitis and Cholangiocarcinoma

IgG4-related autoimmune cholangitis (IgG4-AIC) is often difficult to distinguish from cholangiocarcinoma (CCA). This study aimed to determine a practical clinical strategy for distinguishing between IgG4-AIC and CCA to avoid unnecessary surgical resection. We retrospectively collected and compared the clinicopathological data between IgG4-AIC and CCA patients, including the clinical, serological, and radiological characteristics, to follow up on these patients to investigate the prognosis. Among the 377 patients who received surgical resection for suspecting CCA at the Sun Yat-Sen Memorial Hospital between June 2004 and June 2014, 14 patients were diagnosed as IgG4-AIC through histochemistry after surgery. Immunohistochemistry revealed that IgG4 was up-regulated in the plasma cells of IgG4-AIC tissues in 13 out of 14 patients. The serum CA19-9 level was significantly lower than in the CCA group. Patients with IgG4-AIC can only see slight or no enhancement under the contrast enhancement CT scan, while there are no signs of ring-like or delayed enhancement that is unique to CCA. Thirteen patients were followed up, and the time was 12 to 92 months. Three of them were regularly treated with prednisone after surgery, and original symptoms disappeared. Our study demonstrated that the combination of imaging with serum CA19-9 could improve the preoperative diagnostic value and reduce the rate of unnecessary resection.

Immunoglobulin G4-associated autoimmune hepatitis with peripheral blood eosinophilia: a case report

Background

Immunoglobulin G4 (IgG4) associated autoimmune hepatitis (AIH) has been recognized as a type of autoimmune disease that responds to corticosteroid. The diagnosis is based on elevation of the serum IgG4 level, abundance of IgG4 enhanced plasma cell infiltration in the portal region of the liver, and satisfaction of the criteria for “definite AIH” under the revised International Autoimmune Hepatitis Group (IAIHG) scoring system. However, the clinical course of the disease is unclear.

Case presentation

A 65-year-old man with jaundice and peripheral blood eosinophilia. His IAIHG and simplified score was compatible with definite AIH and his IgG4 level was elevated. Magnetic resonance imaging did not reveal abnormalities in the hepatobiliary system or pancreas. A liver biopsy revealed interface hepatitis with IgG4 positive plasma cell infiltration in the portal region, without evidence of bile duct injury. He responded to 4-week period of induction prednisolone therapy and had no recurring symptoms under maintenance therapy of 5 mg prednisolone during the 3-year follow up.

Conclusions

This was a rare case that demonstrated an association between IgG4 associated AIH and the presence of peripheral blood eosinophilia.

IgG4-related disease with multiple organs involvement was effectively controlled by glucocorticoids: a case report

Immunoglobulin G4 (IgG4) related disease is a rare autoimmune disease involving multiple organs and tissues. A diagnosis of IgG4-related disease (IgG4-RD) is mainly based on serum IgG4 concentration, imaging, pathology, and effective glucocorticoids therapy. In this paper, we report a 53-year-old male with typical signs and symptoms of IgG4-RD successfully treated with glucocorticoids. This patient had experienced bilateral mumps for more than 8 months and intermittent abdominal pain spreading to his lower back for 2 months before his admission. During his hospitalization, based on the characteristic appearance of magnetic resonance imaging (MRI), magnetic resonance cholangiopancreatography (MRCP), and computed tomography with positron emission tomography, a diagnosis of autoimmune pancreatitis (AIP), cholangitis with biliary obstruction, lachrymal adenitis, and submandibular adenitis was made. A high serum IgG4 concentration further supported a diagnosis of IgG4-RD. Then, the treatment was promptly initiated with corticosteroids. MRI, MRCP, and IgG4 concentration were re-examined during his follow up, suggesting that glucocorticoid treatment resulted in a resolution of his disease. The dosage of glucocorticoid had been gradually decreased. Now, he is stable with oral low-dose glucocorticoids. Certainly, long-term follow up of this patient with such a rare disease is very essential to observe the possibility of disease recurrence and glucocorticoids related complications.

Difficulty in differentiating between IgG4-related hepatic inflammatory pseudotumor and intrahepatic cholangiocarcinoma

A 71-year-old man on prednisolone for immunoglobulin (Ig) G4-related renal disease showed increased carbohydrate antigen (CA) 19–9 level; abdominal enhanced computed tomography (CT) showed a lesion in the left lateral segment and dilatation of the peripheral biliary duct. He was referred to our hospital for detailed examination for suspected intrahepatic cholangiocarcinoma. CT and magnetic resonance imaging findings were similar to those for intrahepatic cholangiocarcinoma. However, endoscopic retrograde cholangiopancreatography showed a smooth narrowing of the bile duct which suggested inflammatory disease. Liver biopsy was performed; IgG4-related hepatic inflammatory pseudotumor (IPT) was diagnosed. IgG4-related hepatic IPTs are rare diseases that develop in association with the development of sclerosing cholangitis. Most of these lesions develop in the hepatic hilum and the imaging findings of these tumors are similar to those of hilar cholangiocarcinomas. Thus, hepatic IPTs are difficult to differentiate from malignancy; in some cases, surgical resection has been considered for establishing the diagnosis. In the present case, we could diagnose hepatic IPT on the basis of liver biopsy, which is the recommended approach in cases of suspected hepatic IPT.

IgG4-Related Sclerosing Cholangitis: A Clinical and Imaging Review

OBJECTIVE. The purpose of this article is to present the pathologic and clinical features of IgG4-related sclerosing cholangitis (ISC), illustrate the associated imaging findings, and discuss treatment of the disorder. CONCLUSION. ISC is an inflammatory disorder involving the biliary system and resulting in strictures. Although often associated with autoimmune pancreatitis, it may be an isolated disease. Differentiation of ISC from other forms of cholangitis and cholangiocarcinoma is difficult but necessary for management. Imaging is important in diagnosing and assessing the extent of disease and planning a management strategy.

Autoimmune hepatitis and IgG4-related disease

IgG4-related disease (IgG4-RD) is a chronic-fibroinflammatory disorder affecting a wide range of organs. Elevation of serum IgG4 concentrations and abundant infiltration of IgG4-expressing plasma cells are key diagnostic features of this autoimmune disease. Although common organ involvement of IgG4-RD includes the salivary glands, pancreas, and bile duct, hepatic involvement is less well established. Recently, five studies identified a subtype of autoimmune hepatitis (AIH), called IgG4-associated AIH (IgG4-AIH). IgG4-AIH is diagnosed based on significant accumulation of IgG4-expressing plasmacytes in the liver in patients who met the diagnostic criteria for classical AIH. Although four of the five reports regarded IgG4-AIH based on hepatic accumulation of IgG4-positive cells alone, one report diagnosed IgG4-AIH based on both hepatic accumulation of IgG4-positive cells and elevated serum concentrations of IgG4. IgG4-AIH diagnosed based on the latter criteria may be a hepatic manifestation of IgG4-RD whereas IgG4-AIH diagnosed based on the former criteria may be a subtype of AIH. In this review article, we summarize and discuss clinicopathological features of IgG4-AIH.

Imaging in Autoimmune Pancreatitis and Immunoglobulin G4-Related Disease of the Abdomen

Autoimmune pancreatitis (AIP) is steroid-responsive fibroinflammatory disorder of the pancreas. There are 2 distinct subtypes of AIP, types 1 and 2. Type 1 is associated with systemic immunoglobulin (Ig)G4 disease and may affect multiple organs in the body. Type 2 is confined to the pancreas and shows an association with ulcerative colitis. This article describes the imaging findings of AIP and IgG4 disease in the liver, bile ducts, kidneys, and the retroperitoneal regions. The imaging differentiation of AIP from pancreas cancer is discussed.

Immunoglobulin G4-related sclerosing cholangitis

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory condition of which IgG4-related sclerosing cholangitis (IgG4-SC) is the biliary manifestation. In this review, we provide an overview of IgG4-RD, with a focus on the biliary manifestations. In particular, we describe the important differential diagnoses of IgG4-SC, namely, primary sclerosing cholangitis and cholangiocarcinoma, outline diagnostic criteria for IgG4-SC, provide insight into possible pathophysiological mechanisms underlying the disease and discuss short and long-term management options of this recently described disease.

Evaluation of IgG4 levels as a fibrosis marker on disease activity in the course of hepatitis B infection

Aim: Understanding immunopathogenesis of hepatitis-B virus (HBV) infection is pivotal in the management of complications. The aim of the study is to investigate the association of IgG4 levels with the liver fibrosis. Methods: Histological evaluation of the liver biopsy and laboratory analyses including IgG4 were performed. Results: A total of 130 patients fulfilling the criteria for a diagnosis of HBV infection were enrolled in the study. Of these patients, 14 had HBeAg positive and 116 had HBeAg negative HBV infection. In HBeAg-positive patients serum IgG4 levels were significantly higher than HBeAg-negative patients (p = 0.038). Conclusion: There is an association of IgG4 level and higher rates of viral replication and enhanced infectivity.

Hepatic actinomycosis with immunoglobulin G4-related liver disease: A case report

RATIONALE

Immunoglobulin (Ig)G4-related pseudotumors of the liver are very rare diseases that are difficult to distinguish from malignant tumors. They can be usually improved by steroid therapy. Actinomycosis is a chronic, suppurative, granulomatous infection, for which immune suppression is a predisposing factor. It can also mimic malignant tumors.

PATIENT CONCERNS

A 67-year-old man presented with mild abdominal discomfort and a 5-kg weight loss for 3 months. Initially, he visited another hospital and was treated with antibiotics under the assumption of a liver abscess. Symptom was not resolved.

DIAGNOSES

He diagnosed as having an IgG4-related pseudotumor of the right lobe of the liver after liver biopsy. Despite 2 months of steroid therapy, the liver mass was aggravated and invaded the right lung, as observed on follow-up computed tomography scan.

INTERVENTIONS

We performed en bloc resection of the tumor under the assumption that it was a malignant tumor.

OUTCOMES

The pathology of the tumor was revealed as actinomycotic colonies and IgG4-positive plasma cells of the liver. He recovered well and was discharged with ursodeoxycholic acid tablet for 14 days. After 3 months, he underwent postoperative follow-up CT and there was no remarkable finding in remnant left hepatic lobe.

LESSONS

Hepatic actinomycosis and IgG4-related pseudotumors of the liver are both difficult to diagnose. As in our patient, combined diseases are more difficult to diagnose and to determine the optimal treatment. Since immunosuppression therapy of autoimmune diseases can cause and aggravate infection, management must be approached carefully. We can learn that various possibilities must be considered before diagnosing and treating a hepatic mass.

IgG4-Related Cholangiopathy and Its Mimickers: A Case Report and Review Highlighting the Importance of Early Diagnosis

Immunoglobulin (Ig) G4 (IgG4)-related disease is a recently described clinical entity that can involve multiple organs. It is an autoimmune disorder characterized by a dense lymphoplasmacytic infiltrate, storiform fibrosis, and obliterative phlebitis. A key distinguishing factor is its dramatic response to steroid therapy. Although best described in cases of autoimmune pancreatitis, IgG4-related disease has also been implicated in patients with cholangitis and is now commonly referred to as IgG4-related cholangiopathy. It is characterized by elevated serum IgG4 levels, an IgG4-positive plasma cell infiltration with storiform fibrosis/obliterative phlebitis of the bile duct wall, and a response to steroids. It is crucial to differentiate IgG4-related cholangiopathy from its mimickers, such as primary biliary cholangitis, secondary biliary cholangitis, primary sclerosing cholangitis, secondary sclerosing cholangitis, and cholangiocarcinoma, because treatment modalities and outcomes of IgG4-related cholangiopathy differ significantly from these disorders. Here, we present an interesting case of IgG4-related cholangiopathy, discuss clinical and pathological features crucial to its early diagnosis, and compare and contrast this condition with its potentially confounding mimickers.

Eosinophilic cholangitis is a potentially underdiagnosed etiology in indeterminate biliary stricture

AIM

To investigate presence and extent of eosinophilic cholangitis (EC) as well as IgG4-related disease in patients with indeterminate biliary stricture (IBS).

METHODS

All patients with diagnosis of sclerosing cholangitis (SC) and histopathological samples such as biopsies or surgical specimens at University Hospital Frankfurt from 2005-2015 were included. Histopathological diagnoses as well as further clinical course were reviewed. Tissue samples of patients without definite diagnosis after complete diagnostic work-up were reviewed regarding presence of eosinophilic infiltration and IgG4 positive plasma cells. Eosinophilic infiltration was as well assessed in a control group of liver transplant donors and patients with primary sclerosing cholangitis.

RESULTS

one hundred and thirty-five patients with SC were included. In 10/135 (13.5%) patients, no potential cause of IBS could be identified after complete diagnostic work-up and further clinical course. After histopathological review, a post-hoc diagnosis of EC was established in three patients resulting in a prevalence of 2.2% (3/135) of all patients with SC as well as 30% (3/10) of patients, where no cause of IBS was identified. 2/3 patients with post-hoc diagnosis of EC underwent surgical resection with suspicion for malignancy. Diagnosis of IgG4-related cholangitis was observed in 7/135 patients (5.1%), whereas 3 cases were discovered in post-hoc analysis. 6/7 cases with IgG4-related cholangitis (85.7%) presented with eosinophilic infiltration in addition to IgG4 positive plasma cells. There was no patient with eosinophilic infiltration in the control group of liver transplant donors (n = 27) and patients with primary sclerosing cholangitis (n = 14).

CONCLUSION

EC is an underdiagnosed benign etiology of SC and IBS, which has to be considered in differential diagnosis of IBS.

Immunoglobulin G4-Related Disease: Recent Advances in Pathogenesis and Imaging Findings

Immunoglobulin G4-related disease (IgG4-RD) is a novel, immune-mediated, multisystem disease characterized by the development of tumefactive lesions in multiple organs. IgG4-RD encompasses many fibroinflammatory diseases that had been thought to be confined to single organs. Delayed diagnosis or misdiagnosis as malignancies leading to aggressive treatment may be averted by identification of the multisystem nature of IgG4-RD. Most cases show exquisite response to steroid therapy; steroid-resistant cases are being treated by novel therapeutic agents, including B-cell depleting agents such as rituximab. Cross-sectional imaging studies play a pivotal role in the initial diagnosis, assessing response to therapy and long-term surveillance.

IgG4-related hepatobiliary disease: an overview

IgG4-related hepatobiliary diseases are part of a multiorgan fibroinflammatory condition termed IgG4-related disease, and include IgG4-related sclerosing cholangitis (IgG4-SC) and IgG4-related hepatopathy. These diseases can present with biliary strictures and/or mass lesions, making them difficult to differentiate from primary sclerosing cholangitis (PSC) or other hepatobiliary malignancies. Diagnosis is based on a combination of clinical, biochemical, radiological and histological findings. However, a gold standard diagnostic test is lacking, warranting the identification of more specific disease markers. Novel assays - such as the serum IgG4:IgG1 ratio and IgG4:IgG RNA ratio (which distinguish IgG4-SC from PSC with high serum IgG4 levels), and plasmablast expansion to recognize IgG4-SC with normal serum IgG4 levels - require further validation. Steroids and other immunosuppressive therapies can lead to clinical and radiological improvement when given in the inflammatory phase of the disease, but evidence for the efficacy of treatment regimens is limited. Progressive fibrosclerotic disease, liver cirrhosis and an increased risk of malignancy are now recognized outcomes. Insights into the genetic and immunological features of the disease have increased over the past decade, with an emphasis on HLAs, T cells, circulating memory B cells and plasmablasts, chemokine-mediated trafficking, as well as the role of the innate immune system.

Imaging features of immunoglobulin G4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition that was first recognised as a systemic disease in 2003, when patients with autoimmune pancreatitis were found to have extrapancreatic manifestations. Since 2003, IgG4-RD has been described in a diverse range of other organs including the biliary tree, orbits, lacrimal glands, salivary glands, lungs, kidneys, aorta, retroperitoneum, lymph nodes, pachymeninges, prostate and pituitary gland. The disease frequently occurs in the absence of pancreatic involvement. The imaging manifestations of IgG4-RD are broad and variable depending on the organ involved. The majority of individual organ appearances are non-specific and differentiation between IgG4-RD and potentially more serious conditions is not usually possible based on radiological findings in one organ alone. However, if there are simultaneous findings typical of IgG4-RD in multiple organs then this is a key diagnostic clue and IgG4-RD should be considered as one of the main differentials. This review article examines the spectrum of imaging appearances of IgG4-RD. Increased awareness of the spectrum of radiological appearances of IgG4-RD throughout the body and subsequent consideration of the condition may potentially avoid invasive treatment and lead to more prompt corticosteroid therapy.

Controversies in the management of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) remains a rare but significant disease, which affects mainly young males in association with inflammatory bowel disease. There have been few advances in the understanding of the pathogenesis of the condition and no therapeutics with proven mortality benefit aside from liver transplantation. There remain areas of controversy in the management of PSC which include the differentiation from other cholangiopathies, in particular immunoglobulin G4 related sclerosing cholangitis, the management of dominant biliary strictures, and the role of ursodeoxycholic acid. In addition, the timing of liver transplantation in PSC remains difficult to predict with standard liver severity scores. In this review, we address these controversies and highlight the latest evidence base in the management of PSC.

Immunology of IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition that derives its name from the characteristic finding of abundant IgG4(+) plasma cells in affected tissues, as well as the presence of elevated serum IgG4 concentrations in many patients. In contrast to fibrotic disorders, such as systemic sclerosis or idiopathic pulmonary fibrosis in which the tissues fibrosis has remained largely intractable to treatment, many IgG4-RD patients appear to have a condition in which the collagen deposition is reversible. The mechanisms underlying this peculiar feature remain unknown, but the remarkable efficacy of B cell depletion in these patients supports an important pathogenic role of B cell/T cell collaboration. In particular, aberrant T helper type 2 (Th2)/regulatory T cells sustained by putative autoreactive B cells have been proposed to drive collagen deposition through the production of profibrotic cytokines, but definitive demonstrations of this hypothesis are lacking. Indeed, a number of unsolved questions need to be addressed in order to fully understand the pathogenesis of IgG4-RD. These include the identification of an antigenic trigger(s), the implications (if any) of IgG4 antibodies for pathophysiology and the precise immunological mechanisms leading to fibrosis. Recent investigations have also raised the possibility that innate immunity might precede adaptive immunity, thus further complicating the pathological scenario. Here, we aim to review the most recent insights on the immunology of IgG4-RD, focusing on the relative contribution of innate and adaptive immune responses to the full pathological phenotype of this fibrotic condition. Clinical, histological and therapeutic features are also addressed.