The use of plasma exchange (PLEX) as adjunct therapy in the initial management of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis remains to be discussed controversially in light of present evidence. In our Viewpoint we highlight scenarios where we think that physicians might still consider the use of PLEX, such as the most severe presentation forms including diffuse alveolar haemorrhage (DAH) with hypoxaemia and acute glomerulonephritis with significantly impaired kidney function. Recent sub-analyses of the PEXIVAS trial have focused on these patient populations and have provided outcomes of these patients. It became obvious that the mortality rates of those presenting with DAH were non-significantly lower and patients with severe GN show a trend of more pronounced estimated glomerular filtration rate (eGFR) recovery in the first weeks after PLEX. Notably, more patients reach a kidney function recovery as defined as eGFR increase ≥15 ml/min/1.73 m2 from baseline to week 52 when randomised to PLEX. These beneficial outcomes need to be balanced against the increased risk of serious infections and we recommend an individualized decision-making when considering addition of PLEX in the induction therapy.

The plenary session on "End organ damage and repair" at the 21st International Vasculitis Workshop Congress featured two lectures and three studies addressing the pathogenesis, diagnosis, and management of fibrosis in vasculitis. The studies presented at the session demonstrate the importance of cellular interplay in driving inflammation and fibrosis, like the B cell-fibroblast interactions in the aorta of giant cell arteritis patients and the potential fibrotic role of specific infiltrating macrophage subtypes in ANCA-associated glomerulonephritis. Moreover, organ damage, such as the presence of interstitial lung disease in ANCA-associated vasculitis, may impact on long-term outcome, and need a personalized treatment approach.

The session on 'Diagnosis and Classification of Vasculitis' featured six oral presentations covering various aspects of vasculitis diagnosis and classification. The application of the Ankara criteria for IgA vasculitis in adults was evaluated, finding that while the criteria showed good sensitivity, their specificity was insufficient, suggesting the need for refinement. A clustering approach to classifying ANCA-associated vasculitis (AAV) identified five distinct clusters, which improved prediction of disease outcomes. The performance of the new 2022 ACR/EULAR classification criteria was tested in a Spanish cohort, revealing reclassification of patients mainly based on ANCA subtype. The importance of standardized histopathological assessment in giant cell arteritis (GCA) was highlighted, while research on a tissue-mimicking phantom demonstrated its potential for ultrasound training. Finally, a study showed that prolonged [18F]FDG-PET/CT acquisition times improved diagnostic specificity for GCA. These findings underscore the need for continuous refinement of classification criteria and diagnostic techniques in vasculitis research and clinical practice.

Modern imaging including ultrasound, MRI and PET have all played a pivotal role in characterizing the distinctive musculotendinous pathology that is now recognized to define PMR. Each of these modalities offers inherent advantages and disadvantages relative to availability, cost and radiation exposure, although MRI and hybrid PET/CT are particularly capable of detecting highly sensitive and specific findings, and thus should be considered reliable tools for PMR diagnosis in everyday clinical practice. By contrast, the utility of imaging for monitoring disease activity and predicting long-term clinical outcomes represents areas of ongoing research interest. This narrative review outlines the invaluable contribution made by imaging to our current understanding of PMR as a distinct disease entity and evaluates the diagnostic performance of available modalities together with their future potential for disease activity assessment and prognostication.

Polyarteritis Nodosa (PAN), is the firstly described vasculitis and can be seen in paediatric and adult age. PAN has a heterozygous clinical picture including cutaneous, constitutional, musculoskeletal, gastrointestinal, and renal involvement. Description and splitting of other vasculitis, makes this medium vessel vasculitis, a very rare disease. Additionally, many subgroups of PAN have been defined and this effort let to move Hepatitis B virus-PAN to Vasculitis with probable aetiology. Anyhow, idiopathic PAN still exists and cohorts from various countries such as France, India, and Japan have been published. Rarity of PAN necessities global collaboration to highlight clinical features and genetics studies. GLOBAL-PAN is an ongoing collaborative project of EUVAS, VCRC and many national cohorts. This review covers the recent epidemiological data of PAN along with demographic and clinical characteristics of cohorts from all-over the world and GLOBAL-PAN.

The breakout session "Imaging in Disease Assessment" featured six abstracts on imaging advancements for vasculitis. Disease extent on cranial MRI and its association with visual complications in giant cell arteritis (GCA) was evaluated, introducing the Propensity for Enhancement for GCA (P EG) score to assess inflammation. Predictors of remission and relapse in chronic periaortitis were analyzed, suggesting the potential for tailored treatment approaches. A novel radiomic model using CT chest scans accurately predicted relapses in ANCA-associated vasculitis. FDG-PET for monitoring GCA in patients on tocilizumab demonstrated limited predictive value. Comparative assessments of Takayasu arteritis using the Takayasu Arteritis Disease Activity Index (TAIDAI) highlighted the need for standardized evaluations. Finally, a protocolized ultrasonography pathway for diagnosing large vessel vasculitis showed promising results, suggesting a combined ultrasound and second test approach, guided by CRP levels, as a gold standard. The session emphasized integrating imaging biomarkers with clinical assessments to improve disease management.

Systemic vasculitis can present with different manifestations, some of which require unique approaches. This session at the 21st International Vasculitis Workshop, examined six studies focused on "Management of Special Situations". In ANCA-associated vasculitis (AAV), two institutions reported on their experience with subglottic stenosis (SGS) from the standpoint of histologic features and management compared to patients with idiopathic SGS. In another study in AAV, morbidity and mortality in a recent patient cohort with the potentially life-threatening manifestation of diffuse alveolar hemorrhage was compared to a historical published cohort from the same institution. In Behçet disease, one study investigated gastrointestinal involvement, particularly the management and outcome of those who patients who required abdominal surgery. Pregnancy in vasculitis was the focus of two studies which examined the reproductive experiences and outcomes of women with diverse forms of vasculitis.

ANCA vasculitis is a systemic autoimmune small-vessel vasculitis characterized by autoantibodies targeting either MPO or PR3. While patients with ANCA vasculitis are successfully treated with broad-spectrum immunosuppression, these treatments often leave patients vulnerable to infections. Research in the field has made positive gains in regards to understanding autoantigen specificity and immune cell subset involvement in disease pathogenesis, relapse and remission. This review examines the state of the research field as it relates to possible new antigen- and cell-specific therapies in the vasculitis field. Potential avenues of therapeutic interest include selective elimination of autoreactive B cells by bispecific antibodies, tolerogenic liposomes or engineered T cells. Additionally, restoration of regulatory T-cell function is an attractive avenue to prolong remission of disease. Collectively, the field is well poised to begin investigating new and emerging cell therapies.

The search for targeted therapies and biomarkers for immune-mediated systemic vasculitis requires detailed understanding of molecular pathogenesis. Whilst candidate approaches have identified new opportunities for drug repurposing, they also miss novel approaches for targeting critical immunological or stromal pathways. On the other hand, bulk transcriptional profiling may fail to capture differences in cellular composition and, depending on the cell source profiled, miss important changes within inflamed vascular tissue. The past decade has seen major advances in both experimental techniques and analytical tools that enable multi-dimensional molecular profiling. Interrogation of the transcriptome and proteome is now possible at a single cell level, or at levels of spatial resolution within tissue that was previously unimaginable. As demonstrated during the presentations in the breakout session of the 21st International Vasculitis Workshop entitled Transcriptomic approaches to the study of systemic vasculitis, these techniques are revealing greater understanding of molecular underpinnings of the systemic vasculitides.

Kawasaki disease (kDa) has remained a medical mystery for the last five decades with a wide array of hypothesis about potential aetiological factors, that have never been confirmed. In this brief note, I revised the state-of-the-art for the so-called 'wind hypothesis', claiming that the nature and types of aerosols, particularly fine ones, can account for a central part of this research avenue and the relation to kDa. Characterizing their chemical nature, in particular of the composition in trace elements, as well as their biological components (bacteria, fungi and viruses) stands up today as the most promising avenue towards constraining the range of environmental factors modulating or being responsible for this long-debated disease. Understanding kDa thanks to its unprecedented epidemiological record in Japan, going back to before the 1970s, may also improve our understanding of other similar vasculitis and rheumatic diseases.

The 21st International Vasculitis Workshop, held in Barcelona, Spain, from April 7 to 10, 2024, highlighted advances in pediatric vasculitis, focusing on a holistic, multidisciplinary approach. Common childhood vasculitides, including IgA Vasculitis (IgAV) and Kawasaki Disease (KD), were discussed. The Ankara 2008 criteria for IgAV, endorsed by EULAR and PReS, were evaluated for their performance in adults, showing high sensitivity but necessitating further refinement for improved specificity. Studies on genetic associations, such as Human Leukocyte Antigen (HLA) polymorphisms in IgAV, and biomarkers like S100A8/A9, HMGB1, and RAGE, were presented. Kawasaki disease research included novel anti-apolipoprotein A-2 antibodies, showing promise in reducing coronary arteritis. Monogenic vasculitides, such as deficiency of ADA2, were addressed with new consensus-driven recommendations. The workshop underscored the importance of continued research and tailored therapeutic strategies to improve outcomes in pediatric vasculitis, paving the way for advancements in diagnosis, management, and understanding of these complex diseases.

The steps leading to key pathogenetic aspect of ANCA-associated vasculitis, such as lung nodules in granulomatosis with polyangiitis (GPA), onset of glomerulonephritis (GN) in experimental myeloperoxidase (MPO)-ANCA models and the implications of carrying staphylococcal superantigens, such as toxic shock syndrome toxin-1 (tsst-1), in GPA remain to be elucidated. The session 'Cellular and molecular mechanisms of disease (II)' was devoted to close some of these knowledge gaps and underlined that research in ANCA-associated vasculitis leads to more granular understanding of these complex diseases. Here, we present an overview of this session at a glance.

Immunoglobulin G4-related disease (IgG4-RD) is a systemic immune-mediated fibroinflammatory disease that is believed but not confirmed to have an autoimmune origin. Since its discovery nearly two decades ago, our understanding of its pathophysiology and clinical manifestations has grown substantially. Early diagnosis and treatment of this elusive disease can prevent substantial organ damage from end-stage fibrosis. This underscores the importance of prompt recognition, full characterization, and astute management. The American College of Rheumatology/European League Against Rheumatism Classification Criteria provide a framework for approaching the diagnosis of IgG4-RD even though they were not intended for diagnostic purposes. The approach to diagnosis involves recognizing the typical disease manifestations and incorporating clinical, radiological, serological, and histopathological information. The exclusion of disease mimickers, particularly malignancy and other inflammatory conditions, is essential. Both glucocorticoids and B cell depletion are effective at inducing remission in IgG4-RD in most patients. The optimal approach to the use of these agents is now being defined in clinical trials.

Pregnancy may have a beneficial effect on disease activity in rheumatoid arthritis (RA) but the evidence is more conflicting in spondyloarthritis (SpA). The aim of this study was to analyse disease activity and relapse during pregnancy in women with RA and SpA.

Gout is the most common form of inflammatory arthritis in adults worldwide. There has been a steady increase in prevalence, which varies across different geographic areas and is high in the Indigenous (First Nations) peoples of the Pacific region. Palaeo-archaeological studies demonstrate that gout was present in the Pacific region prior to European colonization, which is suggestive of genetic predisposition. Genetic risk factors, including population-specific genetic variants and genetic variants shared across populations, particularly those influencing urate transporters, have been identified in Indigenous peoples of the Pacific that partly explain the earlier age of onset of gout. Indigenous peoples of the Pacific experience severe gout, with frequent flares, high hospitalization rates and tophaceous gout, all aggravated by socio-cultural factors. Despite a specific need for effective gout management, Indigenous peoples of the Pacific are under-represented in gout research and inequities in care continue. Indigenous peoples-led, holistic gout management programmes are systematically and urgently required in this region, where gout is a major public health issue. Importantly, a foundation of cultural safety is necessary to underpin such programmes.

To assess the phenotypic characteristics of the patients carrying variants of uncertain significance (VUS) in the Mediterranean fever (MEFV) gene.