IgG4-Related Sclerosing Cholangitis and Primary Sclerosing Cholangitis

Beyond cholangiocarcinoma: imaging features of mimicking pathologies in the biliary tract

Cholangiocarcinoma (CCA) is the second most common primary malignancy of the hepatobiliary system and presents as a heterogeneous disease with three distinct morphological subtypes: mass-forming, periductal-infiltrating, and intraductal-growing, each characterized by distinguishing imaging features. Accurate diagnosis of CCA is challenging due to the overlap of imaging findings with a broad range of benign and malignant conditions. Therefore, it is essential for radiologists to recognize these mimickers and offer a reasonable differential diagnosis, as this has a significant impact on patient management. Although histopathological confirmation is often required for a definitive diagnosis, understanding specific imaging characteristics that differentiate CCA from its mimickers is crucial. This article highlights a variety of benign and malignant conditions that resemble CCA on imaging, emphasizing features that enhance diagnostic accuracy in clinical practice.

Autoimmune Biliary Diseases: A Review of Primary Biliary Cholangitis, Primary Sclerosing Cholangitis, Immunoglobulin G4-Related Sclerosing Cholangitis, and Autoimmune Hepatitis

Autoimmune and immune-mediated biliary diseases represent a small proportion of biliary disorders, but owing to their progressive nature, lead to end-stage liver disease, necessitating liver transplantation for definitive management.

IgG4-related disease mimicking a liver abscess

IgG4-related disease (IGRD) is a complex medical condition affecting multiple organs, including the liver. The condition is characterized by excessive production of IgG4 antibodies, leading to chronic inflammation and tissue damage. We present a case of a 37-year-old man with a history of chronic pancreatitis was diagnosed with a liver mass. Initial treatment included piperacillin and tazobactam, but the patient's condition worsened. An ultrasound-guided biopsy revealed increased IgG4 positive cells, leading to the diagnosis of an inflammatory pseudotumor associated with IGRD. The patient was treated with prednisone taper therapy, and the liver mass resolved after six months of corticoid treatment.

A Review of IgG4-related Sclerosing Cholangitis (IgG4-SC)

IgG4-related sclerosing cholangitis (IgG4-SC) is a unique, steroid-responsive, fibroinflammatory condition that is more commonly found in older men and is strongly associated with autoimmune pancreatitis (AIP). It may pose a diagnostic challenge at times due to closely mimicking hepatobiliary diseases such as primary sclerosing cholangitis (PSC), secondary sclerosing cholangitis (SSC), and cholangiocarcinoma. IgG4-SC has an excellent prognosis when promptly diagnosed and treated with steroids. Literature search strategy: The authors searched PubMed and Google Scholar, for articles with the search terms "autoimmune cholangiopathy" and "IgG4 cholangiopathy."

Imaging of Biliary Tree Abnormalities

Pathologic conditions of the biliary system, although common, can be difficult to diagnose clinically. Challenges in biliary imaging include anatomic variants and the dynamic nature of the biliary tract, which can change with age and intervention, blurring the boundaries of normal and abnormal. Choledochal cysts can have numerous appearances and are important to diagnose given the risk of cholangiocarcinoma potentially requiring surgical resection. Choledocholithiasis, the most common cause of biliary dilatation, can be difficult to detect at US and CT, with MRI having the highest sensitivity. However, knowledge of the imaging pitfalls of MRI and MR cholangiopancreatography is crucial to avoid misinterpretation. Newer concepts in biliary tract malignancy include intraductal papillary biliary neoplasms that may develop into cholangiocarcinoma. New paradigms in the classification of cholangiocarcinoma correspond to the wide range of imaging appearances of the disease and have implications for prognosis. Accurately staging cholangiocarcinoma is imperative, given expanding curative options including transplant and more aggressive surgical options. Infections of the biliary tree include acute cholangitis or recurrent pyogenic cholangitis, characterized by obstruction, strictures, and central biliary dilatation. Inflammatory conditions include primary sclerosing cholangitis, which features strictures and fibrosis but can be difficult to differentiate from secondary causes of sclerosing cholangitis, including more recently described entities such as immunoglobulin G4-related sclerosing cholangitis and COVID-19 secondary sclerosing cholangitis. The authors describe a wide variety of benign and malignant biliary tract abnormalities, highlight differentiating features of the cholangitides, provide an approach to interpretation based on the pattern of imaging findings, and discuss pearls and pitfalls of imaging to facilitate accurate diagnosis. ©RSNA, 2024 Supplemental material is available for this article.

Renal Manifestations of IgG4-Related Disease: A Concise Review

IgG4-related disease (IgG4-RD) is an immune-mediated disorder marked by fibro-inflammatory masses that can infiltrate multiple organ systems. Due to its relatively recent discovery and limited understanding of its pathophysiology, IgG4-related disease may be difficult to recognize and is consequently potentially underdiagnosed. Renal involvement is becoming regarded as one of the key features of this disease. To date, the most well-recognized renal complication of IgG4-related disease is tubulointerstitial nephritis, but membranous glomerulonephritis, renal masses, and retroperitoneal fibrosis have also been reported. This concise review has two objectives. First, it will briefly encapsulate the history, epidemiology, and presentation of IgG4-related disease. Second, it will examine the reported renal manifestations of IgG4-related disease, exploring the relevant histology, imaging, clinical features, and treatment considerations. This synthesis will be highly relevant for nephrologists, rheumatologists, general internists, and renal pathologists to raise awareness and help improve early recognition of IgG4-related kidney disease (IgG4-RKD).

An atypical case of isolated immunoglobulin G4-related sclerosing cholangitis with a cholangiogram resembling primary sclerosing cholangitis

An asymptomatic 77-year-old man with intrahepatic bile duct dilation was referred to our hospital. Cholangiography revealed alternations between strictures and dilated segments from the right and left hepatic ducts to the lower bile ducts, with findings of a pruned tree, beaded, shaggy appearance, and diverticulum-like outpouching. Histopathology revealed abundant immunoglobulin G4 (IgG4)-positive plasma cells (> 10 per high-power field) with an IgG4/IgG-positive cell ratio of 40-50%. After 2 weeks of steroid therapy, the cholangiography markedly improved. Because the cholangiographic findings resembled those of primary sclerosing cholangitis, steroid therapy proved useful in differentiating IgG4-related sclerosing cholangitis from primary sclerosing cholangitis.

Recombinant adeno-associated virus 8-mediated inhibition of microRNA let-7a ameliorates sclerosing cholangitis in a clinically relevant mouse model

BACKGROUND

Primary sclerosing cholangitis (PSC) is characterized by chronic inflammation and it predisposes to cholangiocarcinoma due to lack of effective treatment options. Recombinant adeno-associated virus (rAAV) provides a promising platform for gene therapy on such kinds of diseases. A microRNA (miRNA) let-7a has been reported to be associated with the progress of PSC but the potential therapeutic implication of inhibition of let-7a on PSC has not been evaluated.

AIM

To investigate the therapeutic effects of inhibition of a miRNA let-7a transferred by recombinant adeno-associated virus 8 (rAAV8) on a xenobiotic-induced mouse model of sclerosing cholangitis.

METHODS

A xenobiotic-induced mouse model of sclerosing cholangitis was induced by 0.1% 3,5-Diethoxycarbonyl-1,4-Dihydrocollidine (DDC) feeding for 2 wk or 6 wk. A single dose of rAAV8-mediated anti-let-7a-5p sponges or scramble control was injected in vivo into mice onset of DDC feeding. Upon sacrifice, the liver and the serum were collected from each mouse. The hepatobiliary injuries, hepatic inflammation and fibrosis were evaluated. The targets of let-7a-5p and downstream molecule NF-κB were detected using Western blot.

RESULTS

rAAV8-mediated anti-let-7a-5p sponges can depress the expression of let-7a-5p in mice after DDC feeding for 2 wk or 6 wk. The reduced expression of let-7a-5p can alleviate hepato-biliary injuries indicated by serum markers, and prevent the proliferation of cholangiocytes and biliary fibrosis. Furthermore, inhibition of let-7a mediated by rAAV8 can increase the expression of potential target molecules such as suppressor of cytokine signaling 1 and Dectin1, which consequently inhibit of NF-κB-mediated hepatic inflammation.

CONCLUSION

Our study demonstrates that a rAAV8 vector designed for liver-specific inhibition of let-7a-5p can potently ameliorate symptoms in a xenobiotic-induced mouse model of sclerosing cholangitis, which provides a possible clinical translation of PSC of human.

Significant CA 19-9 elevation in IgG4-related autoimmune pancreatitis - A diagnostic dilemma

IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory disorder characterized by dense infiltration of IgG4-positive plasma cells in the affected tissue along with characteristic storiform fibrosis that can lead to the development of tumefactive lesions in any organ. CA19-9 is a marker for pancreato-biliary malignancy, however mild to moderate elevation of CA 19-9 can also be observed in IgG4-RD autoimmune pancreatitis (AIP) and sclerosing cholangitis (IgG4-SC). Therefore, it becomes difficult to differentiate between these entities. We describe the case of a 65-year-old male with history of IgG4-RD, presenting with jaundice and abdominal pain. He was found to have a pancreatic mass with significantly elevated IgG4 162 (2-96 mg/dL and CA19-9 levels 2830 (0-35 U/ml). Patient underwent ERCP and biopsy, which ruled out pancreatic cancer and cholangiocarcinoma. He was diagnosed with IgG4-RD autoimmune pancreatitis (AIP) and sclerosing cholangitis. Treatment with steroids and rituximab resulted in significant improvement in the bilirubin and a dramatic decrease in CA19-9 levels.

IgG4-related digestive diseases: diagnosis and treatment

IgG4-related digestive diseases encompass a group of chronic inflammatory disorders characterized by autoimmune reactions and fibrosis affecting multiple digestive organs. These diseases are identified by elevated serum levels of IgG4 and the presence of IgG4-positive plasma cell infiltration in the affected sites, along with storiform fibrosis, obliterative phlebitis, and eosinophilic infiltration. Although extensive research has been conducted, a comprehensive understanding of these conditions remains elusive. Current clinical diagnosis often relies on the application of integrated diagnostic criteria for IgG4-related diseases, combined with specific organ involvement criteria. Distinguishing them from malignancies poses considerable challenges. Moreover, further investigations are required to elucidate the underlying pathogenic mechanisms and explore potential therapeutic interventions. This review provides a systematic classification of IgG4-related digestive diseases while discussing their diagnostic strategies, clinical presentations, and treatment modalities. The comprehensive insights shared herein aim to guide clinicians in their practice and contribute to the advancement of knowledge in this field.

Post-COVID-19 cholangiopathy: Systematic review

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has had a profound impact on global health, primarily characterized by severe respiratory illness. However, emerging evidence suggests that COVID-19 can also lead to secondary sclerosing cholangitis (SC), referred to as post-COVID-19 cholangiopathy.

AIM

To synthesize currently reported cases to assess the current state of knowledge on post-COVID-19 cholangiopathy.

METHODS

Medical Subject Headings and Health Sciences Descriptors were used to retrieve relevant studies, which were combined using Boolean operators. Searches were conducted on electronic databases including Scopus, Web of Science, and MEDLINE (PubMed). Studies published in English, Spanish, or Portuguese were included, with no restrictions on the publication date. Additionally, the reference lists of retrieved studies were manually searched. Simple descriptive analyses were used to summarize the results. Then the data were extracted and assessed based on Reference Citation Analysis (https://www.referencecitationanalysis.com/).

RESULTS

The initial search yielded a total of 192 articles. After screening, 85 articles were excluded due to duplication, leaving 107 articles for further review. Of these, 63 full-length articles met the inclusion criteria and were included in the analyses. Most of the patients were male and exhibited elevated liver function tests (93.8%). Magnetic resonance imaging revealed duct thickening with contrast enhancement (47.7%), as well as beading of the intrahepatic ducts (45.7%) with peribiliary contrast enhancement on diffusion (28.7%). Liver biopsy results confirmed SC in most cases (74.4%). Sixteen patients underwent liver transplantation, with three experiencing successful outcomes.

CONCLUSION

Post-COVID-19 cholangiopathy is a serious condition that is expected to become increasingly concerning in the coming years, particularly considering long COVID syndromes. Although liver transplantation has been proposed as a potential treatment option, more research is necessary to establish its efficacy and explore other potential treatments.

Bile Duct Lithiasis Mimicking a Perihilar Cholangiocarcinoma-An Endless Dilemma: A Case Report

Hilar bile duct strictures are mostly caused by malignant lesions. The morphological appearance of perihilar cholangiocarcinomas in various imaging modalities have other malignant and even benign mimics, which pose challenges to an accurate diagnosis and treatment and drive to futile surgery. Herein, we present the case of a 50-year-old woman admitted with jaundice and abdominal pain, elevated bilirubin level, liver function tests and carbohydrate antigen 19-9 level. Magnetic resonance cholangio-pancreatography (MR-CP) and the computed tomography with contrast enhancement revealed a suspected extrahepatic cholangiocarcinoma of the common bile duct. Further spontaneous resolution of the scenario, confirmed by diagnostic assessment, changed the clinical hypothesis in favor of a non-oncological disease. Indeed, the multidisciplinary evaluation supported a diagnosis of transient cholangitis secondary to non-evident intrahepatic lithiasis rather than cholangiocarcinoma. After a 26-month follow-up, the patient was asymptomatic with normal tumor markers and laboratory data. Consecutive MR-CPs showed no suspicion of malignancy. This case report underlines the need for an accurate preoperative assessment in patients with suspected cholangiocarcinoma.

Ulcerative colitis complicated by primary sclerosing cholangitis and autoimmune hepatitis overlap syndrome: a case report and literature review

Primary sclerosing cholangitis (PSC), autoimmune hepatitis (AIH), and ulcerative colitis (UC) are immune diseases of the digestive system. Some patients develop overlap syndrome, the presentation of two or more of the clinical, biochemical, immunological, and histological features of these conditions simultaneously or sequentially. The incidence of UC in PSC-AIH overlap syndrome is as high as 50%. In contrast, PSC-AIH overlap syndrome is rare in UC patients. However, because it has a low prevalence and has been studied in less detail, PSC is often misdiagnosed as primary biliary cholangitis (PBC) in its early stage. Herein, we reported a case of a 38-year-old male patient who presented to a clinician in 2014 with irregular bowel habits. A colonoscopy suggested UC. In 2016, the patient was found to have abnormal liver function and was diagnosed with PBC by pathology. He was treated with ursodeoxycholic acid (UDCA) but this had no effect on his liver function. Additional liver biopsies in 2018 indicated PBC-AIH overlap syndrome. The patient refused hormone therapy for personal reasons. Following UDCA monotherapy, his liver function remained abnormal. The patient was reexamined after repeated abnormal liver function tests and bowel symptoms. Systematic laboratory testing, imaging diagnosis, colonoscopy, liver biopsy, and various pathological examinations conducted in 2021 were used to diagnose the patient with PSC-AIH-UC overlap syndrome. He was treated with various drugs, including UDCA, methylprednisolone, mycophenolate mofetil, and mesalazine. His liver function improved significantly after treatment and follow-up is ongoing. Our case report highlights the need to raise awareness about rare and difficult-to-diagnose clinical disorders.

Morphological aspects of small-duct cholangiopathies: A minireview

The biliary system consists of intrahepatic and extrahepatic bile ducts lined by biliary epithelial cells (cholangiocytes). Bile ducts and cholangiocytes are affected by a variety of disorders called cholangiopathies, which differ in aetiology, pathogenesis, and morphology. Classification of cholangiopathies is complex and reflects pathogenic mechanisms (immune-mediated, genetic, drug- and toxin-induced, ischaemic, infectious, neoplastic), predominant morphological patterns of biliary injury (suppurative and non-suppurative cholangitis, cholangiopathy), and specific segments of the biliary tree affected by the disease process. While the involvement of large extrahepatic and intrahepatic bile ducts is typically visualised using radiology imaging, histopathological examination of liver tissue obtained by percutaneous liver biopsy still plays an important role in the diagnosis of cholangiopathies affecting the small intrahepatic bile ducts. To increase the diagnostic yield of a liver biopsy and determine the optimal therapeutic approach, the referring clinician is tasked with interpreting the results of histopathological examination. This requires knowledge and understanding of basic morphological patterns of hepatobiliary injury and an ability to correlate microscopic findings with results obtained by imaging and laboratory methods. This minireview describes the morphological aspects of small-duct cholangiopathies pertaining to the diagnostic process.

Secondary sclerosing cholangitis and IgG4-sclerosing cholangitis - A review of cholangiographic and ultrasound imaging

Sclerosing cholangitis (SC) represents a spectrum of chronic progressive cholestatic diseases of the intrahepatic and/or extrahepatic biliary system characterized by patchy inflammation, fibrosis, and stricturing. Primary and secondary SC must be distinguished given the different treatment modalities, risks of malignancy, and progression to portal hypertension, cirrhosis, and hepatic failure. This review focuses on secondary SC and the pathogenic mechanisms, risk factors, clinical presentation, and novel imaging modalities that help to distinguish between these conditions. We explore the detailed use of cholangiography and ultrasound imaging techniques.

The role of ion channels in immune-related diseases

Ion channel is an integral membrane protein that allows the permeation of charge ions across hydrophobic phospholipid membranes, including plasma membranes and organelle membranes (such as mitochondria, endoplasmic reticulum and vacuoles), which are widely distributed in various cells and tissues, such as cardiomyocytes, smooth muscle cells, and nerve cells. Ion channels establish membrane potential by regulating ion concentration and membrane potential. Membrane potential plays an important role in cells. Studies have shown that ion channels play a role in a number of immune-related diseases caused by functional defects in ion channels on immune or non-immune cells in major human organs, usually affecting specific organs or multiple organs. The present review discusses the relationship between ion channels and immune diseases in major organs of the human body.

Bibliometric analysis of IgG4-related disease research from 2003 to 2022 based on Web of Science Core Collection Databases

This study aimed to perform a bibliometric analysis of the IgG4-related disease (IgG4-RD) research field over the past 20 years to explore its research hotspots and trends. The literature of IgG4-RD published in the Web of Science Core Collection databases was reviewed from January 1, 2003, to April 30, 2022. A bibliometric analysis was carried out using CiteSpace software to evaluate and visualize the evolving dynamics and hotspots in the field of IgG4-RD. A total of 3174 IgG4-RD articles were reviewed. Since 2011, there has been a rapid increase in published literature. Japan is the highest yielding country and Kanazawa University the highest yielding institution. The USA has the highest centrality (0.34) and plays a critical role in cooperation and communication of IgG4-RD research. Nine highly connected clusters of IgG4-RD were observed by keyword analysis. Research hotspots included IgG4-RD involved organs and differentiation from Rosai-Dorfman disease and primary sclerosing cholangitis. Further research topics include pathogenesis, relapse, and malignancy. As a cross-discipline systemic disease, IgG4-RD requires attention by clinicians in multiple fields. This bibliometric analysis can help researchers grasp trends and provide new perspectives for future research on IgG4-RD.

[Differential diagnosis of IgG4-related disease]

IgG4-related disease is a chronic autoimmune fibro-inflammatory disease characterized by the presence of lymphoplasmacytic infiltrate, storiform fibrosis, obliterating phlebitis, increased number of IgG4+ cells in tissue, and, in most cases, an elevated serum IgG4 level. This disease often affects the pancreas, salivary glands and lymph nodes, but can involve almost any tissue. Its etiology is still unclear, the central role in the pathogenesis belongs to B-lymphocytes, T2-helpers, interleukins 1-β, 4, 5, 10, 13 and tumor growth factor 1-β. The ambiguous clinical picture and frequent simultaneous involvement of several organs make it difficult to diagnose, so biopsy plays a leading role in making a diagnosis. The characteristic microscopic picture, the presence of certain populations of lymphocytes are key criteria in establishing the correct diagnosis.

Hepatobiliary Impairments in Patients with Inflammatory Bowel Diseases: The Current Approach

Inflammatory bowel disease (IBD) refers to chronic conditions with a low mortality but high disability. The multisystemic nature of these diseases can explain the appearance of some extraintestinal manifestations, including liver damage. Abnormal liver biochemical tests can be identified in approximately one third of patients with IBD and chronic liver disease in 5% of them. Among the liver diseases associated with IBD are primary sclerosing cholangitis, cholelithiasis, fatty liver disease, hepatic amyloidosis, granulomatous hepatitis, drug-induced liver injury, venous thromboembolism, primary biliary cholangitis, IgG4-related cholangiopathy, autoimmune hepatitis, liver abscesses or the reactivation of viral hepatitis. The most common disease is primary sclerosing cholangitis, a condition diagnosed especially in patients with ulcerative colitis. The progress registered in recent years in the therapeutic management of IBD has not eliminated the risk of drug-induced liver disease. Additionally, the immunosuppression encountered in these patients increases the risk of opportunistic infections, including the reactivation of viral hepatitis. Currently, one of the concerns consists of establishing an efficiency and safety profile of the use of direct-acting antiviral agents (DAA) among patients with hepatitis C and IBD. Early diagnosis and optimal treatment of liver complications can improve the prognoses of these patients.

A Case of Hepatic Immunoglobulin G4-Related Disease Presenting as an Inflammatory Pseudotumor and Sclerosing Cholangitis

An inflammatory pseudotumor is a benign disease characterized by tumor-like lesions consisting of inflammatory cells including plasma cells and fibrous tissue. Recently, some inflammatory pseudotumor cases proved to be a form of Immunoglobulin G4-related disease (IgG4-RD). This novel clinical entity, recognized as a fibroinflammatory condition, is characterized by lymphoplasmacytic infiltration with a predominance of IgG4-positive plasma cells, storiform fibrosis, and often elevated serum IgG4 concentrations. We report a case of IgG4-RD in the form of an inflammatory pseudotumor in the liver with combined sclerosing cholangitis. We recommend that for diagnosing IgG4-RD accurately, it is important to obtain adequate tissue samples and follow-up the lesion in clinical practice.

A novel serum metabolomic panel distinguishes IgG4-related sclerosing cholangitis from primary sclerosing cholangitis

BACKGROUND & AIMS

Primary sclerosing cholangitis (PSC) and IgG4-related sclerosing cholangitis (IgG4-SC) are chronic fibro-inflammatory immune-mediated hepatobiliary conditions that are challenging to distinguish in a clinical setting. Accurate non-invasive biomarkers for discriminating PSC and IgG4-SC are important to ensure a correct diagnosis, prompt therapy and adequate cancer surveillance.

METHODS

We performed nuclear magnetic resonance (NMR)-based metabolomic profiling using serum samples collected prospectively from patients with PSC (n = 100), IgG4-SC (n = 23) and healthy controls (HC; n = 16).

RESULTS

Multivariate analysis of the serum metabolome discriminated PSC from IgG4-SC with greater accuracy (AUC 0.95 [95%CI 0.90-0.98]) than IgG4 titre (AUC 0.87 [95%CI 0.79-0.94]). When inflammatory bowel disease (IBD) was excluded as a comorbid condition (IgG4-SC n = 20, PSC n = 22), the diagnostic AUC increased to 1.0, suggesting that the metabolome differences identified are not a result of the increased prevalence of IBD in PSC relative to IgG4-SC patients. Serum lactate (p < .0001), glucose (p < .01) and glutamine (p < .01) metabolites were increased in IgG4-related disease (IgG4-RD) and IgG4-SC individuals compared to PSC, whereas mobile choline (p < .05), 3-hydroxybutyric acid (p < .01) and -CH₃ lipoprotein resonances (p < .01) were decreased.

CONCLUSIONS

Taken together, serum metabolomic profiling has the potential to be incorporated as a diagnostic criterion, independent of IgG4 titre, to improve the diagnosis of IgG4-RD and help distinguish IgG4-SC from PSC.

Altered faecal microbiome and metabolome in IgG4-related sclerosing cholangitis and primary sclerosing cholangitis

OBJECTIVE

Multiple clinical similarities exist between IgG4-related sclerosing cholangitis (IgG4-SC) and primary sclerosing cholangitis (PSC), and while gut dysbiosis has been extensively studied in PSC, the role of the gut microbiota in IgG4-SC remains unknown. Herein, we aimed to evaluate alterations of the gut microbiome and metabolome in IgG4-SC and PSC.

DESIGN

We performed 16S rRNA gene amplicon sequencing of faecal samples from 135 subjects with IgG4-SC (n=34), PSC (n=37) and healthy controls (n=64). A subset of the samples (31 IgG4-SC, 37 PSC and 45 controls) also underwent untargeted metabolomic profiling.

RESULTS

Compared with controls, reduced alpha-diversity and shifted microbial community were observed in IgG4-SC and PSC. These changes were accompanied by differences in stool metabolomes. Importantly, despite some common variations in the microbiota composition and metabolic activity, integrative analyses identified distinct host-microbe associations in IgG4-SC and PSC. The disease-associated genera and metabolites tended to associate with the transaminases in IgG4-SC. Notable depletion of Blautia and elevated succinic acid may underlie hepatic inflammation in IgG4-SC. In comparison, potential links between the microbial or metabolic signatures and cholestatic parameters were detected in PSC. Particularly, concordant decrease of Eubacterium and microbiota-derived metabolites, including secondary bile acids, implicated novel host-microbial metabolic pathways involving cholestasis of PSC. Interestingly, the predictive models based on metabolites were more effective in discriminating disease status than those based on microbes.

CONCLUSIONS

Our data reveal that IgG4-SC and PSC possess divergent host-microbe interplays that may be involved in disease pathogenesis. These data emphasise the uniqueness of IgG4-SC.

IgG4-Related Sclerosing Cholangitis: Rarely Diagnosed, but not a Rare Disease

IgG4-related sclerosing cholangitis, a biliary manifestation of an IgG4-related disease, belongs to the spectrum of sclerosing cholangiopathies which result in biliary stenosis. It presents with signs of cholestasis and during differential diagnosis it should be distinguished from cholangiocarcinoma or from other forms of sclerosing cholangitis (primary and secondary sclerosing cholangitis). Despite increasing information and recently established diagnostic criteria, IgG4-related sclerosing cholangitis remains underdiagnosed in routine clinical practice. The diagnosis is based on a combination of the clinical picture, laboratory parameters, histological findings, and a cholangiogram. Increased serum IgG4 levels are nonspecific but are indeed a part of the diagnostic criteria proposed by the Japan Biliary Association and the HISORt criteria for IgG4-SC. High serum IgG4 retains clinical utility depending on the magnitude of elevation. Approximately 90% of patients have concomitant autoimmune pancreatitis, while 10% present with isolated biliary involvement only. About 26% of patients have other organ involvement, such as IgG4-related dacryoadenitis/sialadenitis, IgG4-related retroperitoneal fibrosis, or IgG4-related renal lesions. A full-blown histological finding characterized by IgG4-enriched lymphoplasmacytic infiltrates, obliterative phlebitis, and storiform fibrosis is difficult to capture in practice because of its subepithelial localization. However, the histological yield is increased by immunohistochemistry, with evidence of IgG4-positive plasma cells. Based on a cholangiogram, IgG-4 related sclerosing cholangitis is classified into four subtypes according to the localization of stenoses. The first-line treatment is corticosteroids. The aim of the initial treatment is to induce clinical and laboratory remission and cholangiogram normalization. Even though 30% of patients have a recurrent course, in the literature data, there is no consensus on chronic immunosuppressive maintenance therapy. The disease has a good prognosis when diagnosed early.

Primary sclerosing cholangitis with moderately elevated serum-IgG4 - characterization and outcome of a distinct variant phenotype

BACKGROUND AND AIMS

Immunoglobulin G4-associated cholangitis (IAC) is characterized by distinctly elevated immunoglobulin G4 in serum (sIgG4) and responds well to corticosteroid therapy. Primary Sclerosing Cholangitis (PSC) is a progressive liver disease without causal treatment options usually not responding to immunosuppression. Increased serum levels of sIgG4 in patients with PSC, that do not meet criteria of IAC, have been reported in 10%-25%. Therefore, we aimed to characterize this subgroup of patients in a retrospective, multicenter study.

METHODS

sIgG4 values of 289 patients with PSC from three German university hospitals were analysed. Patients with elevated sIgG4 levels were identified and further characterized by clinical and biochemical parameters and by cholangiographic presentation. Clinical endpoints, death and liver transplantation were compared between groups. Parameters associated with outcome were identified with Cox regression analysis.

RESULTS

14.5% of patients with PSC showed increased sIgG4 levels (PSC-IgG4), presented with significantly higher (P < .02) albumin, aspartate-aminotransferase, bilirubin and alkaline phosphatase and had a significant lower prevalence of a concomitant autoimmune hepatitis (P = .025). Cholangiogram obtained via ERC showed extrahepatic dominant strictures more often in the PSC-IgG4 subgroup (P = .047). The disease severity models Amsterdam-Oxford-Score (P = .018) and Mayo-Risk-Score (P = .025) predicted lower survival rates for the PSC-IgG4 subgroup. Transplant-free survival after first diagnosis of PSC was shorter in patients with elevated sIgG4 (11.6 vs 15.1 years, P = .001).

CONCLUSION

Patients with PSC and elevated sIgG4 should be considered as a distinct subgroup, characterized by different clinical and cholangiographical features and are associated with an inferior outcome.

Clinical Perspectives on IgG4-Related Disease and Its Classification

Immunoglobulin G4-related disease (IgG4-RD) is a systemic immune-mediated fibroinflammatory disease. Since its discovery nearly two decades ago, our understanding of its pathophysiology and clinical manifestations has grown substantially. Early diagnosis and treatment of this elusive disease can prevent substantial organ damage from end-stage fibrosis, emphasizing the need for prompt recognition and accurate characterization of IgG4-RD. The classification criteria endorsed by the American College of Rheumatology and the European Alliance of Associations for Rheumatology in 2019 provide a framework for establishing the diagnosis in the clinical setting. This process involves recognizing the typical manifestations of the disease and incorporating clinical, radiological, serological, and histopathological information as well as excluding disease mimickers. Glucocorticoids and rituximab are effective at inducing remission in IgG4-RD in most patients, but the optimal approach to long-term management of IgG4-RD remains an area of active clinical research. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

The Role of B Cells in Adult and Paediatric Liver Injury

B lymphocytes are multitasking cells that direct the immune response by producing pro- or anti-inflammatory cytokines, by presenting processed antigen for T cell activation and co-stimulation, and by turning into antibody-secreting cells. These functions are important to control infection in the liver but can also exacerbate tissue damage and fibrosis as part of persistent inflammation that can lead to end stage disease requiring a transplant. In transplantation, immunosuppression increases the incidence of lymphoma and often this is of B cell origin. In this review we bring together information on liver B cell biology from different liver diseases, including alcohol-related and metabolic fatty liver disease, autoimmune hepatitis, primary biliary and primary sclerosing cholangitis, viral hepatitis and, in infants, biliary atresia. We also discuss the impact of B cell depletion therapy in the liver setting. Taken together, our analysis shows that B cells are important in the pathogenesis of liver diseases and that further research is necessary to fully characterise the human liver B cell compartment.

Classification and Diagnostic Criteria for IgG4-Related Sclerosing Cholangitis

IgG4-related sclerosing cholangitis (IgG4-SC) can be classified into four types based on cholangiographic findings and regions of biliary stricture. This cholangiographic classification is useful to differentiate IgG4-SC from mimickers including cholangiocarcinoma, primary sclerosing cholangitis, and pancreatic cancer. Autoimmune pancreatitis (AIP) is a valuable clue for the diagnosis of IgG4-SC because the two are frequently found in association with each other. Two sets of diagnostic criteria for IgG4-SC have been proposed. In Japan, the clinical diagnostic criteria 2020 were recently developed. These clinical diagnostic criteria include narrowing of the intrahepatic and/or extrahepatic bile duct, thickening of the bile duct wall, serological findings, pathological findings, other organ involvement, and effectiveness of steroid therapy. When these criteria are applied, IgG4-SC is initially classified as associated or not associated with AIP, and cholangiographic classification is used for differential diagnosis. In most instances, IgG4-SC can be diagnosed on the basis of clinical diagnostic criteria. However, it is challenging to diagnose isolated IgG4-SC or IgG4-SC not associated with AIP. Here, we review the classification and diagnostic criteria for IgG4-SC, specifically focusing on the clinical diagnostic criteria 2020 and a large IgG4-SC case series from a nationwide survey in Japan.

Recurrent Primary Sclerosing Cholangitis: Current Understanding, Management, and Future Directions

Patients with primary sclerosing cholangitis (PSC) constitute 5 to 15% of patients listed for liver transplantation worldwide. Although post-transplant outcomes are favorable, recurrent PSC (rPSC) occurs in an important subset of patients, with higher prevalence rates reported with increasing time from transplant. Given its association with poor graft outcomes and risk of retransplant, effort has been made to understand rPSC, its pathophysiology, and risk factors. This review covers these facets of rPSC and focuses on implicated risk factors including pretransplant recipient characteristics, inflammatory bowel-disease-related factors, and donor-specific and transplant-specific factors. Confirming a diagnosis of rPSC requires thoughtful consideration of alternative etiologies so as to ensure confidence in diagnosis, management, subsequent risk assessment, and counseling for patients. Unfortunately, no cure exists for rPSC; however, future large-scale efforts are underway to better characterize the natural history of rPSC and its associated risk factors with hopes of identifying potential key targets for novel therapies.

[Novel Insights of Primary Sclerosing Cholangitis and Primary Biliary Cholangitis]

Primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) are immune-mediated chronic liver diseases. PSC is a rare disorder characterized by multi-focal bile duct strictures and progressive liver diseases that ultimately results in the need for liver transplantation in most patients. Imaging studies, such as MRCP, have an essential role in the diagnosis of most cases of PSC. PSC is usually accompanied by inflammatory bowel disease, and there is a high risk of cholangiocarcinoma and colorectal cancer in PSC. No medical therapies have been proven to delay the progression of PSC. Endoscopic intervention for tissue diagnosis or biliary drainage is frequently required in cases of PSC with a dominant stricture, acute cholangitis, or clinically suspected cholangiocarcinoma. PBC is a chronic inflammatory autoimmune cholestatic liver disease, which, when untreated, will culminate in end-stage biliary cirrhosis requiring liver transplantation. A diagnosis is usually based on the presence of serum liver tests indicative of cholestatic hepatitis in association with circulating antimitochondrial antibodies. Patient presentation and course can be diverse in PBC, and risk stratification is important for ensuring that all patients receive a personalized approach to their care. Medical therapy using ursodeoxycholic acid or obeticholic acid has an important role in reducing the progression to end-stage liver disease in PBC.

Isolated Type Immunoglobulin G4 Sclerosing Cholangitis: The Misdiagnosed Cholangiocarcinoma

Immunoglobulin G4 sclerosing cholangitis (IgG4-SC), firstly described in 2004, is the biliary manifestation of a recently described multisystem immune-mediated disease known as IgG4-related disease. IgG4-SC is a unique and rare type of cholangitis of unknown etiology and its precise prevalence rate is still unclear. It is characterized by bile duct wall thickening and high levels of systemic serum IgG4 plasma cells. Differential diagnoses for IgG4-SC include benign (primary sclerosing cholangitis) as well as malignant (extra-hepatic cholangiocarcinoma) diseases. Discrimination between these entities is very important, due to the fact that they have different biological behaviors and different therapeutic strategies. The rare IgG4-SC subgroup with its puzzling manifestations carries a hefty diagnostic challenge for the treating physicians, and inaccurate diagnosis can lead to unnecessary morbid surgical procedures. With the paucity and relative weakness of available data in the current literature, one needs to carefully review all available parameters. A low threshold of suspicion is required to try and prevent missing IgG4-SC. IgG4-SC is highly responsive to steroid treatment, especially during the early inflammatory phase, while delay in management could lead to fibrosis and organ dysfunction. On the other hand, cholangiocarcinoma is treated by means of surgery and/or chemotherapeutic agents.

Usefulness of ultrasonography to assess the response to steroidal therapy for the rare case of type 2b immunoglobulin G4-related sclerosing cholangitis without pancreatitis: A case report

BACKGROUND

A type 2b immunoglobulin G4 (IgG4)-related sclerosing cholangitis (SC) without autoimmune pancreatitis is a rare condition with IgG4-SC. While the variety of the imaging modalities have tested its usefulness in diagnosing the IgG4-SC, however, the usage of ultrasonography for the assessment of the response to steroidal therapy on the changes of bile duct wall thickness have not been reported in the condition. Therefore, the information of our recent case and reported cases have been summarized.

CASE SUMMARY

We report the case of an 82-year-old Japanese man diagnosed with isolated IgG4-related SC based on the increase of serum IgG4, narrowing of the bile duct, its wall thickness, no complication of autoimmune pancreatitis, and IgG4 positive inflammatory cell infiltration to the wall with the fibrotic changes. The cholangiogram revealed type 2b according to the classification. Corticosteroid treatment showed a favorable effect, with the smooth decrease in serum IgG4 and the improvement of the bile duct wall thickness.

CONCLUSION

As isolated type 2b, IgG4-SC is rare, the images, histological findings, and clinical course of our case will be helpful for physicians to diagnose and treat the new cases appropriately.

Role of Peroral Cholangioscopy in the Diagnosis of Primary Sclerosing Cholangitis

Primary sclerosing cholangitis (PSC) is characterized by idiopathic biliary stricture followed by progressive cholestasis and fibrosis. When diagnosing PSC, its differentiation from other types of sclerosing cholangitis and cholangiocarcinoma is necessary. The cholangioscopic findings of PSC have not been investigated sufficiently. PSC and IgG4-related sclerosing cholangitis are difficult to distinguish by peroral cholangioscopy (POCS), but POCS is useful for excluding cholangiocarcinoma. POCS findings vary according to the condition and stage of disease. In the active phase, findings such as mucosal erythema, ulceration, fibrinous white exudate, and an irregular surface are observed and may reflect strong inflammation in the biliary epithelium. On the other hand, findings such as scarring, pseudodiverticula, and bile duct stenosis appear in the chronic phase and may reflect fibrosis and stenosis resulting from repeated inflammation. Observation of inside the bile duct by POCS might confirm the current PSC activity. Because POCS offers not only information regarding the diagnosis of PSC and PSC-associated cholangiocarcinoma but also the current statuses of biliary inflammation and stenosis, POCS could significantly contribute to the diagnosis and treatment of PSC once the characteristic findings of PSC are confirmed by future studies.

Colangitis esclerosante primaria. Una revisión narrativa

La colangitis esclerosante primaria (CEP) es una patología hepática crónica y rara que se caracterizapor la inflamación y fibrosis de los conductos biliares, cuya evolución puede llevar a la cirrosis, hipertensión portal y enfermedad hepática en etapa terminal. Su etiología es desconocida, pero se ha relacionado con factores genéticos y autoinflamatorios. Además, tiene una relación muy estrecha con la enfermedad inflamatoria intestinal (EII). Su presentación clínica es muy inespecífica, sus principales síntomas son el prurito y la fatiga. La prueba estándar para su diagnóstico es la colangiopancreatografía por resonancia magnética (CPRM), donde se observa un aspecto anular ocasionado por estenosis multifocales cortas con segmentos alternos normales o dilatados. Actualmente, no existe ningún tratamiento farmacológico que logre prolongar la supervivencia sin un trasplante de hígado en la CEP. Sólo se puede hacer tratamiento sintomático, especialmente del prurito. El único manejo curativo con el que se cuenta hoy en día es el trasplante hepático, aunque existe un riesgo de recurrencia de la enfermedad. Es muy importante la vigilancia de los trastornos inflamatorios intestinales, la malignidad y la enfermedad metabólica ósea en estos pacientes. Se ha visto que algunos factores, como el diagnóstico temprano, son de buen pronóstico para la enfermedad.

Peribiliary glands: development, dysfunction, related conditions and imaging findings

Peribiliary glands are minute structures that are distributed along the intrahepatic large bile ducts, extrahepatic bile duct, and cystic duct. These glands regulate many physiological functions, such as enzyme secretion. Pancreatic exocrine tissues and enzymes are often observed in peribiliary glands; thus, peribiliary glands are involved in enzyme secretion. As such, these glands can be affected by conditions such as IgG4-related sclerosing cholangitis based on commonalities with their pancreatic counterparts. Cystic changes in peribiliary glands can occur de novo, as part of a congenital syndrome, or secondary to insults such as alcoholic cirrhosis. Biliary tree stem/progenitor cells have recently been identified in peribiliary glands. These cells are involved in turnover and regeneration of biliary epithelia as well as in sclerosing reactions in some pathological conditions, such as primary sclerosing cholangitis and hepatolithiasis. Notably, hepatolithiasis is involved in mucin secretion by the peribiliary glands. Additionally, these cells are associated with the manifestation of several neoplasms, including intraductal papillary neoplasm, cystic micropapillary neoplasm, and cholangiocarcinoma. Normal peribiliary glands themselves are particularly small structures that cannot be recognized using any available imaging modalities; however, these glands are closely associated with several diseases, as mentioned above, which have typical imaging features. Therefore, knowledge of the basic pathophysiology of peribiliary glands is helpful for understanding biliary diseases associated with the peribiliary glands.