1. Abhijeet Gaike
2. Anisha Chougale
(1. Student, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic.
2. Student, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic.)
Abstract
The term “systemic vasculitis” refers to a broad category of conditions marked by blood vessel wall inflammation and necrosis, resulting in tissue ischemia and involvement of multiple organs. Unique patterns of vascular involvement, clinical symptoms, and immunopathogenesis have been observed in KD, EGPA, MPA, Buerger’s disease, and Behçet’s disease. Recent developments, especially in ANCA-associated vasculitis and EGPA, have enhanced our knowledge of immunological pathways, improved diagnostic instruments, and revised treatment recommendations. Long-term vascular problems do occur, and many diagnoses are delayed, particularly in the case of uncommon or unusual presentations. This thorough review covers definitions, pathophysiology, clinical characteristics, diagnostics, and treatments, and considers the most recent findings and changing methods in the treatment of vasculitis.
Keywords: Systemic vasculitis, Vasculitis classification, Small-vessel vasculitis.
Introduction
Inflammation of blood arteries, which can affect vessels of any size (large, medium, small, or variable), causes structural damage, luminal narrowing, aneurysm formation, thrombosis, and downstream tissue ischemia in the diverse group of illnesses known as vasculitis.
Autoimmune mechanisms, immune complex deposition, damage caused by antineutrophil cytoplasmic antibodies (ANCA), or exogenous triggers such as infections or toxins could all contribute to their genesis. Systemic vasculitis frequently presents diagnostic difficulties, resulting in delays in diagnosis and treatment, as clinical symptoms vary greatly depending on the organs involved.
Recent developments in immunology and multicenter registry data have greatly advanced our understanding of vasculitis, leading to more accurate classification, better diagnostic and monitoring tools, and revised therapeutic approaches. Nevertheless, rare forms remain underappreciated. This review covers five clinically significant vasculitides—KD, EGPA, MPA, Buerger’s disease, and Behçet’s disease— and summarizes established knowledge and incorporates recent findings pertinent to illness awareness, diagnosis, and treatment.
Kawasaki Disease (KD)
Definition and Epidemiology:
Children under the age of five are the principal victims of KD, an acute, self-limited medium-vessel vasculitis that continues to be a major contributor to acquired heart disease in children in developed countries.
Pathogenesis & New Insights
Although the exact cause of KD remains unknown, recent studies have improved our understanding of its immunopathogenesis. According to a 2024 review, endothelial dysfunction, autoantibodies, increased inflammatory cytokines, and persistent vascular inflammation are important factors in the development of coronary artery lesions.
Furthermore, the immunological mechanisms underlying cardiovascular problems have been clarified using mouse models of KD vasculitis, opening the door to new therapeutic approaches outside the conventional immunoglobulin/aspirin regimen.
Additionally, there has been epidemiological interest: a 2025 retrospective cohort study (patients 2010–2023) revealed that approximately 38.9% of 104 patients with KD developed coronary aneurysms despite receiving standard therapy (IVIG + aspirin), highlighting the ongoing risk even with prompt treatment.
Infectious triggers are still being investigated in case studies. For example, a recent report from 2025 detailed a 9-year-old boy who experienced a “Kawasaki-like” sickness two weeks after being verified to have contracted the Chikungunya virus, suggesting that older children may experience virus-induced vasculitic reactions.
Clinical & Diagnostic Implications
The need for long-term cardiac follow-up after acute illness is reinforced by the persistence of coronary problems, even in cured patients. Clinicians should be vigilant for unusual presentations, particularly in post-infectious settings, given the possible role of viral triggers in causing KD-like syndromes.
Treatment & Future Directions
Ongoing research into immunopathogenesis may result in adjuvant medicines or alternative regimens, especially for individuals who are resistant to standard therapy, even though high-dose IVIG and aspirin remain the cornerstones.
Eosinophilic Granulomatosis with Polyangiitis (EGPA)
Definition & Clinical Features
Asthma, eosinophilia, and necrotizing granulomatous inflammation are the hallmarks of EGPA, a small-to-medium vessel ANCA-associated (often p-ANCA/MPO) vasculitis. Numerous organs are affected, including the heart, gastrointestinal tract, skin, nerves, and lungs.
Recent Developments: New Consensus & Diagnostics
The “Multidisciplinary Expert Consensus on the Diagnosis and Treatment of EGPA (2025 Edition)”—the first such thorough update since 2018—was published in 2025. Thirteen suggestions addressing diagnosis, severity evaluation, induction and maintenance therapy, and follow-up are outlined in this consensus, which incorporates the latest data on pathophysiology, diagnostic criteria, and treatment.
Notably, the consensus highlights that patients with peripheral eosinophilia (≥1 × 10^9/L), chronic rhinosinusitis (with or without nasal polyps), asthma (especially adult-onset), and symptoms of end-organ involvement should be investigated for EGPA (ANCA test, biopsy where appropriate).
Novel Monitoring Tools: Microvascular Assessment
Nailfold videocapillaroscopy (NVC), a non-invasive microvascular imaging method, was assessed in 29 patients with EGPA in a 2025 study published in the Journal of Clinical Medicine. Microcirculatory irregularities were noted by the authors, indicating that NVC may be useful as an additional technique to identify microvascular involvement and track disease activity.
Case Illustration: Cardiac & Hematologic Involvement
EGPA can present with uncommon but dangerous systemic consequences beyond characteristic asthma and vasculitis, requiring widespread diagnostic attention, as demonstrated by a recent 2025 case report that described a patient with EGPA with concurrent myocarditis and autoimmune hemolytic anemia.
Treatment & Management Trends
According to the 2025 consensus, treatment should be customized based on the activity level and severity of the illness. High-dose corticosteroids combined with cyclophosphamide or rituximab are recommended for severe active EGPA, whereas corticosteroids combined with the biologic drug mepolizumab are preferred for non-severe illness. Methotrexate, azathioprine, and mepolizumab are alternative maintenance therapies. A move toward precision medicine is reflected in this stratified strategy, which strikes a balance between long-term safety, quality of life, and the effectiveness of immunosuppressants.
Microscopic Polyangiitis (MPA) / ANCA-Associated Vasculitis (AAV)
Definition & Classification Challenges
Necrotizing vasculitis without granulomatous inflammation is the hallmark of MPA, a small-vessel ANCA-associated vasculitis (frequently p-ANCA/MPO) that usually affects the kidneys (rapidly progressive glomerulonephritis), lungs (alveolar hemorrhage), skin, and other organs. Nevertheless, a 2024 data-driven analysis of approximately 3,900 AAV patients from various European registries found five different clinical clusters, going beyond the traditional division of AAV into MPA and GPA. This suggests a more complex, possibly biologically significant subclassification of AAV that could affect treatment choices and prognosis.
Additionally, the British Society for Rheumatology (BSR) revised the treatment and management recommendations for AAV (including MPA and EGPA) in a 2025 guideline update that incorporated expert consensus and new findings.
Lung Involvement: Recent Observations
A 2025 study from Central Asia highlighted the common but inconsistent pulmonary involvement in MPA/AAV by describing the particular characteristics of lung injury in ANCA-associated vasculitis. These results highlight the necessity of a thorough pulmonary evaluation in cases of suspected AAV.
Clinical & Management Implications
The identification of unique AAV clusters suggests that a “one-size-fits-all” approach might not be optimal. Rather, adjusting treatment according to illness severity and cluster (e.g., mainly renal vs. pulmonary vs. systemic inflammation) may enhance results. This shift toward customized therapy is reflected in the new BSR guidelines for PsA.
Buerger’s Disease (Thromboangiitis Obliterans)
There are still few studies that explicitly update Buerger’s disease, despite the majority of new literature being on large-vessel vasculitis and AAV. Numerous complex and recently identified vasculitis syndromes (such as monogenic or autoinflammatory) are emerging, which may have characteristics in common with classical Buerger’s disease but differ from it, according to a 2024 review of rare primary vasculitis.
This highlights the need for reevaluation and more thorough diagnostic investigation (genetic testing, vascular imaging, immunologic profiling), as some patients that were previously classified as having Buerger’s disease may actually reflect other, possibly genetically driven vasculitis syndromes. As a result, the traditional paradigm of “young smoker male with distal limb ischemia” should be upheld, but with increased awareness of possible mimics and consideration for sophisticated diagnostics in cases of atypical or refractory presentations.
Behçet’s Disease (BD)
BD may be more common than previously believed, according to a recent analysis of large vasculitis registries (e.g., data from 2007–2021 in Germany), especially when data collection, improved diagnoses, and more clinician knowledge are considered.
A 2024 retrospective study from a tertiary center highlighted the disparities in presentation and prognosis between pediatric and adult-onset BD by describing the clinical, laboratory, and demographic features of children with disease onset before maturity.
Furthermore, several uncommon monogenic autoinflammatory illnesses may phenotypically overlap with BD or other vasculitides, according to genetic and monogenic research (covered in pediatric vasculitis reviews). This supports the idea of “genetically mediated vasculitis-like syndromes.” These findings highlight the importance of improved illness awareness, early rheumatology referrals, and genetic workups in unusual or familial cases.
Broader Trends, Challenges, and Future Directions
Epidemiology & Recognition
According to a recent epidemiological assessment, the apparent incidence of systemic vasculitis (including BD, AAV, and large-vessel vasculitis) has increased due to improved detection and diagnostic techniques, suggesting that these illnesses may be underdiagnosed in many areas. However, a direct comparison of incidence and prevalence statistics is hampered by regional variations in diagnostic procedures and the classification criteria.
Diagnostic Innovations & Precision Medicine
The application of cutting-edge techniques, such as data-driven disease clustering (in AAV) and microvascular imaging (e.g., nailfold videocapillaroscopy in EGPA), highlights a move toward precision medicine, which aims to categorize vasculitis not only by conventional clinical categories but also by underlying pathophysiology and risk profiles. Furthermore, new consensus guidelines (such as the 2025 BSR AAV guidelines and the 2025 EGPA consensus) demonstrate how changing evidence influences the algorithms for diagnosis and therapy.
Persistent Challenges
A significant percentage of patients continue to experience vascular problems, even with appropriate care, such as in KD. Due to poor awareness, a variety of manifestations, and restricted access to modern tests or specialized care, rare vasculitides are still underdiagnosed and frequently cause delays in diagnosis. For many illnesses, there is still a dearth of long-term follow-up data, particularly in children transitioning to adulthood.
Future Perspectives
Novel treatment targets may be identified by further investigation into immunopathogenesis, including genetic and molecular factors. The increasing identification of monogenic/autoinflammatory vasculitis-like disorders raises the possibility that “vasculitis” will be separated into more specific disease entities. As demonstrated by the most recent EGPA and AAV guidelines, the application of personalized medicine involves stratified treatment protocols based on disease severity, activity, organ involvement, biomarker profiles, and the risk of relapse.
creation and verification of non-invasive monitoring instruments (such as molecular biomarkers, sophisticated imaging, and NVC) to evaluate vascular involvement and direct treatments. To ascertain the true incidence, prevalence, and consequences, more thorough epidemiological studies should be conducted worldwide, particularly in underrepresented areas. This will help with resource allocation, awareness campaigns, and early diagnosis.
Conclusion
Although long-known conditions such as KD, EGPA, MPA, Buerger’s disease, and Behçet’s disease have well-characterized clinical frameworks, systemic vasculitis remains complex and evolving. Recent research (2023–2025) has improved diagnostic and classification techniques, advanced therapeutic recommendations, and increased our understanding of the disease mechanisms. However, problems still exist, including underdiagnosis in many regions of the world, delayed diagnosis, and vascular consequences despite treatment.
Continued efforts are required to enhance patient outcomes, including raising clinician knowledge, implementing updated consensus guidelines, implementing innovative diagnostic and monitoring technologies, and conducting more in-depth research on etiology and precision medicine.
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