Characteristics of immunoglobulin G4-related aortitis/periaortitis and periarteritis on fluorodeoxyglucose positron emission tomography/computed tomography co-registered with contrast-enhanced computed tomography

Imaging findings in cardiovascular involvements of IgG4-related disease: a systematic review study

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition characterized by IgG4-positive plasma cell infiltration that can affect multiple organs, including the cardiovascular system. The diagnosis of IgG4-RD relies on a combination of clinical, serological, radiological and pathological findings. However, due to the varied and insidious clinical presentations, normal IgG4 levels in a significant percentage of patients and frequent multi-organ involvement, imaging plays a crucial role in the diagnosis of IgG4-RD. The aim of this study is to comprehensively examine the imaging findings in IgG4-related cardiovascular disease for accurate diagnosis and appropriate treatment.

METHODS

A systematic search was conducted across the electronic databases PubMed, Scopus, Embase and Web of Science, to 1 September 2023, following PRISMA guidelines, searching for studies reporting detailed cardiovascular imaging findings in IgG4-RD.

RESULTS

The search yielded 68 studies (60 case reports, 5 case series, 2 cross-sectional, 1 case-control) with 120 cases of cardiovascular IgG4-RD. Most of the cases were male, averaging 62.8 years. The common initial symptoms were dyspnoea and chest pain. The most common imaging finding was vasculopathy, including vessel wall thickening, periarteritits, periaortitis, aortitis, stenosis, ectasia, aneurysm formation, intramural haemorrhage, fistula formation and dissection, followed by pericardial involvement and mediastinal masses. Case series and cross-sectional studies also showed vasculopathy to be the most common finding on various imaging modalities, including angiography and PET/CT, highlighting the complex pathology of IgG4-RD.

CONCLUSION

This study evaluated current IgG4-RD articles, revealing a higher prevalence in men and vasculopathy as the most common cardiovascular complication.

18F-Fluorodeoxyglucose Imaging for Assessing Cardiovascular Inflammation

Cardiovascular inflammation has recently emerged as a critical issue across various cardiovascular diseases. Various non-invasive imaging modalities are applied for assessing cardiovascular inflammation. Positron emission tomography (PET) using 18F-fluorodeoxyglucose (FDG) is a valuable non-invasive imaging tool for identifying active cardiovascular inflammation. It is utilized in evaluating conditions, such as cardiac sarcoidosis, endocarditis, vasculitis, and unstable atherosclerosis. Furthermore, management of cardiovascular complications after aggressive cancer therapy has increasingly been required in cancer patients. FDG PET is considered a suitable approach not only for the assessment of tumor responses to cancer therapy, but also for early and accurate detection of cardiovascular complications. This review highlights the clinical value of FDG PET under appropriate patient preparation. The future perspectives of new molecular imaging tools for assessing active cardiovascular inflammation have been described.

Multiple intrahepatic artery aneurysms during the treatment for IgG4-related sclerosing cholangitis: A case report

BACKGROUND

The purpose of this case report is to describe a case of multiple intrahepatic artery aneurysms during treatment for IgG4-related sclerosing cholangitis (IgG4-SC) and to provide information for daily practice.

CASE SUMMARY

A 64-year-old Japanese woman was diagnosed with IgG4-SC five years prior and was receiving maintenance treatment with prednisolone 7.5-10 mg/day. She developed abdominal pain and a sudden onset of black stool and was admitted to our hospital. Abdominal contrast-enhanced computed tomography (CT) and ultrasonography (US) revealed multiple intrahepatic artery aneurysms that developed during the treatment for IgG4-SC. Emergency transarterial embolization for multiple hepatic artery aneurysms was performed. Hepatic artery aneurysms disappeared on contrast-enhanced CT and US, the progression of anemia ceased, and the melena resolved. Thus, hemostasis was achieved.

CONCLUSION

Hepatic artery aneurysms should be considered poor prognostic complications of IgG4-SC.

Volume-Based Quantitative Measurement of [18F]AlF-NOTA-FAPI-04 PET/CT Uptake Reflects the Disease Activity of IgG4-Related Disease

BACKGROUND

To investigate the potential utility of quantitative parameters obtained by 18F-fibroblast activation protein inhibitor positron emission tomography/computed tomography ([18F]AlF-NOTA-FAPI-04 PET/CT) in the assessment of organ involvement and disease activity in IgG4-related disease (IgG4-RD).

METHODS

This study enrolled patients who underwent [18F]AlF-NOTA-FAPI-04 PET/CT scans at the Department of Rheumatology, The First Affiliated Hospital, Zhejiang University School of Medicine from August 2021 to August 2022. The PET/CT images of the included patients were re-evaluated by PET center technicians, and the maximal standardized uptake value (SUVmax), metabolic lesion volume (MLV), and total lesion FAPI (TL-FAPI) were used to evaluate the involved organs and tissues that abnormally accumulated [18F]AlF-NOTA-FAPI-04. The clinical and laboratory data of patients are also systematically collected and analyzed.

RESULTS

Among the patients included in this study, 12 patients met the IgG4-RD classification criteria established by the American College of Rheumatology in 2019. Among them, 8 were males and 4 were females, with an average age of 59.3 ± 11.5 years. 50% of IgG4-RD patients were found with more organ involvement on PET/CT than physical examination, ultrasonography, and computed tomography. IgG4 levels (Rho = 0.594, p = 0.042) and IgG4-RI (Rho = 0.647, p = 0.023) were significantly positively correlated with TL-FAPI. After linear regression analysis, only TL-FAPI showed a predictive value of RI (R2 = 0.356, B = 0.008, p = 0.041).

CONCLUSIONS

[18F]AlF-NOTA-FAPI-04 PET/CT is a useful tool for identifying asymptomatic organ involvement and assessing disease activity. The TL-FAPI as an indicator was positively correlated with IgG4-RD disease activity.

PET/CT in Inflammatory and Auto-immune Disorders: Focus on Several Key Molecular Concepts, FDG, and Radiolabeled Probe Perspectives

Chronic immune diseases mainly include autoimmune and inflammatory diseases. Managing chronic inflammatory and autoimmune diseases has become a significant public health concern, and therapeutic advancements over the past 50 years have been substantial. As therapeutic tools continue to multiply, the challenge now lies in providing each patient with personalized care tailored to the specifics of their condition, ushering in the era of personalized medicine. Precise and holistic imaging is essential in this context to comprehensively map the inflammatory processes in each patient, identify prognostic factors, and monitor treatment responses and complications. Imaging of patients with inflammatory and autoimmune diseases must provide a comprehensive view of the body, enabling the whole-body mapping of systemic involvement. It should identify key cellular players in the pathology, involving both innate immunity (dendritic cells, macrophages), adaptive immunity (lymphocytes), and microenvironmental cells (stromal cells, tissue cells). As a highly sensitive imaging tool with vectorized molecular probe capabilities, PET/CT can be of high relevance in the management of numerous inflammatory and autoimmune diseases. Relying on key molecular concepts of immunity, the clinical usefulness of FDG-PET/CT in several relevant inflammatory and immune-inflammatory conditions, validated or emerging, will be discussed in this review, together with radiolabeled probe perspectives.

Role of 18F-FDG PET/CT in Large Vessel Vasculitis and Polymyalgia Rheumatica

Systemic vasculitides comprise a group of autoimmune diseases affecting blood vessels, including large vessel vasculitis (LVV) and medium-sized vessel vasculitis such as giant cell arteritis (GCA) and Takayasu arteritis (TAK). GCA frequently overlaps with polymyalgia rheumatica (PMR), a rheumatic inflammatory condition affecting bursae, tendons or tendon sheaths, and joints. ¹⁸F-FDG PET/CT plays an important role in the diagnostic work-up of GCA, PMR, and TAK and is increasingly used to monitor treatment response. This continuing education article provides up-to-date guidance on the role of ¹⁸F-FDG PET/CT in patients with LVV, medium-sized vessel vasculitis, and PMR. It provides a general introduction on the clinical presentation and challenges in the diagnostic work-up of LVV and medium-sized vessel vasculitis, with a focus on the 2 major LVV subtypes: GCA, including PMR, and TAK. Next, practice points to perform and interpret the results of ¹⁸F-FDG PET/CT are described in line with the published procedure recommendations. Furthermore, the diagnostic performance and its role for treatment monitoring are discussed, taking into account recent international recommendations for the use of imaging in LVV and medium-sized vessel vasculitis in clinical practice. This is illustrated by several clinically representative PET/CT scan examples. Lastly, knowledge of limitations and pitfalls is essential to understand the role of ¹⁸F-FDG PET/CT in LVV, medium-sized vessel vasculitis, and PMR. Challenges and opportunities, as well as future research and conclusions, are highlighted. Learning objectives provide up-to-date guidance for the role of ¹⁸F-FDG PET/CT in patients with suspected LVV, medium-sized vessel vasculitis, and PMR.

Semi-quantitative indices of 2-[18F]FDG PET/CT in assessing cardiovascular and non-cardiovascular manifestations of IgG4-related disease and treatment response

BACKGROUND

IgG4-related disease (IgG4-RD) is a heterogeneous autoimmune disorder characterised by inflammatory lesions. Diagnostic imaging, such as 2-[¹⁸F]FDG PET/CT, is critical in evaluation of the disease, especially for potentially lethal cardiovascular manifestations. This retrospective study examines the usefulness of semi-quantitative parameters of 2-[¹⁸F]FDG PET/CT in monitoring IgG4-RD in patients with and without cardiovascular manifestations.

METHODS

Patients diagnosed with IgG4-RD who underwent a 2-[¹⁸F]FDG PET/CT scan were identified and classified based on presence or absence of cardiovascular disease. Clinical and laboratory data were extracted and compared to three 2-[¹⁸F]FDG PET/CT semi-quantitative parameters: maximum standardised uptake value (SUVmax), metabolic tumour volume (MTV), and total lesion glycolysis (TLG). Tissue-to-background blood (TBR) values were also evaluated for cardiovascular manifestations. These data were also compared in patients before and after receiving immunosuppressive therapy.

RESULTS

Forty-six patients identified were divided into an eight member subgroup of patients with cardiovascular manifestations, and a thirty-eight member subgroup of patients without. Patients with cardiovascular lesions were most frequently identified incidentally on imaging evaluation for other diseases (37.5%), with none presenting with chest pain or other cardiovascular symptoms. Ten patients with pre-treatment and post-treatment 2-[¹⁸F]FDG PET/CT scans demonstrated significant decreases in all semi-quantitative parameters, with no significant decrease in total IgG or ESR. The decrease in SUVmax, MTV, TLG following therapy was replicated in patients with and without cardiovascular manifestations.

CONCLUSION

2-[¹⁸F]FDG PET/CT is an important investigation to determine all sites of involvement in this multisystemic disease and to rule out life-threatening cardiovascular manifestations even in the absence of symptoms. Semi-quantitative parameters such as SUVmax, MTV, TLG, and TBR are useful in assessing treatment response in patients. There are no serological substitutes that can quantify the extent of disease involvement like 2-[¹⁸F]FDG PET/CT.

IgG4 related disease and aortitis: an up-to-date review

Aortic involvement in immunoglobulin G4-related disease (IgG4-RD) is extremely rare and is often overlooked during the aortitis work-up. IgG4-related aortitis differs from non-IgG4-related aortitis in its histopathological features, site of involvement, laboratory markers, and treatment options. The histopathological examination of the vessel walls characteristically reveals adventitial thickening with intimal sparing, typically affecting the infrarenal abdominal aorta. In addition, inadequate knowledge about the disease often leads to delayed or missed diagnosis and undermanagement of a potentially treatable condition. Hence, in this paper, we review the unique clinical manifestations, laboratory markers, diagnostic features, current treatment strategies, and novel experimental therapeutic options in the management of IgG4-related aortitis.

Positron Emission Tomography Imaging in Vasculitis

Systemic vasculitides comprise a group of autoimmune diseases affecting blood vessels. [18F]-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (FDG-PET/CT) plays an important role in the diagnosis and therapeutic monitoring of vasculitides affecting large-sized and medium-sized vessels. FDG-PET/CT also provides complementary information to other vascular imaging tools. The resolution and sensitivity of newer generation scanners continues to increase, hereby improving the ability of FDG-PET/CT to accurately assess the full disease extent in patients with vasculitis. Novel tracers targeting specific immune cells will allow for more detailed detection of vascular infiltrates.

Multidisciplinary diagnosis and management of inflammatory aortic aneurysms

BACKGROUND

Inflammatory abdominal aortic aneurysms (IAAAs) are a variant involving a distinct immunoinflammatory process, with nearly one half believed to be associated with IgG4-related disease (IgG4-RD).

METHODS

MEDLINE and Google Scholar searches were conducted for English-language publications relevant to inflammatory aortic aneurysms from January 1970 onward. The search terms included inflammatory aortic aneurysms, aortitis, periaortitis, IgG4-related disease, and retroperitoneal fibrosis. Relevant studies were selected for review based on their relevance.

RESULTS

Morphologically, IAAAs are characterized by a thickened aneurysm wall often displaying contrast enhancement and elevated metabolic activity on fluorine-18 fluorodeoxyglucose-positron emission tomography imaging. A strong association exists with perianeurysmal and retroperitoneal fibrosis. Although the rupture risk appears lower with IAAAs than with noninflammatory abdominal aortic aneurysms (AAAs), the currently recommended diameter threshold for operative management is the same. Open repair has been associated with increased morbidity compared with noninflammatory AAAs, and a retroperitoneal approach or minimal dissection transperitoneal approach has been recommended to avoid duodenal and retroperitoneal structural injuries. Endovascular aneurysm repair has been increasingly used, especially for patients unfit for open surgery. It is important to exclude an infectious etiology before the initiation of immunosuppressive therapy or operative repair. Multimodality imaging follow-up is critical to monitor disease activity and secondary involvement of retroperitoneal structures by the associated fibrotic process. Maintenance of immunosuppressive therapy will be needed postoperatively for most patients with active systemic disease, especially those with IgG4-RD and those with persistent symptoms. Additional interventions aimed at ureteral decompression could also be required, and lifelong follow-up is mandatory.

CONCLUSIONS

Preoperative multimodality imaging is a diagnostic cornerstone for assessment of the disease extent and activity. IgG4-RD is an increasingly recognized category of IAAAs, with implications for tailoring adjunctive medical therapy. Open surgical repair remains the procedure of choice, although endovascular aneurysm repair is increasingly being offered. Maintenance immunosuppressive therapy can be offered according to the disease activity as assessed by follow-up imaging studies.

Vascular/perivascular inflammation in IgG4-related disease

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is characterized by the infiltration of IgG4-positive plasma cells and fibrosclerotic inflammation in multiple organs. Although vascular complications are present in some patients with IgG4-RD, vascular and/or perivascular inflammatory activity compared to control subjects remains unknown. This study sought to investigate vascular/perivascular inflammation in IgG4-RD patients compared to control subjects using 18F-fluorodeoxyglucose-positron emission tomography combined with computed tomography (FDG-PET/CT).

METHODS

We examined 37 consecutive patients diagnosed as IgG4-RD (29 males, mean age of 64.3 ± 8.3 years old), who underwent FDG-PET/CT. Thirty-seven age- and gender-matched subjects without IgG4-RD were employed as controls. Vascular/perivascular inflammation was quantified by blood-normalized standardized uptake value, known as a target-to-background ratio (TBR).

RESULTS

All IgG4-RD patients presented with multiple region involvements. Twelve (32.4%) of the IgG4-RD patients had vascular complications, all of which appeared in the abdominal aorta. IgG4-RD patients had significantly higher TBR values in the descending aorta, abdominal aorta, and common iliac artery than control subjects. Also, IgG4-RD patients with vascular complication exhibited higher TBR values in the infra-renal aorta and common iliac artery than those without vascular complication.

CONCLUSIONS

We found that vascular FDG activity is significantly elevated in IgG4-RD patients regardless of vascular complication than control subjects. FDG-PET/CT is a useful modality for assessing vascular/perivascular inflammation, which may contribute vascular complication in IgG4-RD patients.

The role of PET/CT in large vessel vasculitis and related disorders: diagnosis, extent evaluation and assessment of therapy response

Large vessel vasculitides (LVV) are defined as chronic inflammatory disorders that affect the arteries with two major variants being distinguished: giant cell arteritis (GCA) and Takayasu's arteritis (TAK). These often present with nonspecific constitutional symptoms which makes an accurate diagnosis often challenging. Nevertheless, timely diagnosis is of utmost importance to initiate treatment and to avoid potential life-threatening complications. [¹⁸F]FDG-PET/CT is nowadays widely accepted as useful tool to aid in the diagnosis of large vessel vasculitis. However, its role to monitor disease activity and to predict disease relapse during follow-up is less obvious since vascular [¹⁸F]FDG uptake can be detected in the absence of clinical or biochemical signs of disease activity. In addition to the two major variants, [¹⁸F]FDG-PET/CT has shown promise in (peri-)aortitis and related disorders. This article aims to provide an update on the current knowledge and limitations of [¹⁸F]FDG-PET/CT for the diagnosis and assessment of treatment response in LVV. Furthermore, other radiopharmaceuticals targeting key components of the vascular immune system are being discussed which could provide an interesting alternative to image vascular inflammation in LVV.

18F-fluorodeoxyglucose PET and PET/computed tomography for the evaluation of immunoglobulin G4-related disease: a systematic review

BACKGROUND

In the last years, 18F-fluorodeoxyglucose PET/computed tomography (18F-FDG PET/CT) has demonstrated its utility for the evaluation of immunoglobulin G4 (IgG4)-related disease (IgG4RD). The studies are, however, really heterogeneous and different. The aim of this review is, therefore, to analyze the diagnostic performance of 18F-FDG PET and PET/CT for the assessment of IgG4RD.

METHODS

A wide literature search of the PubMed/MEDLINE, Scopus, Embase and Cochrane library databases was made to find relevant published articles about the diagnostic performance of 18F-FDG PET or PET/CT for the evaluation of IgG4RD.

RESULTS

The comprehensive computer literature search revealed 779 articles. On reviewing the titles and abstracts, 756 articles were excluded because the reported data were not within the field of interest. Twenty-three studies were included in the review.

CONCLUSION

Despite some limitations that affect our review, 18F-FDG PET or PET/CT demonstrated the ability to assess IgG4RD both at initial evaluation and after therapy. In general, no correlation between PET/CT parameters and IgG4 serum levels has been reported. A possible role for 18F-FDG PET/CT to drive differential diagnosis with other disease is starting to emerge.

2-deoxy-2[18F]fluoro-D-glucose positron emission tomography-computed tomography in rheumatological diseases

2-deoxy-2[18F]fluoro-D-glucose (FDG) PET-CT has revolutionized oncological imaging. The cellular processes that make cancer cells visible on FDG PET-CT also occur in a number of inflammatory cells. Exploiting this phenomenon has led to a growth of evidence supporting the use of FDG PET-CT in a wide range of infective and inflammatory diseases. Rheumatological diseases can affect multiple sites within the musculoskeletal system alongside multi-organ extra-articular disease manifestations. Inflammation is central to these diseases, making FDG PET-CT a logical choice. In this review article we describe the various applications of FDG PET-CT in rheumatological diseases using illustrative examples to highlight the beneficial role of FDG PET-CT in each case.

It's Not All in Your Head: Thoracic Manifestations of Neurologic Diseases and Disorders

Myriad conditions may affect both the neurologic system and the thorax, while other diseases primarily affecting the thorax may manifest with neurologic abnormalities. Correlation of signs, symptoms, and imaging findings in the neurological system with those in the thorax can help diagnose certain conditions and/or guide further diagnostic work-up and treatment. We will review and illustrate the imaging appearance of several systemic/neurological diseases with thoracic manifestations as well as discuss conditions in the thorax that can lead to neurologic symptoms.

Multisystem IgG4-related disease involving the abdomen and coronary arteries and causing chronic abdominal pain

IgG4-related disease was originally discovered in patients with autoimmune pancreatitis accompanied by elevated serum IgG4 levels and has subsequently been described in almost every organ system. IgG4-related disease presents with a variety of symptoms according to the organ affected and may be accompanied by serious complications such as organ dysfunction associated with IgG4-positive cell proliferation. We report a case of IgG4-related abdominal disease in a patient who also had involvement of the coronary artery.

Multiple Artery Aneurysms: Unusual Presentation of IgG4 Vasculopathy

Immunoglobulin G4 (IgG4)-related disease is a chronic systemic disease. It is characterized by inflammatory fibrosis and high serum IgG4 levels. IgG4-positive plasma cells infiltrate target organs in this disease. It may involve the pancreas, biliary tract, lacrimal glands, salivary glands, orbits, thyroid, kidneys, lymph nodes, or retroperitoneum. It may present as vasculitis with involvement of large to medium sized vessels such as the aorta, the common iliac, carotid, and coronary arteries. We present a case of 55-year-old male patient who presented with shortness of breath on exertion and atypical chest pain. On CT angiography, a giant coronary artery aneurysm involving the left anterior descending artery, multiple visceral and intercostal artery aneurysms, and nodular paravertebral soft-tissue thickening secondary to IgG4 vasculopathy.

IgG4 related disease

IgG4-related disease (ER-IgG4) is a recognised systemic disease. It was described after patients diagnosed with autoimmune pancreatitis showed signs of extra-pancreatic disease. The clinical manifestation of these patients is subacute and is manifested by the appearance of pseudotumoral lesions, or inflammatory or fibrous tumours. Sometimes it can be serious as in the case of patients with cholangitis or large vessel vasculitis. Diagnostic criteria include, among others, serum IgG4 elevation and/or histological parameters. The 18F-FDG-PET/CT is useful in the initial diagnosis, biopsy guidance as well as in the assessment of response to therapy. It usually responds to steroid therapy.

The enigmatic immunoglobulin G4-related disease and its varied cardiovascular manifestations

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory disease characterised by multiorgan lymphoplasmacytic infiltration, obliterative phlebitis and storiform fibrosis. It can be associated with cardiovascular pathology. The objective of this narrative review is to summarise the published literature on cardiovascular manifestations of IgG4-RD and to provide a basis for diagnosis and management of the condition by the practising cardiologist.We propose the following categorisations of cardiovascular IgG4-RD: aortitis, medium-vessel arteritis, pulmonary vascular disease, phlebitis, valvulopathy, pericarditis, myocardial disease and antineutrophilic cytoplasmic antibody-associated vasculitis. We also review herein developments in radiological diagnosis and reported medical and surgical therapies. Cardiovascular lesions frequently require procedural and/or surgical interventions, such as aortic aneurysm repair and valve replacement. IgG4-RD of the cardiovascular system results in serious complications that can be missed if not evaluated aggressively. These are likely underdiagnosed, as clinical presentations frequently mimic cardiovascular disease due to more common aetiologies (myocardial infarction, abdominal aortic aneurysm and so on). While systemic corticosteroids are the mainstay of IgG4-RD treatment, biological and disease-modifying agents are becoming more widely used. Cardiologists should be aware of cardiovascular IgG4-RD as a differential diagnosis, and understand the roles of corticosteroids, disease-modifying agents and biologicals, as well as their integration with surgical approaches. There are several knowledge gaps, including diagnosis, risk factors, pathogenesis and appropriate management in Ig4-RD of the cardiovascular system. Areas lacking well-conducted randomized trials include safety of steroids in the setting of vascular aneurysms and the role of disease-modifying drugs and biological agents in patients with established cardiovascular complications of this multifaceted enigmatic disease.

Disease activity and response to therapy monitored by [18F]FDG PET/CT using volume-based indices in IgG4-related disease

Purpose

The efficiency of [¹⁸F]FDG PET/CT using volume-based indices was evaluated to assess the disease activity and response to therapy in patients with immunoglobulin G4-related disease (IgG4-RD).

Methods

A total of 17 patients with IgG4-RD were examined with [¹⁸F]FDG PET/CT before and during treatment. The lesion boundary was determined using a fixed threshold of standardized uptake value (SUV) ≥ 2.5. The highest maximum SUV (SUVmax) among all affected lesions was calculated for individual patients. We summed metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of each affected lesion to generate a total MTV and total TLG. PET results were compared with those of serum IgG4 and soluble interleukin-2 receptor (sIL-2R) levels.

Results

The mean number of involved organs per patient was 3.8 as determined by [¹⁸F]FDG uptake. The number of involved organs, total MTV and total TLG were significantly correlated with IgG4 (P = 0.046, < 0.001, < 0.001, respectively) and sIL-2R (P < 0.001, = 0.031, 0.031, respectively). According to the clinical assessments for therapy response, all patients were classified as improved. The SUVmax, total MTV, and total TLG during therapy were all significantly lower than those before therapy (all P < 0.001).

Conclusion

[¹⁸F]FDG PET/CT is valuable for assessing the extent of multi-organ involvement before therapy and monitoring subsequent therapy in patients with IgG4-RD. [¹⁸F]FDG PET/CT using volumetric indices correlated with serum IgG4 and sIL-2R levels.

Overview of IgG4-related aortitis and periaortitis. A decade since their first description

Aortic involvement is relatively common in the context of IgG4-related disease (IgG4-RD). It includes IgG4-aortitis, and IgG4-(chronic) periaortitis (IgG4-CP). The latter overlaps with IgG4-retroperitoneal fibrosis (IgG4-RPF). Aortic wall thickening which characterizes these entities along with the presence of periaortic tissue in IgG4-CP, are often accompanied by aortic aneurysms, which belong to the group of the so-called inflammatory aneurysms. Both the thoracic and abdominal aorta can be affected. Aortitis appears to involve more often the former, while the opposite is the case for IgG4-CP. There is a lack of definitions and different classification criteria have been used to describe these entities. This report provides an overview on the current evidence of aortic involvement in IgG4-RD. It discusses the clinical, epidemiologic, serologic and histopathologic characteristics, as well as the imaging techniques used for their diagnosis and the therapeutic options and treatment outcomes. The differential diagnosis and underlying pathogenetic mechanisms are also discussed.

Immunoglobulin G4-related thoracic aortitis

Patients with immunoglobulin G4-related thoracic aortitis often have nonspecific symptoms, but pain in the chest or back is common. The rate of misdiagnosis of immunoglobulin G4-related thoracic aortitis is high, which may lead to mistreatment in extreme cases. A correct diagnosis should be based on comprehensive medical imaging, pathology, and laboratory and immunohistochemical results. Most patients' condition can be significantly improved using conservative or surgical treatment.

Exacerbation of immunoglobulin G4-related inflammatory abdominal aortic aneurysm after endovascular repair

A 78-year-old male was admitted to our hospital with lumbar pain and was found to have an abdominal aortic aneurysm (AAA) and femoral artery aneurysm (FAA). Initially, the patient underwent endovascular aneurysm repair (EVAR) for the AAA and aneurysmectomy for the FAA. The FAA was diagnosed by histology as immunoglobulin G4-related disease (IgG4-RD). The preoperative serum IgG4 level was within the normal range, although a slight serum interleukin-6 (IL-6) elevation was observed. Four years later, the AAA-sac diameter had expanded and the serum levels of both IgG4 and IL-6 levels had increased. Six years after the initial EVAR, aneurysmorrhaphy of AAA-sac was performed. The resected specimen revealed adventitial fibrosis and prominent lymphoplasmacytic infiltrate with regulatory T cells, satisfying histological diagnostic criteria for IgG4-RD. Immunoreactive matrix metalloproteinases (MMPs), particularly MMP-2 and MMP-9, and IL-6 were detected within numerous spindle cells in the adventitia of both the FAA and the AAA-sac. Five months after the aneurysmorrhaphy, the residual AAA-sac was again enlarged with a thickened wall that accumulated [¹⁸ F] fluoro-2-deoxy-D-glucose (FDG-PET) on positron emission tomography; these findings were paralleled by increased levels of serum IgG4 and IL-6. Therefore, persistent inflammation after EVAR may be attributed to the inflammatory sequelae of IgG4-RD.

[Raynaud phenomenon with arterial thromboses and IgG4-related disease]

INTRODUCTION

This is a clinical case illustrating a diagnosis of an IgG4 related-disease (IgG4-RD) diagnosed in a vascular context.

CASE REPORT

A 47-year-old man with no past medical history consulted for a recent and disabling Raynaud phenomenon without trophic disorder. Vascular examinations revealed multiple arterial thromboses with no abnormal finger and toe pressures. Secondly, weight loss and submandibular glands enlargement appeared, leading to the diagnosis of IgG4-RD without a link being able to be established with vascular involvement. This is the second observation of this association. A French translation of the new classification criteria for IgG4-RD published in 2019 by the American College of Rheumatology and European Ligue Against Rhumatism (ACR/EULAR) is offered with direct application to the clinical case.

CONCLUSION

A Raynaud phenomenon with distal arterial thrombosis is rarely observed in the IgG4-RD.

Vasculitis beyond aortitis in IgG4-related disease (IgG4-RD): case report and review of the literature

IgG4-related disease (IgG4-RD) can affect almost every tissue/organ. Vascular involvement in the setting of IgG4-RD is increasingly being recognized with most of the cases pertaining patients with aortitis and/or periaortitis with or without aneurysm formation. However, it is now evident that other vessels like iliac arteries, coronary arteries, carotids, and others can also be affected being often underdiagnosed. Vascular involvement is expressed as vessel wall thickening, while aneurysm formation is also occasionally seen. Although histopathological findings are the cornerstone in the diagnosis of IgG4-RD, imaging modalities like magnetic resonance imaging (MRI) and positron emission tomography (PET) are similarly important when vascular involvement occurs, helping in the mapping of the disease and in identifying other, more accessible to biopsy, affected organs. Inflammation markers like erythrocyte sedimentation rate and C-reactive protein have also been described in IgG4-RD patients with vascular involvement. Herein, we present a case of a middle-aged man with long-term high inflammation markers who eventually diagnosed with IgG4-RD after an ascending aorta aneurysm operation, while a subsequent comprehensive magnetic resonance angiography revealed also involvement of the abdominal aorta and the left subclavian and left common carotid. Moreover, we sought to review the current literature about medium- and large-vessel involvement, beyond the aorta, in patients with IgG4-RD.

Adventitial matrix metalloproteinase production and distribution of immunoglobulin G4-related abdominal aortic aneurysms

Objective

IgG4-related diseases are systemic inflammatory fibrous lesions characterized by elevated serum IgG4 and infiltration of IgG4-positive plasmacytes. They can manifest in vascular lesions as frequently formed aneurysms with prominent thickening of the adventitia (IgG4-related abdominal aortic aneurysm; IgG4-AAA). Matrix metalloproteinases (MMPs) degrade the extracellular matrix, mainly in the tunica media, resulting in destruction of aortic structures to cause enlargement of the aneurysm. However, the expression of adventitial MMPs in IgG4-AAAs is poorly understood.

Methods

MMPs and MMPs-presenting cells in the adventitia of IgG4-AAAs (n = 19) of human surgical specimens were evaluated by immunohistochemistry and dual messenger RNA in situ hybridization. The results were compared with those from control groups of non-IgG4-related inflammatory AAA (n = 18), atherosclerotic AAA (aAAA; n = 11), and autopsy cases (n = 11). Preoperative serum MMPs levels of these groups were compared with the histologic data.

Results

Expression of MMP-9, MMP-2, and MMP-14 at the protein and messenger RNA levels in the adventitia was significantly higher in IgG4-AAAs than in controls. Other MMPs were scarce. The total number of MMP-9-positive cells was positively correlated with the diameter of the aneurysm (R = 0.461; P = .031), the adventitial thickness (R = 0.688; P < .001), and the number of IgG4-positive cells (R = 0.764; P < .001). Within lymphoid follicles, MMP-9-presenting cells were predominantly detected in large follicular dendritic cells, followed by histiocytes, fibroblasts, and plasmacytic dendritic cells. Outside lymphoid follicles, fibroblasts, and histiocytes mainly expressed MMP-9, and tissue dendritic cells also produced MMP-9. The levels of MMP-9 derived from follicular dendritic cells and histiocytes and plasmacytic dendritic cells outside lymphoid follicles were significantly higher in IgG4-AAA group than in other groups. Expression of adventitial MMP-2 and MMP-14 by histiocytes and fibroblasts was predominantly detected outside lymphoid follicles. Serum MMP-9 levels were significantly higher in IgG4-AAAs (835 ng/mL) than in controls, and correlated with serum IgG4 levels and the total numbers of adventitial MMP-9-positive cells, whereas serum MMP-2 levels did not differ among the three aneurysmal groups.

Conclusions

MMP-9 production in adventitial immune cells concerning lymphoid follicles was characteristic of IgG4-AAAs and might work in its activity with aneurysmal dilatation and adventitial thickening. Expressions of adventitial MMP-2 and MMP-14 were detected in histiocytes and fibroblasts outside lymphoid follicles, and were less concerned with the activity of IgG4-AAAs.

This retrospective multicenter study analyzed adventitial matrix metalloproteinases (MMPs) production in 19 patients with IgG4-related abdominal aortic aneurysms (AAAs) and 40 control cases. Adventitial MMP-9 production by various kinds of immune cells was increased in patients with IgG4-related AAAs and concerned with IgG4-AAA activity to cause aneurysmal progression and adventitial fibrosis, compared with aAAA. Serum MMP-9 levels reflected histologic MMP-9. Adventitial MMP-2 and MMP-14 were less concerned with IgG4-AAA activity. Thus, for IgG4-AAA patients, monitoring serum MMP-9 level might be the exacerbating factors related to adverse events during the treatment course.

IgG4-related disease with elevated adenosine deaminase in pleural effusion diagnosed clinically using thoracoscopy under local anesthesia and FDG-PET-CT

In general, we have to assume tuberculous pleurisy when a patient presents with pleural effusion and elevated adenosine deaminase (ADA). However, other diseases need to be considered, including immunoglobulin (Ig)G4-related disease (IgG4-RD). This case involved a 65-year-old asymptomatic man with right pleural effusion showing elevated ADA. He had no articular findings or rashes. Results were negative for all autoantibodies. Pleura, mediastinal lymph nodes, and areas around the aorta and vertebra showed high uptake of ¹⁸F-fluorodeoxyglucose (FDG) on positron-emission tomography-computed tomography (PET-CT). These findings were specific for IgG4-RD. Based on the results of FDG-PET-CT, we performed thoracoscopy under local anesthesia and bronchoscopy. Pleural biopsy and culture, and other examinations including sputum and blood yielded negative findings for tuberculous pleurisy. A pleural biopsy specimen showed IgG4-positive plasma cells and fibrosis without obliterative phlebitis or storiform fibrosis, and serum IgG4 was also high. The ratio of IgG4-to IgG-positive plasma cells was under 40%, and >10 IgG4-positive cells were seen in high-power fields. This case was classed as ‘possible IgG4-RD’ on the comprehensive diagnostic criteria for IgG4-RD, but did not meet the diagnostic criteria for IgG4-related respiratory disease. Prednisolone proved effective against the pleural effusion. We therefore clinically diagnosed IgG4-RD with pleural effusion based on the 2019 classification criteria for IgG4-RD in the United States. Although few cases of IgG4-RD with pleural effusion have been reported, this disease needs to be considered among the differential diagnoses for high-ADA pleural effusion. FDG-PET-CT and thoracoscopy under local anesthesia may be helpful for diagnosis.

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ImmunoglobulinG4-related disease (IgG4-RD) with pleural effusion is rare.

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We should assume IgG4-RD as one of the differential diagnoses of pleural effusion with high level of adenosine deaminase.

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Thoracoscopy under local anesthesia and 18F-Fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET-CT) may be useful as an adjunctive tool for making a diagnosis of IgG4-RD.

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We could diagnosed as IgG4-RD with pleural effusion based on findings of FDG-PET-CT and thoracoscopy, and the responsiveness to prednisolone.

Cardiovascular and Lung Involvement in Patients with Autoimmune Pancreatitis

INTRODUCTION

Immunoglobulin G4-related disease (IgG4-RD) is a systemic immune-mediated disease characterised pathologically by the infiltration of IgG4-bearing plasma cells into the involved organs. Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis with a heavy lymphocytic infiltration and two distinct histopathological subtypes, namely: lymphoplasmacytic sclerosing pancreatitis (AIP type 1) and idiopathic duct-centric pancreatitis (AIP type 2). Lung involvement and aortic involvement have been reported in 12% and 9% of patients with systemic IgG4-RD, respectively. In series including patients with AIP, both lung and aortic involvement were described in 2% of the patients. Most of the epidemiological data come from Japan, and there is a lack of information from Europe, especially the Scandinavian countries.

PATIENTS AND METHODS

We performed a single-centre retrospective study on a prospectively collected cohort of patients diagnosed with AIP at the Department for Digestive Diseases at Karolinska University Hospital in Stockholm, Sweden, from 2004 to 2019. Demographic and clinical data were collected from the medical charts.

RESULTS

One hundred and thirty-three patients with AIP were analysed. Six patients were excluded because they lacked some of the clinical data relevant to the study. Demographic and clinical features of 127 patients were presented. There were 98 patients with AIP type 1-35 (35.7%) female and 63 (64.3%) male, with a mean age of 55.4 ± 18.2. Among them, 15 (15.3%) patients had lung and/or cardiovascular involvement-11 (11.2%) patients had lung involvement, 10 (10.2%) patients had cardiovascular involvement (six patients had both). Most of them (67.0%) had never smoked. The mean follow-up time of the patients with AIP type 1 was 49 months.

CONCLUSIONS

Lung and/or cardiovascular involvement were diagnosed in 15 (15.3%) patients in our historical cohort of patients with AIP type 1. Most of the lung involvement was presented in the form of nodular lesions in the lungs, non-specific infiltrates, "ground-glass" appearance with pleura thickening, and effusion. Aortic involvement was a major form of vascular involvement in patients with AIP, as in previous published studies on patients with IgG4-RD.

Association of IgG4-Related Arteritis With Recurrent Stroke

Immunoglobulin G4-related disease (IgG4)-related disease is a newly recognized form of immune-mediated disease, which is characterized by IgG4+ lymphoplasmacytic infiltration and fibrosis in the systemic organs. Although aortitis/periaortitis is a phenotype of IgG4-related disease, the relationship between cerebrovascular disease and IgG4-related disease remains unclear. Herein, we report the case of a 49-year-old man with recurrent stroke induced by IgG4-related arteritis. Case reports or studies examining the association between IgG4-related arteritis and stroke are limited. Although a definitive link between IgG4-related arteritis and stroke has not been established, IgG4-related arteritis should be considered as an etiology in patients with recurrent idiopathic stroke.

Characteristics and prognosis of IgG4-related periaortitis/periarteritis: A systematic literature review

OBJECTIVE

Immunoglobulin G4 (IgG4)-related disease is a systemic chronic fibroinflammatory disease that can affect almost every organ of the body. IgG4-related periaortitis/periarteritis is a newly recognized subset of IgG4-related disease, and its characteristics and prognosis remain unclear. We investigated the clinical characteristics and prognosis of IgG4-related periaortitis/periarteritis.

METHODS

We performed a systematic literature review of IgG4-related periaortitis/periarteritis. Additionally, we have summarized the characteristics and prognosis of IgG4-related coronary arteritis.

RESULTS

We investigated 248 patients with IgG4-related periaortitis/periarteritis. All studies reported the condition in elderly patients, and male predominance was observed. The infra-renal abdominal aorta and iliac arteries were the most commonly affected sites. Most reports showed the serum C-reactive protein elevation in this disease entity, in contrast to non-vascular IgG4-related disease. Based on radiological findings observed in 27 patients with IgG4-related coronary arteritis, vasculitic lesions were classified into 3 types: stenotic (67% of patients), aneurysmal (42%), and diffuse wall thickening type (92%). Serum IgG4 level, but not C-reactive protein level, was associated with the number of affected organs in IgG4-related coronary arteritis. Corticosteroid treatment with or without cardiac surgery or percutaneous coronary intervention was effective in most patients with IgG4-related coronary arteritis; however, 33% of patients showed an unfavorable clinical course including disease progression, relapse, or death. Pre-treatment stenosis and/or aneurysms were associated with progression of stenosis or aneurysm after corticosteroid treatment.

CONCLUSION

Most clinical characteristics were similar between the IgG4-related periaortitis/periarteritis and the non-vascular IgG4-related disease groups; however, serum C-reactive protein level elevation was observed only in the former. Although corticosteroid treatment was effective, this disease can be life-threatening secondary to myocardial infarction, aortic dissection, and aneurysmal rupture. Pre-treatment evaluation of stenosis or aneurysms is important for predicting progression of stenosis or aneurysm after corticosteroid treatment.

Therapeutic response of immunoglobulin 4-related aortitis and pancreatitis demonstrated by diffusion-weighted MRI

Immunoglobulin (IgG) 4-related disease is a systemic inflammatory disease, and it affects vascular system as aortitis, periaortitis, or aneurysm. However, due to a lack of serum biomarker on aortic damage and the multiorgan involvement, it is difficult to assess aortic inflammatory activity of IgG4-related disease. We described a case of IgG4-related pancreatitis and aortitis, which was visualized with magnetic resonance merged image of diffusion weighted and T₁ weighted images. The aortic signal intensity or apparent diffusion coefficient value reduced or increased after oral prednisone administration, respectively. Magnetic resonance diffusion weighted image and apparent diffusion coefficient may be a useful imaging tool for assessment of vascular inflammation in IgG4-related aortitis.

Detection of Inflammatory Aortopathies Using Multimodality Imaging

Diagnosis of the inflammatory aortopathies and importantly, their distinction in the later stages of disease from genetically mediated or acquired (degenerative) aortopathy remains a challenging clinical problem. Historically, the diagnosis of inflammatory aortopathy has required tissue sampling and pathological assessment. Although histological diagnosis remains an important diagnostic criterion, the ability to obtain sufficient tissue samples is problematic and requires invasive approaches that pose important risk. Continuing refinement in the capabilities of multimodality imaging, including ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography provides important insights into the broad spectrum of disease which comprise the inflammatory aortopathies. This review examines the current and emerging role of multimodality imaging in the evaluation of aortitis.

IgG4-aortitis among thoracic aortic aneurysms

Objective

The incidence of aortitis in patients with thoracic aortic diseases is not well established. The aim of this study was to analyse the frequency and clinical course of patients with aortitis in a surgical series.

Methods

320 consecutive patients with ascending aorta/aortic arch aneurysm or acute aortic syndrome who underwent surgery from 2012 to 2017 in a single tertiary referral hospital were retrospectively reviewed. Epidemiological data, clinical course and variables related to diagnosis, treatment and follow-up were collected from patients with histologically proven aortitis.

Results

From 320 examined aortic samples, 279 (87.2%) thoracic aneurysms and 41 acute aortic syndromes (12.8%), 9 (2.8%) were aortitis: 3 cases of Takayasu’s arteritis, 3 of IgG4-related aortitis, 2 of giant cell, and 1 classified as idiopathic. Median age at surgery was 53.4 (51–69.2) years and six cases were female. Seven patients presented with non-specific symptoms and the diagnosis was made at pathology. Surgery was elective in eight patients and emergent in one case of IgG4-related aortitis. 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT) was performed for disease extension study and as a monitoring technique during the follow-up of five patients, with just one case performed presurgically. All the patients with IgG4-related disease showed extrathoracic aortic involvement. There were no deaths, neither in-hospital nor during the 1.7 years of median follow-up.

Conclusions

In surgically treated thoracic aorta pathology, the frequency of aortitis is low; IgG4-related disease is among the most common aetiologies with a frequency similar to other types of aortitis, such as Takayasu’s and giant cell arteritis, and clinical manifestations are non-specific making presurgical diagnosis difficult. 18F-FDG PET/CT allows a better assessment of disease extension and therapeutic response. Surgery can be successfully performed and corticosteroid therapy ensures a good mid-term follow-up.

Abdominal aortic aneurysm as an IgG4-related disease

The objectives of this study were to evaluate patients with aortic abdominal aneurysm (AAA) with regard to immunoglobulin (Ig)G4‐related disease (IgG4‐RD). IgG4‐RD represents a recently defined condition comprised of a collection of disorders characterized by IgG4 hypergammaglobulinemia, the presence of IgG4‐positive plasma cells in organs affected with fibrotic or sclerotizing changes and typical histopathological features. It was identified as a possible cause of vasculitis in large vessels. Studies have been published on a possible association between inflammatory aortic or cardiovascular disease and IgG4‐RD. We examined 114 patients with AAA requiring surgery in order to identify findings which are characteristic of IgG4‐RD. Aneurysm samples from seven patients showed histopathological features consistent with IgG4‐RD and the presence of IgG4⁺ plasma cells. Only two of these seven patients showed elevated IgG4 serum levels higher 1·35 g/l. In five of the patients, the concentration of serum IgG4 was lower than 1·20 g/l, with the number of IgG4⁺ plasma cells being higher than 50/high‐power field. These findings were consistent with AAA being a heterogeneous group of inflammatory diseases with different pathogenesis.

Hybrid treatment of an isolated immunoglobulin G4-related internal thoracic artery aneurysm

True aneurysms of the internal thoracic artery (ITA) are rare and are associated with vasculitides, connective tissue diseases, and infections. We report a case of a 3-cm immunoglobulin G4-positive ITA aneurysm that was excised by a hybrid approach involving open ligation of the ITA origin and video-assisted thoracoscopic aneurysmectomy. This novel technique was able to acquire tissue for histopathologic diagnosis through a minimally invasive means.