IgG4-related sclerosing disease: autoimmune pancreatitis and extrapancreatic manifestations

Predominantly multiple focal non-cystic renal lesions: an imaging approach

Multiple non-cystic renal lesions are occasionally discovered during imaging for various reasons and poses a diagnostic challenge to the practicing radiologist. These lesions may appear as a primary or dominant imaging finding or may be an additional abnormality in the setting of multiorgan involvement. Awareness of the imaging appearance of the various entities presenting as renal lesions integrated with associated extrarenal imaging findings along with clinical information is crucial for a proper diagnostic approach and patient work-up. This review summarizes the most relevant causes of infectious, inflammatory, vascular, and neoplastic disorders presenting as predominantly multiple focal non-cystic lesions.

Radiology domain in the diagnosis of IgG4-RD according to the 2019 American College of Rheumatology and European League Against Rheumatism classification

OBJECTIVES

To evaluate the performance of radiology-related inclusion criteria of the 2019 ACR-EULAR classification system in the diagnosis of IgG4-related disease (IgG4-RD).

METHODS

This retrospective single-institution study included patients who received a diagnosis of IgG4-RD between January 2010 and December 2020. Two abdominal radiologists independently reviewed baseline imaging studies and scored radiology findings according to the 2019 ACR-EULAR classification criteria. Additional scores were assigned based on serological, histopathological, and immunostaining features.

RESULTS

Seventy-four patients (58 males and 16 females) with a mean age of 59.3 ± 13.9 years diagnosed with IgG4-RD were included. 51/74 (68.9%) were classified as having IgG4-RD according to the 2019 ACR-EULAR classification criteria. To reach a score ≥ 20 in these 51 patients, the radiology domain was sufficient in 20/51 (39.2%) and adding the serology domain was required for another 20/51 (39.2%). The remaining 11/51 patients (21.6%) required the histopathology and immunostaining domains. Radiological involvement of two or more organs at presentation was significantly associated with a score of ≥ 20 and seen in 43/51 (84.3%) compared to 5/23 (21.7%) of the non-classified group (p < 0.001). The group classified as having IgG4-RD showed a significantly higher proportion of elevated IgG4 levels (39/51, 76.5%) than the non-classified group (8/23, 34.8%) (< 0.001).

CONCLUSION

The study findings support the effectiveness of the radiology-related inclusion criteria of the 2019 ACR-EULAR classification system in diagnosing IgG4-RD. Combining radiology and serology domains achieved the cut-off in 80% of IgG-RD patients, enabling non-invasive diagnosis. The classification of IgG4-RD was significantly associated with multi-organ involvement, particularly affecting the pancreas and biliary system.

CRITICAL RELEVANCE STATEMENT

This study is the first to evaluate the diagnostic performance of the radiology domain in the 2019 ACR-EULAR classification criteria. The study results confirm its utility and potential to enable non-invasive diagnosis when combined with serological testing in a significant proportion of patients.

KEY POINTS

• A significant proportion of patients can be diagnosed with IgG4-RD using the radiology and serology domains exclusively. • Multi-organ involvement is significantly associated with classifying patients as IgG4-RD, with the pancreas and biliary system most frequently affected. • A high level of inter-reader agreement in the scoring of the radiology domain supports its reliability.

Immunoglobulin G4-related hepatic artery aneurysm

A 49-year-old man who was a current smoker with a history of hypertension, dyslipidemia, and coronary artery disease after coronary stent placement presented because of abdominal and back pain. Contrast-enhanced computed tomography showed a 30-mm, large hepatic artery aneurysm. Resection of the aneurysm and autogenous vein bypass grafting was performed, which resulted in a successful outcome without any complications. Pathologic examination of the aneurysm confirmed that it was related to immunoglobulin G4 (IgG4). The patient's serum IgG4 level was within the normal range, and no other signs of IgG4-related organ lesions were observed.

Increased IgG4+ plasma cells are common in excised lymph nodes from children and adolescents without IgG4-related disease

Lymphadenopathy is a common finding in patients with IgG4-related disease (IgG4-RD) and often associated with increased IgG4+ plasma cells in this setting. The histologic features of so-called IgG4-related lymphadenopathy (IgG4-LAD) have seldom been investigated in children and adolescents, and step-wise progression to extranodal IgG4-RD has not been described. This study was performed to further evaluate the frequency, pathologic features, and clinical significance of IgG4-LAD-like histologic changes in the pediatric setting. We analyzed 37 benign lymph nodes collected semi-consecutively from children aged 0-18 years at our institution for both absolute and relative IgG4+ plasma cell abundance and recurrent histomorphologic patterns associated with IgG4-LAD. The combination of IgG4+/IgG+ plasma cell ratio >40% and IgG4+ plasma cell count ≥50 were considered as IgG4-LAD-like per expert consensus guidelines. Seven cases (19%) met both diagnostic criteria. The dominant histomorphologic patterns were follicular hyperplasia (n = 6), interfollicular expansion (n = 3), and progressive transformation of germinal centers (n = 3). Extranodal manifestations of IgG4-RD were not identified in this cohort (38 months average follow-up). Instead, clinical and laboratory findings indicated that lymph node enlargement in most patients could likely be attributed to alternative processes including antecedent dentistry, concurrent infection, and incipient Crohn's disease. Our findings suggest that the histologic features of IgG4-LAD are likely much more common in children and adolescents than previously recognized, often existing in complex with common reactive lymphadenopathies. The diagnostic value of routine immunohistochemical assessment for IgG4+ plasma cells in benign lymph nodes from pediatric patients without established extranodal IgG4-RD and/or other supportive clinical and laboratory data is therefore uncertain.

IgG4-related cholangitis - a mimicker of fibrosing and malignant cholangiopathies

IgG4-related cholangitis (IRC) is the major hepatobiliary manifestation of IgG4-related disease (IgG4-RD), a systemic fibroinflammatory disorder. The pathogenesis of IgG4-RD and IRC is currently viewed as multifactorial, as there is evidence of a genetic predisposition while environmental factors, such as blue-collar work, are major risk factors. Various autoantigens have been described in IgG4-RD, including annexin A11 and laminin 511-E8, proteins which may exert a partially protective function in cholangiocytes by enhancing secretion and barrier function, respectively. For the other recently described autoantigens, galectin-3 and prohibitin 1, a distinct role in cholangiocytes appears less apparent. In relation to these autoantigens, oligoclonal expansions of IgG4+ plasmablasts are present in patients with IRC and disappear upon successful treatment. More recently, specific T-cell subtypes including regulatory T cells, follicular T helper 2 cells, peripheral T helper cells and cytotoxic CD8+ and CD4+ SLAMF7+ T cells have been implicated in the pathogenesis of IgG4-RD. The clinical presentation of IRC often mimics other biliary diseases such as primary sclerosing cholangitis or cholangiocarcinoma, which may lead to inappropriate medical and potentially invalidating surgical interventions. As specific biomarkers are lacking, diagnosis is made according to the HISORt criteria comprising histopathology, imaging, serology, other organ manifestations and response to therapy. Treatment of IRC aims to prevent or alleviate organ damage and to improve symptoms and consists of (i) remission induction, (ii) remission maintenance and (iii) long-term management. Glucocorticosteroids are highly effective for remission induction, after which immunomodulators can be introduced for maintenance of remission as glucocorticosteroid-sparing alternatives. Increased insight into the pathogenesis of IRC will lead to improved diagnosis and novel therapeutic strategies in the future.

Imaging manifestations of IgG4-related disease

IgG4-related disease is a multisystem immune-mediated disorder associated with lesions manifesting an IgG4-rich plasma cell infiltrate and often raised serum IgG4 concentrations. The disease can mimic neoplastic, infective, and inflammatory processes due to features such as development of masses or organ enlargement. Prompt consideration of this diagnosis is essential to avoid unnecessary investigations and offer appropriate treatments, which can include steroids and other immunosuppressive agents. Although histology is typically diagnostic, imaging is critical to assess disease burden, determine biopsy targets, and evaluate response to treatment. Characteristic imaging features can also point towards the diagnosis in the absence of biopsy. This review highlights these features, as well as more atypical findings, grouped by organ or system. Differential diagnoses are emphasised. The full spectrum of imaging methods is discussed. Whole-body imaging with integrated 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET)/computed tomography (CT) has an evolving role in the detection of multi-organ involvement and subsequent follow-up.

Pancreatic cancer, autoimmune or chronic pancreatitis, beyond tissue diagnosis: Collateral imaging and clinical characteristics may differentiate them

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies and is developing into the 2^nd leading cause of cancer-related death. Often, the clinical and radiological presentation of PDAC may be mirrored by other inflammatory pancreatic masses, such as autoimmune pancreatitis (AIP) and mass-forming chronic pancreatitis (MFCP), making its diagnosis challenging. Differentiating AIP and MFCP from PDAC is vital due to significant therapeutic and prognostic implications. Current diagnostic criteria and tools allow the precise differentiation of benign from malignant masses; however, the diagnostic accuracy is imperfect. Major pancreatic resections have been performed in AIP cases under initial suspicion of PDAC after a diagnostic approach failed to provide an accurate diagnosis. It is not unusual that after a thorough diagnostic evaluation, the clinician is confronted with a pancreatic mass with uncertain diagnosis. In those cases, a re-evaluation must be entertained, preferably by an experienced multispecialty team including radiologists, pathologists, gastroenterologists, and surgeons, looking for disease-specific clinical, imaging, and histological hallmarks or collateral evidence that could favor a specific diagnosis. Our aim is to describe current diagnostic limitations that hinder our ability to reach an accurate diagnosis among AIP, PDAC, and MFCP and to highlight those disease-specific clinical, radiological, serological, and histological characteristics that could support the presence of any of these three disorders when facing a pancreatic mass with uncertain diagnosis after an initial diagnostic approach has been unsuccessful.

Patterns of Relapse and Complications of Immunoglobulin G4-Related Disease

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is a multisystemic fibroinflammatory condition potentially resulting in organ dysfunction. We aimed to evaluate imaging characteristics of disease relapse and complications in this cohort of patients.

METHODS

This was a cohort study of IgG4-RD patients imaged between 2010 and 2020. Radiological manifestations of disease activity (remission/stability vs. relapse and complications) were correlated with clinical symptoms. Univariate analyses were performed with χ2, Fisher exact, and Mann-Whitney U tests. Times to relapse and organ atrophy were studied with Kaplan-Meier analyses.

RESULTS

A total of 69 patients had imaging surveillance over a median duration of 47 months. Radiological relapse occurred in 50.7% (35/69) with median time to relapse at 74 months (95% confidence interval, 45-122 months); 42.8% (15/35) of this cohort had different-site relapse with the following recognized primary-secondary patterns: pancreas-hepatobiliary (p = 0.005), hepatobiliary-pancreas (p = 0.013), and periaortitis-mesenteric (p = 0.006). Clinical symptoms were significantly associated with imaging characteristics (p < 0.001). Abdominal complications were detected in 52.2% (36/69) of patients, mostly solid organ atrophy (97.2% [35/36]). New-onset diabetes was more likely in pancreatic IgG4-RD (n = 51) when accompanied by gland atrophy (4/21 vs. 0/30 nonatrophy, p = 0.024).

CONCLUSION

Radiological relapse of IgG4-RD is common over prolonged imaging surveillance and is significantly associated with symptomatic relapse. A multisystem review to detect new/different sites of disease and abdominal complications may help predict future organ dysfunction.

Anatomic and Functional Imaging of Immunoglobulin G4-related Disease and Its Mimics

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is an immune-mediated fibrosclerosing disease with tumefactive lesions infiltrated by IgG4-positive plasma cells. Initially described as autoimmune pancreatitis, IgG4-RD is now recognized as a discrete entity and is found to affect virtually any organ in the body. Common extrapancreatic sites include the biliary tree, salivary glands, periorbital tissue, lungs, kidneys, lymph nodes, aorta, retroperitoneum, and thyroid gland. Diagnosis-which relies on histopathologic, serologic, and radiologic features-can be challenging with the disease underdiagnosed, as IgG4-RD often mimics malignancy, infectious processes, or other immune-mediated conditions. Patients may present with signs of compression of nearby structures due to mass effect or with organ failure when the disease is left untreated. The clinical course is complex, with single- or multiorgan involvement and metachronous or synchronous occurrence of lesions. IgG4-RD responds well to glucocorticoid therapy, disease-modifying antirheumatic drugs, and B-cell-depleting biologic agents; prompt diagnosis is important to avoid delay in treatment and unnecessary pharmacologic or surgical intervention. While imaging features may not be specific for IgG4-RD, functional whole-body imaging with fluorine 18-fluorodeoxyglucose PET/CT is a useful adjunct for localizing extrapancreatic sites for biopsy, monitoring therapeutic response, and demonstrating disease relapse. The authors describe the pancreatic and extrapancreatic sites of involvement in IgG4-RD, with imaging features and patterns to aid in distinguishing IgG4-RD from its mimics through a multimodality approach with emphasis on functional imaging evaluation. ^©RSNA, 2023 Quiz questions in the supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Thoracoabdominal manifestations of immunoglobulin G4-related disease

Immunoglobulin G4-related disease (IgG4-RD) comprises a group of immune-mediated diseases that, until recently, were considered separate entities. These entities have a similar clinical presentation, serological findings, and pathogenesis, so they are currently considered a single multisystemic disease. The common characteristic is the infiltration of involved tissues by plasma cells and lymphocytes that are positive for IgG4. Three major criteria have been proposed for the diagnosis of IgG4-RD: clinical, laboratory, and histological. The pancreas is the organ that is most affected by IgG4-RD, which can simulate a tumor. In this respect, a series of signs could help us suspect that the pancreatic findings do not reflect a tumor (halo sign, duct-penetrating sign, absence of vascular invasion, etc.). The differential diagnosis is important to avoid unnecessary surgical interventions.

Diffuse Involvement of Pancreas is not Always Autoimmune Pancreatitis

RATIONALE AND OBJECTIVES

To determine the prevalence of diffuse involvement of pancreas and to identify the findings of malignancies using enhancement computed tomography (CT).

MATERIALS AND METHODS

A total of 1,0249 patients performed enhancement CT in our hospital over 62 months were investigated and the final study cohort includes 245 patients (170 males, 75 females; mean age, 56.94 ± 12.17 years). The reference standard is the final clinical/pathological diagnosis. The lesion-to-aorta enhancement ratio (LAR) on the pancreatic arterial phase, portal phase and delayed phase (DP) and the traditional CT findings were evaluated. Intergroup comparisons between malignancies and non-malignancies lesions were performed. Univariate and multivariate analyses were conducted to identify findings predicting malignancies.

RESULTS

The prevalence of malignancy was 45.3% (111/245) of diffuse enlargement of pancreas. All benign lesions were autoimmune pancreatitis 54.7% (n = 134). The most common malignant lesion was pancreatic ductal adenocarcinoma (n = 88, 35.9%). Other rare lesions with malignant potential included pancreatic neuroendocrine tumor (n = 11, 4.5%), lymphoma (n = 4, 1.6%), metastasis (n = 4, 1.6%), solid pseudopapillary neoplasm (n = 3, 1.2%) and acinar cell carcinoma (n = 1, 0.4%). Residual normal pancreas parenchyma, heterogeneity, short axis (cut-off value, 3.15 cm) and LARDP (cut-off value, 0.75) were independent predictors of malignancies. When the above predictors were combined, a sensitivity of 94.2%, a specificity of 90.8% were attained.

CONCLUSION

Diffuse involvement of the pancreas is rare and is not a specific sign of autoimmune pancreatitis, and it is associated with a wide spectrum of malignant conditions. Dynamic enhancement CT is helpful to identifying malignancies.

Pancreatic Neoplasms: CT Evaluation of the Uncommon Presentations of Common Lesions and Common Presentations of the Uncommon Lesions!

Pancreatic masses are commonly encountered entities in radiology practice. Pancreatic ductal adenocarcinomas (PDAC) are the commonest pancreatic malignancies that typically present as infiltrative hypodense focal masses in the pancreatic head, which are hypoattenuating to the pancreatic parenchyma on pancreatic parenchymal and venous phases. However, there are various atypical imaging features of PDACs that create a diagnostic dilemma like tumor in body or tail, diffuse glandular involvement, isoattenuating tumors, cystic changes, or calcifications. Also, few relatively uncommon pancreatic malignancies like pancreatic neuroendocrine tumors, cystic pancreatic tumors, pancreatic lymphoma, and pancreatic metastases present with overlapping features. Accurate radiological characterization of pancreatic masses is important for optimal management and prognostication. Thus, it is imperative for radiologists to be aware of all the uncommon presentations of common pancreatic lesions and common presentations of uncommon pancreatic lesions to avoid erroneous interpretations and establishing the correct diagnosis.

Pancreaticoduodenal Groove: Spectrum of Disease and Imaging Features

The pancreaticoduodenal groove (PDG) is a small space between the pancreatic head and duodenum where vital interactions between multiple organs and physiologic processes take place. Muscles, nerves, and hormones perform a coordinated dance, allowing bile and pancreatic enzymes to aid in digestion and absorption of critical nutrition. Given the multitude of organs and cells working together, a variety of benign and malignant entities can arise in or adjacent to this space. Management of lesions in this region is also complex and can involve observation, endoscopic resection, or challenging surgeries such as the Whipple procedure. The radiologist plays an important role in evaluation of abnormalities involving the PDG. While CT is usually the first-line examination for evaluation of this complex region, MRI offers complementary information. Although features of abnormalities involving the PDG can often overlap, understanding the characteristic imaging and pathologic features generally allows categorization of disease entities based on the suspected organ of origin and the presence of ancillary features. The goal of the authors is to provide radiologists with a conceptual approach to entities implicating the PDG to increase the accuracy of diagnosis and assist in appropriate management or presurgical planning. They briefly discuss the anatomy of the PDG, followed by a more in-depth presentation of the features of disease categories. A table summarizing the entities that occur in this region by underlying cause and anatomic location is provided. ^©RSNA, 2022.

18F-Fluorodeoxyglucose-PET-Computerized Tomography and non-Fluorodeoxyglucose PET-Computerized Tomography in Hepatobiliary and Pancreatic Malignancies

Molecular imaging with PET-computerized tomography (PET-CT) plays an important role in oncology. There is current and evolving evidence supporting the use of fluorodeoxyglucose (FDG) and non-FDG tracers in assessment patients with hepatobiliary and pancreatic cancers in various clinical scenarios. In this chapter, we discuss the advantages and limitations of FDG and non-FDG PET-CT in the management of patients with hepatobiliary and pancreatic cancers.

MRI features for differentiation of autoimmune pancreatitis from pancreatic ductal adenocarcinoma: A systematic review and meta-analysis

BACKGROUND AND AIMS

The accurate differential diagnosis between autoimmune pancreatitis (AIP) and pancreatic ductal adenocarcinoma (PDAC) is clinically important. We aimed to determine significant MRI features for differentiating AIP from PDAC, including assessment of diffusion-weighted imaging (DWI).

METHODS

We performed a systematic search using three databases. The pooled diagnostic odds ratio was calculated using a bivariate random effects model to determine significant MRI features for differentiating AIP from PDAC. The pooled sensitivity and specificity were calculated. The qualitative systematic review for DWI assessment was performed.

RESULTS

Of nine studies (775 patients), multiple main pancreatic duct (MPD) strictures, absence of upstream marked MPD dilatation, peripancreatic rim, and duct penetration sign were significant MRI features for differentiating AIP from PDAC. Absence of MPD dilatation had the highest pooled sensitivity (87%, 95% CI=68-96%), whereas peripancreatic rim had the highest pooled specificity (100%, 95% CI=88-100%). Of 12 studies evaluating DWI, seven reported statistically significant differences in apparent diffusion coefficient (ADC) values between AIP and PDAC; however, four reported lower ADC values in AIP than in PDAC, but three reported the opposite result.

CONCLUSION

The four significant MRI features can be useful to differentiate AIP from PDAC, but DWI assessment might be limited.

Radiomics and Its Applications and Progress in Pancreatitis: A Current State of the Art Review

Radiomics involves high-throughput extraction and analysis of quantitative information from medical images. Since it was proposed in 2012, there are some publications on the application of radiomics for (1) predicting recurrent acute pancreatitis (RAP), clinical severity of acute pancreatitis (AP), and extrapancreatic necrosis in AP; (2) differentiating mass-forming chronic pancreatitis (MFCP) from pancreatic ductal adenocarcinoma (PDAC), focal autoimmune pancreatitis (AIP) from PDAC, and functional abdominal pain (functional gastrointestinal diseases) from RAP and chronic pancreatitis (CP); and (3) identifying CP and normal pancreas, and CP risk factors and complications. In this review, we aim to systematically summarize the applications and progress of radiomics in pancreatitis and it associated situations, so as to provide reference for related research.

Immunoglobulin G4-related disease presenting as an intracranial mass extended from the infratemporal fossa

Background

Neurological manifestations in immunoglobulin G4-related diseases (IgG4-RD) are rare and documented in <2% of cases. It commonly involves pachymeninges forming hypertrophic pachymeningitis and rarely forms tumor-like masses.

Case Description

We present our experience with a biopsy-proven case of IgG4-RD presenting with an intracranial extradural tumor-like mass infiltrating the temporal lobe. The patient was treated with high doses of corticosteroids followed by slow tapering. The neurological manifestations gradually improved and resolved after 2 months with a cerebral MRI showing a significant reduction in the tumoral size.

Conclusion

When it comes to intracranial mass, IgG4-RD neuropathy is one of the rarest differential diagnoses for the central nervous system tumors. Early recognition of IgG4-RD and appropriate establishment of its long-term treatment may avoid unnecessary investigations and morbidity.

IgG4-Related Disease: A Clinical Case Series From a Tertiary Care Center in India

AIM

Immunoglobulin G4-related disease (IgG4-RD) is often an unrecognized, rare fibroinflammatory condition that can involve various organ systems. This study aimed to identify the different clinical patterns of this disease in a single center in North India.

METHODS

Patients were diagnosed on the basis of published diagnostic criteria for IgG4-RD. Patients' presenting complaints; epidemiologic profiles; and laboratory, radiologic, and histologic findings along with the treatment and outcomes were collected and analyzed.

RESULTS

In total, 70 patients were diagnosed with the disease. The female-to-male ratio was 0.94:1, and it increased with multiorgan involvement. The mean age of patients was 41.4 years, and the majority of the patients (65.7%) were younger than 50 years. Patients were diagnosed as possible (38.57%), probable (32.85%), and definite (28.57%) IgG4-RD. The incidence of the involvement of orbital and periorbital tissues was the highest (52.9%); however, 13% of the patients had multiple organ involvement. Patients with involvement of the retroperitoneal tissues and the lymph nodes were 8.5% and 5.7%, respectively. Increased serum IgG4 levels were found in 74.3% of the patients with single-organ involvement, whereas all patients with multiorgan involvement had increased IgG4 levels. The majority of patients (94.3%) required immunosuppressive medications along with corticosteroids. Azathioprine was the most commonly used (72.8%) immunosuppressive medication. Rituximab was used in 17.1% of the patients, of whom only one had multisystem involvement.

CONCLUSIONS

This study depicts the most common patterns of organ involvement, along with the epidemiologic, laboratory, histologic, and radiologic data and response to treatment, in IgG4-RD, with a definite ophthalmology referral bias.

Amendment of the Japanese consensus guidelines for autoimmune pancreatitis, 2020

In response to the latest knowledge and the amendment of the Japanese diagnostic criteria for autoimmune pancreatitis (AIP) in 2018, the Japanese consensus guidelines for managing AIP in 2013 were required to be revised. Three committees [the professional committee for developing clinical questions (CQs) and statements by Japanese specialists; the expert panelist committee for rating statements by the modified Delphi method; and the evaluating committee of moderators] were organized. Twenty specialists in AIP extracted the specific clinical statements from a total of 5218 articles (1963-2019) from a search in PubMed and the Cochrane Library. The professional committee made 14, 9, 5, and 11 CQs and statements for the current concept and diagnosis, extra-pancreatic lesions, differential diagnosis, and treatment, respectively. The expert panelists regarded the statements as valid after a two-round modified Delphi approach with individually rating these clinical statements, in which a clinical statement receiving a median score greater than 7 on a 9-point scale from the panel was regarded as valid. After evaluation by the moderators, the amendment of the Japanese consensus guidelines for AIP has been proposed in 2020.

Proposed nomogram predicting neoplastic ampullary obstruction in patients with a suspected ampulla of Vater lesion on CT

PURPOSE

To stratify and weigh the computed tomography (CT) imaging and clinical features differentiating a neoplastic ampullary obstruction from a non-neoplastic ampullary obstruction and to develop a nomogram for estimating individualized risk of neoplastic potential in patients with a suspected ampulla of Vater (AOV) lesion on CT.

METHODS

135 patients (92 non-neoplastic and 43 neoplastic) with a suspected ampullary obstruction on a CT scan between February 2015 and May 2019 were included after the exclusion criteria were applied. Significant imaging and clinical findings of the neoplastic lesions were assessed using univariate and multivariate logistic regression analyses. Based on the significant variables in the multivariate analysis, a nomogram was developed to predict neoplastic potential in patients suspected of ampullary obstruction. The area under the receiver operating characteristic curve (AUC) was used to assess the diagnostic value in the external validation cohort (36 non-neoplastic and 13 neoplastic).

RESULTS

The multivariate analysis revealed that the presence of an AOV mass (odds ratio (OR), 77.21; 95% confidence intervals (CI) 1.51-3950.38), AOV size > 12 mm (OR, 23.93; 95% CI 2.96-193.60), total bilirubin > 1.2 mg/dl (OR, 9.99; 95% CI 1.37-73.06) and age ≤ 63 years (OR, 7.52; 95% CI 1.33-42.48) were independent significant parameters that predicted a neoplastic lesion in the AOV. The AUC for the nomogram was 0.93 on the internal validation and 0.91 (95% CI 0.79-0.97) on the external validation.

CONCLUSIONS

A nomogram using imaging and clinical findings was useful to estimate a neoplastic ampullary obstruction in patients with a suspected AOV lesion on CT and suggests a further evaluation.

Autoimmune pancreatitis presenting as a pancreatic head mass

The diagnosis of autoimmune pancreatitis (AIP) is often difficult as the main differential diagnosis is pancreatic head adenocarcinoma. Some clinical, radiological, serological and histological criteria help in guiding the diagnosis. The serum gamma-globulin IgG4 dosage is the most sensitive and specific marker. The shape of the ductal stenosis in AIP is characteristic. The treatment is based on corticosteroids. We report the case of a 53-year-old woman, presenting with pancreatic head mass mimicking an adenocarcinoma.

Immunoglobulin G4-related systemic disease: mesenteric and peritoneal involvement with radiopathological correlation and differential diagnoses

Since its first introduction in 2003 by Kamisawa et al., IgG4-related disease has gained wide interest in the imaging community, and several manuscripts have been published regarding its imaging features. In addition to initial observations in the pancreaticobiliary system, it is now well known that the disease may involve every organ system in the body. There is not much information in the imaging literature about the involvement of mesentery, omentum, and peritoneum in this disease. This article aims to provide more information about the imaging findings of IgG4-related disease regarding these areas by making radiopathological correlations and discussing the possible differential diagnoses.

Immunoglobulin (Ig) G4-related sclerosing cholangitis in patients resected for presumed perihilar cholangiocarcinoma: a 10-year experience

Background

This study aimed to investigate the incidence of immunoglobulin (Ig) G4-related sclerosing cholangitis (IgG4-SC) in patients resected for perihilar cholangiocarcinoma (PHC) in a designated hospital from 2010 to 2019. We also aimed to evaluate the diagnostic dilemma of IgG4-SC clinically.

Methods

Between January 2010 and December 2019, all patients who underwent radical resection due to presumed PHC were included. Independent pathologists scored bile duct samples based on the International Consensus Pathology Criteria for IgG4-related Disease (ICPD).

Results

Of the 289 patients who underwent radical resection of primary liver cancer, 26 (9%) were diagnosed as benign, without histological evidence of malignancy, among them, 23 had sclerosing inflammation, 1 had cystadenoma, and 2 had xanthogranulomatous cholangitis. Additionally, 18 had a definitive diagnosis of IgG4-SC. The misdiagnosis rate was 19% (54/289), of which, 26 patients had benign disease, and 28 patients had malignancies.

Conclusions

It is difficult to distinguish IgG-SC from PHC. The misdiagnosis has resulted in a large number of ineffective hepatectomies. Improving the detection rate of serum IgG4 (sIgG4) may therefore avoid misdiagnosis, surgery, and life-threatening complications.

Cholangiocarcinoma - Part 2, Tumoral and Nontumoral Mimics and Imaging Features Helpful in Differentiation

Each of the 3 morphological subtypes of cholangiocarcinoma has a different set of imaging differentials. Emulators of mass-forming cholangiocarcinoma include other primary and secondary hepatic malignancies, benign tumors and tumor-like mimics such as abscess, hemangioma and confluent hepatic fibrosis. Benign inflammatory biliary strictures constitute the major differential of periductal-infiltrative type and intraductal calculi are the main consideration for intraductal-growth type. CT and MRI are the standard imaging tools for characterization of cholangiocarcinoma and differentiating it from close mimics. Here we will describe the various tumoral and non-tumoral mimics of cholangiocarcinoma and discuss specific imaging features useful in differentiation.

Abdominal immune-related adverse events: detection on ultrasonography, CT, MRI and 18F-Fluorodeoxyglucose positron emission tomography

Immune checkpoint inhibitor and chimeric antigen receptor T-cell therapies are associated with a unique spectrum of complications termed immune-related adverse events (irAEs). The abdomen is the most frequent site of severe irAEs that require hospitalization with life-threatening consequences. Most abdominal irAEs such as enterocolitis, hepatitis, cholangiopathy, cholecystitis, pancreatitis, adrenalitis, and sarcoid-like reaction are initially detected on imaging such as ultrasonography (US), CT, MRI and fusion 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)-CT during routine surveillance of cancer therapy. Early recognition and diagnosis of irAEs and immediate management with cessation of immune modulator cancer therapy and institution of immunosuppressive therapy are necessary to avert morbidity and mortality. Diagnosis of irAEs is confirmed by tissue sampling or by follow-up imaging demonstrating resolution. Abdominal radiologists reviewing imaging on patients being treated with anti-cancer immunomodulators should be familiar with the imaging manifestations of irAEs.

Clinical characteristics and long-term prognosis of autoimmune pancreatitis with renal lesions

Autoimmune pancreatitis (AIP) is recognized as the pancreatic manifestation of a systemic IgG4-related disease that can involve various organs, including the kidney. However, renal lesions tend to be overlooked when AIP is diagnosed, and the clinical characteristics and long-term prognosis of AIP with renal lesions are unclear. We retrospectively reviewed 153 patients with AIP diagnosed at our hospital with a median follow-up period of 41 months (interquartile range, 10–86) and classified them into two groups: the KD group (n = 17), with characteristic renal imaging features, and the non-KD group (n = 136). Serum IgG4 levels were significantly higher in the KD group (663 vs. 304.5 mg/dl, P = 0.014). No differences were observed between the two groups in terms of steroid treatment [14/17 (82.4%) vs. 112/136 (82.4%), P = 1] or in the number of patients who exhibited exacerbation of renal function during treatment [1/17 (5.9%) vs. 8/136 (5.9%), P = 1]. However, the cumulative relapse rate was significantly higher in the KD group [61% vs. 21.9% (3 years), P < 0.001]. Patients in the KD group had different clinical features with high relapse rates compared with those in the non-KD group, and thus, it is important to confirm the presence of renal lesions in AIP patients.

The role of EUS in diagnosing focal autoimmune pancreatitis and differentiating it from pancreatic cancer

Background and Objectives:

The clinical presentation of focal autoimmune pancreatitis (FAIP) and together with radiological overlap can mimic pancreatic cancer (PC). The aim of this study is to construct and validate a prediction model for differentiating FAIP from PC according to EUS characteristics.

Patients and Methods:

Ninety patients with FAIP and 196 patients with PC, who consecutively underwent EUS at our center from January 2013 to December 2018, were retrospectively included in the study. The enrolled patients were randomly divided into either a derivation sample or a validation sample. According to EUS characteristics, multivariate stepwise logistic regression and receiver operating characteristics (ROC) analyses were used to construct a prediction model in derivation sample, and then, the efficacy was assessed in validation sample.

Results:

EUS characteristics that were suggestive of FAIP included diffuse hypoechogenicity, hyperechoic foci/stands or lobularity (parenchymal heterogeneity), bile duct wall thickening and peripancreatic hypoechoic margin; and EUS features favoring PC included focal hypoechogenicity, absence of parenchymal heterogeneity, pancreatic duct dilation, and vessel involvement. The prediction model, with an area under the ROC curve of more than 0.95, had a good capability to distinguish FAIP from PC. By using the optimal cutoff value, the efficacy of model for diagnosing PC showed 83.7%–91.8% sensitivity and 93.3%–95.6% specificity.

Conclusions:

It is feasible to differentiate FAIP from PC based on EUS characteristics. The prediction model built in this study needs to be further confirmed by multicenter prospective researches.

IgG4-related disease: Changing epidemiology and new thoughts on a multisystem disease

IgG4-related disease (IgG4-RD) represents an immune-mediated fibroinflammatory condition with peculiar histopathologic changes that can affect various organs. In 2012 its unified nomenclature was published, which allows to abandon other synonymous names. Up to now, only little is known about its epidemiology around the world. However, although it is generally considered a rare condition, the number of patients with IgG4-RD is increasing enormously. Likewise, the annual number of publications on this subject has increased progressively. The spectrum of clinical manifestations in IgG4-RD is highly variable, depending on the severity of the disease as well as the presence of organ(s) involvement. This review gives an overview on changing epidemiology of IgG4-RD focusing the attention on the large cohorts of patients published in the literature.

Pathology of IgG4-related sclerosing mastitis

Immunoglobulin G4-related sclerosing mastitis (IgG4-RM) is a recently recognised member of the IgG4-related disease (IgG4-RD) family, a multisystem fibroinflammatory condition that can affect any organ system. IgG4-RM is rare and predominantly occurs in middle-aged women. It may present with painless palpable mass and/or lymphadenopathy thereby mimicking breast cancer. Although there is an abundance of literature describing the clinicopathological characteristics of IgG4-RD in a variety of organs, data on IgG4-RM are limited due to its rarity. This review describes the manifestation of the disease in the breast based on reported cases, emphasising the clinicopathological features, pathophysiology, differential diagnosis, treatment and prognosis.

Meta-analysis of CT and MRI for differentiation of autoimmune pancreatitis from pancreatic adenocarcinoma

OBJECTIVES

To systematically determine the diagnostic performance of computed tomography (CT) and magnetic resonance imaging (MRI) for differentiating autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC), with a comparison between the two imaging modalities.

METHODS

Literature search was conducted using PubMed and EMBASE databases to identify original articles published between 2009 and 2019 reporting the diagnostic performance of CT and MRI for differentiating AIP from PDAC. The meta-analytic sensitivity and specificity of CT and MRI were calculated, and compared using a bivariate random effects model. Subgroup analysis for differentiating focal AIP from PDAC was performed.

RESULTS

Of the 856 articles screened, 11 eligible articles are remained, i.e., five studies for CT, four for MRI, and two for both. The meta-analytic summary sensitivity and specificity of CT were 59% (95% confidence interval [CI], 41-75%) and 99% (95% CI, 88-100%), respectively, while those of MRI were 84% (95% CI, 68-93%) and 97% (95% CI, 87-99%). MRI had a significantly higher meta-analytic summary sensitivity than CT (84% vs. 59%, p = 0.02) but a similar specificity (97% vs. 99%, p = 0.18). In the subgroup analysis for focal AIP, the sensitivity for distinguishing between focal AIP and PDAC was lower than that for the overall analysis. MRI had a higher sensitivity than CT (76% vs. 50%, p = 0.28) but a similar specificity (97% vs. 98%, p = 0.07).

CONCLUSION

MRI might be clinically more useful to evaluate patients with AIP, particularly for differentiating AIP from PDAC.

KEY POINTS

• MRI had an overall good diagnostic performance to differentiate AIP from PDAC with a meta-analytic summary estimate of 83% for sensitivity and of 97% for specificity. • CT had a very high specificity (99%), but a suboptimal sensitivity (59%) for differentiating AIP from PDAC. • Compared with CT, MRI had a higher sensitivity, but a similar specificity.

Prevalence of histological features resembling autoimmune pancreatitis in neoplastic pancreas resections

AIMS

Types 1 and 2 autoimmune pancreatitis (AIP) can mimic pancreatic neoplasia. Due to the small quantity of tissue in mass-targeted pancreas biopsies, inflammatory features may raise the differential of AIP. However, the frequency of AIP-like histology in neoplastic pancreas is not well characterised. Therefore, the specificity of inflammatory lesions on biopsy with respect to the diagnosis of AIP is uncertain.

METHODS AND RESULTS

Neoplastic pancreas resections performed at our institution between 2008 and 2019 were retrospectively reviewed. Features of AIP types 1 and 2 were assessed in the non-neoplastic areas. If features of immunoglobulin (Ig)G4-associated AIP were seen, IgG4 immunohistochemistry was performed. We identified 163 neoplastic pancreas resections. Of these, 34 had one or more types of inflammatory lesions in non-neoplastic pancreatic tissue. Dense lymphoplasmacytic inflammation mimicking type 1 AIP was found in six cases with mild to moderately increased IgG4-positive plasma cells. Neutrophilic infiltrates in small intralobular ducts were found in 20 cases. Mild extralobular ductitis or duct microabscess was found in 10 specimens. Marked neutrophilic duct destruction that resembled granulocytic epithelial lesions was found in 12 cases. Some cases showed multiple features.

CONCLUSION

Approximately 20% of neoplastic pancreas resections showed focal areas that could raise the differential of AIP. More cases showed neutrophilic predominant inflammation as seen in type 2 autoimmune pancreatitis, compared to dense lymphoplasmacytic infiltrates seen in type 1 AIP. Pathologists must be cautious when making a diagnosis of AIP on biopsy tissue based on histological findings alone.

Immunoglobulin G4-related Disease of the Genitourinary System: Spectrum of Imaging Findings and Clinical-Pathologic Features

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory disease characterized by focal or diffuse organ infiltration of IgG4-bearing plasma cells. The diagnosis of IgG4-RD is based on a combination of clinical, serologic, radiologic, and histopathologic findings. IgG4-RD has been reported to affect almost all organ systems. The kidney is the most frequently involved of the genitourinary organs. The most common renal manifestation of IgG4-RD is IgG4-RD tubulointerstitial nephritis, followed by membranous glomerulonephropathy and, less frequently, obstructive nephropathy involving the renal pelvis, ureter, or retroperitoneum. Renal parenchymal lesions may appear as multiple nodular lesions, diffuse patchy infiltrative lesions, or a single nodular lesion. Multiple small nodular cortical lesions are the most common imaging findings of IgG4-RD involving the kidney. Renal pelvic, sinus, or perinephric lesions can also occur. IgG4-RD involvement of other genitourinary organs including the ureter, bladder, urethra, and male and female reproductive organs is rare compared with kidney involvement but may show variable imaging findings such as a localized mass within or surrounding the involved organ or diffuse enlargement of the involved organ. Imaging findings of IgG4-RD involving the genitourinary system are nonspecific but should be differentiated from inflammatory and neoplastic lesions that mimic IgG4-RD. The online slide presentation from the RSNA Annual Meeting is available for this article. ^©RSNA, 2020.

IgG4-related disease in the abdomen and pelvis: atypical findings, pitfalls, and mimics

IgG4-related disease (IgG4-RD) is a systemic, autoimmune, fibroinflammatory disease that can cause multi-organ damage. Although there have been many trials and studies since its recognition in 2003, there is still much that is unknown. Furthermore, IgG4-RD can affect any organ in the body and often has many mimics and alternative diagnoses, which can make for a challenging workup. Imaging plays a substantial role in the diagnosis of IgG4-RD and is often the first occasion where IgG4-RD comes into consideration. Thus, knowledge about the imaging findings of various manifestations of IgG4-RD can aid in the diagnosis and have a significant impact on patient management. In this article, we review the wide array of imaging findings, both typical and atypical, as well as possible mimics of IgG4-RD in the abdomen and pelvis.

Non-neoplastic cholangiopathies: an algorithmic approach

Cholangiopathies are chronic diseases that affect the bile ducts, comprising a heterogeneous group of progressive and potentially fatal entities. The diagnosis of these diseases is a great challenge for radiologists because of the overlapping of their clinical, biochemical, and imaging findings. Nevertheless, identifying the precise etiology is crucial, given that the therapeutic options are distinct and influence the prognosis of the patient. The purpose of this review article is to discuss some of the non-neoplastic causes of cholangiopathies and to provide a useful diagnostic algorithm.

Immunoglobulin G4-related cholecystitis mimicking a locally advanced gallbladder cancer-a case report and review of literature

Immunoglobulin G4 (IgG4)-related disease is a multi-organ immune-mediated condition that can mimic many inflammatory, malignant, and infectious disorders. Isolated IgG4-related cholecystitis without systemic manifestation is extremely rare. We report a rare case of IgG4-related disease with its clinical, radiological and histopathological findings involving only the gallbladder which presented initially as unresectable locally advanced gallbladder cancer on imaging but was diagnosed as IgG4-related cholecystitis preoperatively depending upon serum IgG4 levels and immunohistochemistry. Patient was successfully treated with steroids followed by simple cholecystectomy in view of symptomatic gallstones. Preoperative diagnosis is challenging for IgG4-related cholecystitis in view of mass like appearance of the lesion with surrounding invasion on imaging so most of the cases are reported postoperatively. Knowledge of this disease as differential for malignancy can save patients from extensive resections in view of its steroid responsive nature. Xanthogranulomatous cholecystitis mimicking gallbladder cancer can coexist with this disease.

IgG4 related disease in a seven year old girl with multiple organ involvement: A rare presentation

Autoimmune pancreatitis has been described as a pancreatic manifestation of immunoglobulin G4-related disease, which is characterized by typical histopathologic, radiologic, and clinical features. Immunoglobulin G4-related disease is usually accompanied by elevated serum immunoglobulin G4 level, and can involve multiple organ/systems. Immunoglobulin G4-related disease has rarely been reported in pediatric population. There are few reports of inflammatory bowel disease in association with immunoglobulin G4-related disease. We describe a 7-year-old girl who presented with pancreatitis and concurrent sclerosing cholangitis, and developed bloody diarrhea during follow-up. An endoscopic examination revealed inflammatory bowel disease, and later lacrimal gland involvement was also recognized. She was diagnosed as having immunoglobulin G4-related disease, and her clinical signs and symptoms improved dramatically after steroid treatment. Hence, awareness of the clinical picture is important and early diagnosis can prevent fibrosis and organ damage.

European Guideline on IgG4-related digestive disease - UEG and SGF evidence-based recommendations

The overall objective of these guidelines is to provide evidence-based recommendations for the diagnosis and management of immunoglobulin G4 (IgG4)-related digestive disease in adults and children. IgG4-related digestive disease can be diagnosed only with a comprehensive work-up that includes histology, organ morphology at imaging, serology, search for other organ involvement, and response to glucocorticoid treatment. Indications for treatment are symptomatic patients with obstructive jaundice, abdominal pain, posterior pancreatic pain, and involvement of extra-pancreatic digestive organs, including IgG4-related cholangitis. Treatment with glucocorticoids should be weight-based and initiated at a dose of 0.6-0.8 mg/kg body weight/day orally (typical starting dose 30-40 mg/day prednisone equivalent) for 1 month to induce remission and then be tapered within two additional months. Response to initial treatment should be assessed at week 2-4 with clinical, biochemical and morphological markers. Maintenance treatment with glucocorticoids should be considered in multi-organ disease or history of relapse. If there is no change in disease activity and burden within 3 months, the diagnosis should be reconsidered. If the disease relapsed during the 3 months of treatment, immunosuppressive drugs should be added.

Clinical and imaging features of IgG4-related kidney disease

PURPOSE

To assess the clinical and imaging features of IgG4-RKD for understanding and diagnosis of this disease.

METHODS

CT and MR images of 34 patients with IgG4-RKD were retrospectively analyzed by two radiologists in consensus.

RESULTS

The serum IgG4 level was found being increased in all patients. Renal involvement was bilateral (24/34, 70.6%) or unilateral (10/34,29.4%), multiple (29/34, 85.3%) or solitary (5/34, 14.7%). The lesions were wedge-shaped (21) or mass-like (4) in the renal parenchyma, whereas diffusely decreased renal density was noted in 2 patients. All lesions showed progressive contrast enhancement. The 4 mass-like lesions were misdiagnosed as renal malignancy. In 15 patients with follow-up imaging examinations, the number and size of renal lesions decreased after oral hormone treatment. The serum IgG4 levels were significantly decreased after therapy in all patients.

CONCLUSION

IgG4-RKD has various imaging appearances. Although the mass-like appearance mimics renal malignancy in some patients, progressive contrast enhancement in the lesion with elevated serum IgG4 suggests IgG4-RKD.

Mesenteric Amyloidosis: Radiologic Imaging with Pathologic Correlation

Amyloidosis is a rare disease that is characterized by abnormal deposition of amyloid proteins in tissues, resulting in local, or systemic disease. When localized, it can present as an amyloidoma. We report a case of mesenteric amyloidosis in an 80-year-old male who was found to have an incidental mesenteric mass that was biopsy-proven to represent non-light chain amyloid tissue.

Differentiation of focal autoimmune pancreatitis from pancreatic ductal adenocarcinoma

Autoimmune pancreatitis (AIP) is an inflammatory process of the pancreas that occurs most commonly in elderly males and clinically can mimic pancreatic adenocarcinoma and present with jaundice, weight loss, and abdominal pain. Mass-forming lesions in the pancreas are seen in the focal form of AIP and both clinical and imaging findings can overlap those of pancreatic cancer. The accurate distinction of AIP from pancreatic cancer is of utmost importance as it means avoiding unnecessary surgery in AIP cases or inaccurate steroid treatment in patients with pancreatic cancer. Imaging concomitantly with serological examinations (IgG4 and Ca 19-9) plays an important role in the distinction between these entities. Characteristic extra-pancreatic manifestations as well as favorable good response to treatment with steroids are characteristic of AIP. This paper will review current diagnostic parameters useful in differentiating between focal AIP and pancreatic adenocarcinoma.

Imaging diagnosis and staging of pancreatic ductal adenocarcinoma: a comprehensive review

Pancreatic ductal adenocarcinoma (PDAC) has continued to have a poor prognosis for the last few decades in spite of recent advances in different imaging modalities mainly due to difficulty in early diagnosis and aggressive biological behavior. Early PDAC can be missed on CT due to similar attenuation relative to the normal pancreas, small size, or hidden location in the uncinate process. Tumor resectability and its contingency on the vascular invasion most commonly assessed with multi-phasic thin-slice CT is a continuously changing concept, particularly in the era of frequent neoadjuvant therapy. Coexistent celiac artery stenosis may affect the surgical plan in patients undergoing pancreaticoduodenectomy. In this review, we discuss the challenges related to the imaging of PDAC. These include radiological and clinical subtleties of the tumor, evolving imaging criteria for tumor resectability, preoperative diagnosis of accompanying celiac artery stenosis, and post-neoadjuvant therapy imaging. For each category, the key imaging features and potential pitfalls on cross-sectional imaging will be discussed. Also, we will describe the imaging discriminators of potential mimickers of PDAC.

IgG4/IgG RNA ratio does not accurately discriminate IgG4-related disease from pancreatobiliary cancer

Background & Aims

IgG4-related disease (IgG4-RD) of the biliary tract and pancreas is often difficult to distinguish from pancreatobiliary cancer. The blood IgG4/IgG RNA ratio has been reported to discriminate IgG4-RD from primary sclerosing cholangitis/pancreatobiliary cancer with high accuracy. This study aimed to prospectively assess the diagnostic accuracy of the blood IgG4/IgG RNA ratio for distinguishing IgG4-RD from cancer in patients with a suspected pancreatobiliary malignancy.

Methods

In this prospective, single center, observational study, patients presenting at a specialized multidisciplinary, hepato-pancreato-biliary clinic with suspicion of pancreatobiliary malignancy were included. The IgG4/IgG RNA ratio (threshold 5.0%) was determined by quantitative PCR in addition to standard diagnostic procedures. Clinical, biochemical, radiological, and histo-/cytopathological findings were analyzed. For the diagnosis of IgG4-RD, the HISORt criteria were used as a reference standard. Malignancy was defined by the presence of neoplastic tissue at histo-/cytopathological examination.

Results

Overall, 213 consecutive patients (mean age 68 years) with a suspected pancreatobiliary malignancy were analyzed, of whom 3 patients were diagnosed with IgG4-RD and 178 patients were diagnosed with malignancy (165 patients with primary pancreatobiliary malignancy). The IgG4/IgG RNA ratio was true positive in 3 patients and false positive in 87 (40.8%) patients. In 123 (57.7%) patients the test was true negative. The sensitivity of blood IgG4/IgG RNA ratio was 100%, the specificity 58.6%, the positive predictive value 3.3%.

Conclusion

In the setting of a high a priori risk of malignancy, an elevated IgG4/IgG RNA ratio did not accurately discriminate pancreatobiliary cancer from IgG4-RD as illustrated by low specificity and concordant low positive predictive value. We advise against the use of this test to discriminate IgG4-RD from pancreatobiliary malignancies.

Lay summary

IgG4-related disease is a benign inflammatory multiorgan disease which predominantly affects the pancreas and biliary tree. Clinical symptoms, laboratory and imaging finding are often difficult to distinguish from pancreatic or biliary tract cancer. This prospective trial indicates that the recently proposed blood IgG4/IgG RNA ratio does not accurately distinguish benign IgG4-RD from malignant pancreatobiliary disease.

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IgG4-related disease and malignancy of bile ducts/pancreas can be indistinguishable.

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Blood IgG4/IgG RNA ratio was prospectively tested as an IgG4-RD marker when malignancy was suspected.

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IgG4/IgG RNA ratio >5% did not accurately discriminate IgG4-RD from pancreatobiliary cancer.

Non-neoplastic hepatopancreatobiliary lesions simulating malignancy: can we differentiate?

Despite the success of cross-sectional imaging in evaluating hepatopancreatobiliary system malignancies, several non-malignant disease processes may closely mimic malignancy. Differentiating these benign diseases from malignancy may be difficult, or even impossible, even in the hands of experienced imagers. In this manuscript, we present benign mimics involving the hepatopancreatobiliary system and try to increase awareness of these potential pitfalls.

Review of IgG4-related disease

IgG4-related disease is a fibrous-inflammatory process related to immunomodulation. The most commonly affected organs are: the pancreas, bile duct, major salivary glands, lacrimal glands, retroperitoneum and lymphatic ducts. In recent decades, this disease has been recognised as a systemic disorder that includes many single organ disorders, previously unrelated and known as independent entities. The common characteristics shared by the different entities that make up the IgG4-related disease are: raised serum IgG4 levels, alterations in the imaging tests with neoplastic-like swelling of the affected organs, specific histopathological characteristics and in immunostaining, as well as good response to treatment with glucocorticoids. In this work, we will review this pathology with a special emphasis on the characteristics of autoimmune pancreatitis, sclerosing cholangitis related to IgG4 and the involvement of the retroperitoneum, mesenterium and the digestive tract.

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.

Pancreatic tumor in type 1 autoimmune pancreatitis: a diagnostic challenge

Background

The co-occurrence of type 1 autoimmune pancreatitis (AIP) and pancreatic tumor (PaT) has been previously reported. Pure AIP cases have favorable prognosis and are primarily treated with steroids, while AIP cases with PaT are associated with poor prognosis where the primary management is pancreatic resection. However, it’s a challenge to timely identify the concurrent PaT in AIP because of their similar clinical and radiological manifestations.

Methods

We retrospectively reviewed the data in two medical centers from January 2010 to April 2019. The inclusion criteria were as follows: 1) completion of abdominal CT imaging before invasive procedures to the pancreas, 2) a final diagnosis of type 1 AIP using the 2011 international consensus diagnostic criteria, 3) follow-up duration of at least one month unless AIP and PaT were identified simultaneously. The presence of PaT in AIP was made based on histopathological confirmation, and the absence of PaT in AIP was defined as no pathological or radiological evidence of concurrent PaT. Clinical and radiological characteristics including gender, age, surveillance period, serum IgG4 and Ca-199 levels, biopsy, extrapancreatic involvement, CT and MR (if performed) imaging characteristics were compared between AIP with and without PaT. The Fisher’s exact test was used for qualitative variables, and nonparametric Mann-Whitney test for quantitative variables. A p value ≤0.05 was considered statistically significant.

Results

A total of 74 patients with type 1 AIP were included, of which 5 (6.7%) had the concurrent PaT. The subtypes were pancreatic ductal adenocarcinoma (3/5), solitary extramedullary plasmacytoma in the pancreas (1/5) and cholangiocarcinoma in the pancreatic segment (1/5), respectively. Gender (p = 0.044), the pattern of pancreatic enlargement (p = 0.003), heterogeneity (p = 0.015), low-density (p = 0.004) on CT and rim enhancement on MRI (p = 0.050) differed significantly between AIP with and without PaT. None of the low-density characteristics on CT or other assessed MRI characteristics could significantly differentiate the two groups (p>0.05).

Conclusions

Female, focal pancreatic enlargement, pancreatic heterogeneity, low-density on CT and rim enhancement on MRI are suggestive of the concurrent PaT in type 1 AIP. The characteristics of low-density on CT or other MRI characteristics did not provide further diagnostic values.

[Differential diagnosis of gallbladder abnormalities : Ultrasound, computed tomography, and magnetic resonance imaging]

CLINICAL ISSUE

Due to the high prevalence of clinically suspected cholecystitis or cholecystolithiasis the gallbladder is one of the organs examined the most by imaging.

STANDARD RADIOLOGICAL METHODS

In most clinical settings ultrasound is the primary imaging method because of its wide availability, speed and superior spatial resolution. In cases of ambiguous findings or potential complications computed tomography (CT) and magnetic resonance imaging (MRI) are used.

METHODICAL INNOVATIONS

When specific problems arise these imaging modalities may be enhanced by special techniques, e. g. contrast-enhanced ultrasound or dual-energy CT, and specific MRI sequences.

PERFORMANCE

Special variants of cholecystitis, such as xanthogranulomatous cholecystitis and adenomyomatosis, may pose a particularly difficult diagnostic problem as they may resemble other diseases. Sequelae of cholecystolithiasis, such as the Mirizzi syndrome and acute bowel obstruction, may complicate the imaging algorithm as the location and the symptoms shift. Cases of neoplastic diseases of gallbladder cancer and other malignancies require a broad spectrum of imaging modalities.

ACHIEVEMENTS

Although the gallbladder can easily be examined with ultrasound, some cases require a more thorough ultrasound examination. In some cases only a combination of multiple imaging modalities yield the diagnosis. Further developments regarding technical issues and the diagnostic algorithm can be expected.

PRACTICAL RECOMMENDATIONS

Ultrasound is the best first imaging modality. In cases of ambiguous findings or clinical complications CT or MRI are recommended.