Systemic vasculitis involving the kidney: the nephropathologist's point of view.

Kidneys are often targets of systemic vasculitis (SVs), being affected in many different forms and representing a possible sentinel of an underlying multi-organ condition. Renal biopsy still remains the gold standard for the identification, characterization and classification of these diseases, solving complex differential diagnosis thanks to the combined application of light microscopy (LM), immunofluorescence (IF) and electron microscopy (EM). Due to the progressively increasing complexity of renal vasculitis classification systems (e.g. pauci-immune vs immune complex related forms), a clinico-pathological approach is mandatory and adequate technical and interpretative expertise in nephropathology is required to ensure the best standard of care for our patients. In this complex background, the present review aims at summarising the current knowledge and challenges in the world of renal vasculitis, unveiling the potential role of the introduction of digital pathology in this setting, from the creation of hub-spoke networks to the future application of artificial intelligence (AI) tools to aid in the diagnostic and scoring/classification process.

Systemic vasculitides and the role of multitechnique imaging in the diagnosis.

Vasculitis, a systemic disease characterised by inflammation of the blood vessels, remains challenging to diagnose and manage. Vessel size has been the basis for classifying systemic vasculitides. Imaging plays a vital role in diagnosing this challenging disease. This review article aims (a) to summarise up-to-date literature in this field, as well as include classification updates and (b) to review available imaging techniques, recent advances, and emphasis on imaging findings to diagnose large vessel vasculitides.

Are the 1990 American College of Rheumatology vasculitis classification criteria still valid?

Objectives: Advances in diagnostic techniques have led to better distinction between types of vasculitis, potentially affecting the utility of the 1990 ACR classification criteria for vasculitis. This study tested the performance of these criteria in a contemporary vasculitis cohort. Methods: The Diagnosis and Classification in Vasculitis Study provided detailed clinical, serological, pathological and radiological data from patients with primary systemic vasculitis and clinical context-specific comparator conditions. Fulfilment of six ACR criteria sets and their diagnostic performance was evaluated in patients with a given type of vasculitis and its comparator conditions. Results: Data from 1095 patients with primary systemic vasculitis and 415 with comparator conditions were available. For classification, sensitivities and specificities for ACR classification criteria were, respectively, 81.1% and 94.9% for GCA; 73.6% and 98.3% for Takayasu's arteritis; 65.6% and 88.7% for granulomatosis with polyangiitis; 57.0% and 99.8% for eosinophilic granulomatosis with polyangiitis; 40.6% and 87.8% for polyarteritis nodosa; 28.9% and 88.5% for microscopic polyangiitis; and 72.7% and 96.3% for IgA-vasculitis. Overall sensitivity was 67.1%. Of cases identified by their respective criteria, 16.9% also met criteria for other vasculitides. Diagnostic specificity ranged from 64.2 to 98.9%; overall, 113/415 comparators (27.2%) fulfilled at least one of the ACR classification criteria sets. Conclusion: Since publication of the ACR criteria for vasculitis, the sensitivity for each type of vasculitis, except GCA, has diminished, although the specificities have remained high, highlighting the need for updated classification criteria.

Vasculitis: do we know more to classify better?

The systemic vasculitides are a heterogeneous group of disorders characterized by the inflammation of blood vessels. The development and implementation of advanced diagnostic tests and genetic studies have resulted in substantial improvement in our understanding of vasculitis pathogenesis, resulting in the revision of the nomenclature and classification for vasculitis. Multicenter, collaborative studies are currently underway to develop improved diagnostic criteria. In this review, the major nomenclature and classification systems for vasculitides are summarized, with special emphasis on those emerging from the recent 2012 Chapel Hill Consensus Conference (CHCC).

Vasculitides with cutaneous expression in children: clinico-pathological correlations.

The most recent pediatric vasculitis classifications (EULAR/PRINTO/PRES) have proposed the use of an integration of clinical signs and symptoms, laboratory data, imaging and pathologic data. Pediatric vasculitis represent a peculiar clinical-diagnostic model, compared to the corresponding adult pathology chapter, and in particular, dermatopathologic aspects of these diseases identify more specific issues, made contingent by crucial variables such as duration of vasculitis lesion, site of the biopsy, proper biopsy depth, and possibility to correlate histopathological findings with immunopathological results. Possible additional diagnostic difficulties may arise from the fact that, in children, the same systemic disease, such as lupus erythematosus, may present with different clinical manifestations, with histopathological features of a precise type of vasculitis specific for that type of clinical manifestation. Examples are provided by hypocomplementemic urticarial vasculitis, cryoglobulinemic purpura, lymphocytic vasculitis of livedoid lesions. This paper describes the cutaneous histopathological findings of some vasculitis related pediatric diseases, be they pertaining to a systemic vasculitis with corresponding cutaneous vasculitis, to a systemic vasculitis with sporadic cutaneous vasculitic involvement, and to a systemic vasculitis without cutaneous vasculitic involvement. Type and level of histopathological vasculitic involvement, caliber of the vessel, type of vasculitis associated infiltrate, are likewise reliable integration in the complex diagnostic path of vasculitis in childhood. On the basis of these criteria dermatopathologists should be confident in identifying the type of the vasculitis and relate them to a specific pediatric disease.

[Systemic vasculitides: some debatable aspects of the problem].

A new nomenclature of systemic vasculitides (SV) and current approaches to their treatment have necessitated the discussion of some debatable questions on this condition. The paper gives the data of examining 325 patients with different forms of SV, followed up in the Interregional Consulting Center for SV patients, and the results of testing the American College of Rheumatology classification criteria for SV and the authors' criteria, by taking into account the International Chapel Hill Consensus Conference, USA (1994 and 2011) guidelines for CV nomenclature. It discusses the etiological factors and pathogenetic components of SV, morphological aspects, and relationships between the local and systemic forms of SV. The findings were compared with the data available in the literature. It is concluded that differentially diagnostic criteria for CV should be elaborated to specify the stage of the disease, the activity and use of adapted therapy regimens.

Validation of the classification criteria for cryoglobulinaemic vasculitis.

OBJECTIVE: The aim of this study was to validate the classification criteria for cryoglobulinaemic vasculitis (CV). METHODS: Twenty-three centres were involved. New patients with CV (group A) and controls, i.e. subjects with serum cryoglobulins but lacking CV based on the gold standard of clinical judgment (group B) and subjects without cryoglobulins but with clinical features that can be observed in the course of CV (group C), were studied. Positivity of serum cryoglobulins was necessary for CV classification. Sensitivity and specificity of the criteria were calculated by comparing group A vs group B. The group A vs group C comparison was done to demonstrate the possible diagnostic utility of the criteria. RESULTS: The study included 268 patients in group A, 182 controls in group B and 193 controls in group C (small vessel vasculitis, 51.8%). The questionnaire (at least 2/3 positive answers) showed 89.0% sensitivity and 93.4% specificity; the clinical item (at least 3/4 clinical involvement) showed 75.7% sensitivity and 89.0% specificity and the laboratory item (at least 2/3 laboratory data) showed 80.2% sensitivity and 62.4% specificity. The sensitivity and specificity of the classification criteria (at least 2/3 positive items) were 89.9% and 93.5%, respectively. The comparison of group A with group C demonstrated the clinical utility of the criteria in differentiating CV from CV mimickers. CONCLUSION: Classification criteria for CV were validated in a second, large, international study confirming good sensitivity and specificity in a complex systemic disease.

Clinicopathological characteristics and outcomes of pediatric patients with systemic small blood vessel vasculitis.

BACKGROUND: Systemic small blood vessel vasculitis (SSV) is uncommon among pediatric patients, and the predictive value of the new histopathological classification for SSV in terms of renal outcomes in these patients is unknown. METHODS: The study cohort comprised 38 pediatric patients and 285 adult patients with SSV who were treated in a medical center between 1993 and 2012. RESULTS: Children accounted for 11.8 % of all patients with SSV diagnosed during the study period. In contrast to the adult patients, the pediatric patients were predominantly female (73.7 vs. 51.9 %; P < 0.05). The prevalence of skin purpura was higher and pulmonary symptoms were less common among pediatric patients than among adult ones (36.8 vs. 13.7 %, P < 0.01 and 26.3 vs. 46.0 %, P < 0.05, respectively). Subtype was correlated with the baseline levels of serum creatinine and treatment response among patients with SSV and was found to have a tendency to predict end-stage renal disease (ESRD) among pediatric patients (hazard ratio 2.273, P < 0.01). The probability of progressing to ESRD was highest in pediatric patients with the sclerotic glomerulonephritis subtype, followed by the mixed, crescentic and focal glomerulonephritis subtypes (in descending order of probability) (P < 0.01). CONCLUSIONS: Estimated histopathological classification has a prognostic value for renal outcome and response to therapy in children with SSV.

[The current classification of systemic vasculitides].

Systemic vasculitides (SV) are severe multiorgan diseases whose early diagnosis and treatment can significantly improve prognosis. Improving the classification of SV may lead to a significant reduction in the likelihood of diagnostic errors. The presented paper deals with the results of the International Consensus Conference on the Nomenclature of SV (Chappel Hill, USA) in 2012. The nomenclature and definitions of the major forms of SV were revised and additional categories of vasculitis were included into the classification, by relying on the current trends in the practical use of terms, on the current ideas on the specific features of manifestations of diseases, and on achievements in studying the pathogenesis.

Systemic vasculitis: a critical digest of the recent literature.

Herewith we provide a critical digest of the recent literature on systemic vasculitis. In this manuscript, we reviewed all the articles published during the last 12 months on large-, medium- and small-vessel vasculitis and selected the most relevant studies regarding the epidemiology, pathogenesis and management of systemic vasculitis. In particular we focused the attention on giant cell arteritis, ANCA-associated vasculitis and cryoglobulinemia.

ACR/EULAR-endorsed study to develop Diagnostic and Classification Criteria for Vasculitis (DCVAS).

The systemic vasculitides are a group of uncommon diseases characterized by blood vessel inflammation. There are currently no diagnostic criteria for the primary systemic vasculitides and physicians must rely on experience and disease definitions. The absence of validated criteria can result in delays in making the correct diagnosis and starting appropriate therapy. With the increased understanding of the pathophysiology of vasculitis and newer diagnostic tests in widespread clinical use, it is an appropriate time for classification criteria for primary vasculitis to be revised. The Diagnostic and Classification Criteria for Vasculitis (DCVAS) study is a multinational observational study designed to develop and validate diagnostic criteria and to improve and validate classification criteria for primary systemic vasculitis. The analytic approach will be based on the traditional approach of vessel size for classification of vasculitis but will also incorporate detailed clinical data, evaluation of anti-neutrophil cytoplasm antibody diagnostic testing, biopsy and imaging data. The study is following the guidelines for the development of classification criteria established by the American College of Rheumatology and the European League against Rheumatism. The study will incorporate the use of pre-defined cases of each condition to reduce the inherent circularity when developing new classification criteria and will explore alternative approaches to deriving reference standards by creating data-driven classification algorithms. We anticipate recruiting >2,000 patients with primary systemic vasculitis and 1,500 patients with autoimmune diseases and other conditions that mimic vasculitis. As of June 2013, >100 medical centers across 31 countries in Asia, Australasia, Europe, North America, and South America were contributing data to the study. The DCVAS study provides a unique opportunity to increase generalizability and collate a large dataset on the occurrence, presentation, and outcome of vasculitis in different populations.

Epidemiology and clinical features of systemic vasculitis.

Different vasculitic syndromes present in different age groups. Immunoglobulin (Ig)A vasculitis and Kawasaki disease usually present in children whereas giant cell arteritis (GCA) and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis usually present in the middle aged/elderly. In Northern Europe, granulomatosis with polyangiitis (GPA; Wegener's) is commoner than microscopic polyangiitis (MPA) and MPA is more common than eosinophilic granulomatosis with polyangiitis (EPGA; Churg-Strauss syndrome). In Southern Europe, MPA is commoner than GPA and in Japan MPA is much more common than GPA. Major differences exist worldwide in ANCA specificity which are not entirely related to different phenotypes. GPA, like GCA, has a cyclical pattern of onset suggesting possible infection as an aetiological agent. International studies have given important clues to possible aetiology including silica dust and infection and genetic influences, as shown by the recently published genome-wide association study which revealed that single-nucleotide polymorphisms associate more strongly with ANCA than clinical syndromes. A brief description of the main clinical features of ANCA-associated vasculitis is also given.

Pulmonary complications of systemic vasculitides.

The pulmonary vasculitides are a heterogeneous group of diseases that often occur as a component of systemic vasculitic diseases. Most frequently, pulmonary vasculitis is observed in vasculitic syndromes that preferentially affect small vessels. Pulmonary involvement may develop because the lung has an extensive vascular and microvascular network. Sensitising antigens can easily reach the lung, and there are large numbers of vasoactive and activated immune cells in the lung. A diagnosis often can be made on the basis of clinical presentation and serologic studies, but biopsy of skin, nose, kidney, or lung may be necessary to ascertain the precise syndrome.

A cross-sectional study of the Birmingham Vasculitis Activity Score version 3 in systemic vasculitis.

OBJECTIVE: Assessment of disease activity in vasculitis can be achieved using the BVAS, a clinical checklist of relevant symptoms, signs and features of active disease. The aim of this study was to revalidate the BVAS version 3 (BVAS v. 3) in a cohort of patients with systemic vasculitis. METHODS: A total of 238 patients with vasculitis from seven countries in Europe were evaluated at a single time point. Spearman's correlation coefficients were calculated between BVAS v. 3 scores, vasculitis activity index (VAI), physician's global assessment (PGA), the physician's treatment decision, CRP and the vasculitis damage index (VDI) to demonstrate that the BVAS v. 3 measures disease activity. RESULTS: WG (63%), Churg-Strauss syndrome (9%) and microscopic polyangiitis (9%) were the most common diagnoses. The BVAS v. 3 showed convergent validity with the VAI [ρ = 0.82 (95% CI 0.77, 0.85)], PGA [ρ = 0.85 (95% CI 0.81, 0.88)] and the physician's treatment decision [ρ = 0.54 (95% CI 0.44, 0.62)]. There was little or no correlation between BVAS v. 3 and the CRP level [ρ = 0.18 (95% CI 0.05, 0.30)] or with the VDI [ρ = -0.10 (95% CI 0.22, 0.03)]. The inter-observer reliability was very high with an intra-class correlation coefficient (ICC) of 0.996 (95% CI 0.990, 0.998) for the total BVAS v. 3 score. CONCLUSION: The BVAS v. 3 has been evaluated in a large cohort of patients with vasculitis and the important properties of the tool revalidated. This study increases the utility of the BVAS v. 3 in different populations of patients with systemic vasculitis.

European League Against Rheumatism/European Vasculitis Study Group recommendations for the management of vasculitis.

PURPOSE OF REVIEW: To discuss the European League Against Rheumatism recommendations in the management of primary systemic vasculitis. RECENT FINDINGS: Important developments in the classification and treatment of systemic vasculitis have led the European League Against Rheumatism to publish recommendations in the diagnosis, treatment and monitoring of the small, medium and large-vessel vasculitides. These recommendations resulted from a combination of evidence from systematic analysis of selected studies and the experience of experts in vasculitis when data were not available. SUMMARY: The purpose of formulating clinical recommendations is to improve quality of care and guide the clinician inexperienced with vasculitis. Nevertheless, patients with vasculitis should be managed by a vasculitis expert whenever possible. As our understanding of this rare and complex group of diseases advances, novel therapeutic options are being developed.

EULAR points to consider in the development of classification and diagnostic criteria in systemic vasculitis.

OBJECTIVES: The systemic vasculitides are multiorgan diseases where early diagnosis and treatment can significantly improve outcomes. Robust nomenclature reduces diagnostic delay. However, key aspects of current nomenclature are widely perceived to be out of date, these include disease definitions, classification and diagnostic criteria. Therefore, the aim of the present work was to identify deficiencies and provide contemporary points to consider for the development of future definitions and criteria in systemic vasculitis. METHODS: The expert panel identified areas of concern within existing definitions/criteria. Consequently, a systematic literature review was undertaken looking to address these deficiencies and produce 'points to consider' in accordance with standardised European League Against Rheumatism (EULAR) operating procedures. In the absence of evidence, expert consensus was used. RESULTS: There was unanimous consensus for re-evaluating existing definitions and developing new criteria. A total of 17 points to consider were proposed, covering 6 main areas: biopsy, laboratory testing, diagnostic radiology, nosology, definitions and research agenda. Suggestions to improve and expand current definitions were described including the incorporation of anti-neutrophil cytoplasm antibody and aetiological factors, where known. The importance of biopsy in diagnosis and exclusion of mimics was highlighted, while equally emphasising its problems. Thus, the role of alternative diagnostic tools such as MRI, ultrasound and surrogate markers were also discussed. Finally, structures to develop future criteria were considered. CONCLUSIONS: Limitations in current classification criteria and definitions for vasculitis have been identified and suggestions provided for improvement. Additionally it is proposed that, in combination with the updated evidence, these should form the basis of future attempts to develop and validate revised criteria and definitions of vasculitis.

[Classification and therapy of vasculitis according to recommendations of the European League Against Rheumatism (EULAR)]. / Klassifikation und leitliniengerechte Empfehlungen zur Diagnose und Therapie von Vaskulitiden.

Vasculitis is still being classified according the criteria of the American College of Rheumatology and the Chapel Hill Consensus Conference Definitions. Diagnostic criteria are currently being established. The classification criteria are based on the size of the inflamed blood vessel (e.g. large vessel vasculitis with inflammation of the aorta and its branches), clinical symptoms and findings (such as cephalalgia in giant cell arteritis) and histological findings. In recent years a definition of disease stages and activity has been established and a number of controlled trials have been carried out in order to provide evidence-based stage and activity adapted therapy regimens. Recommendations for the management of vasculitis have been published in 2009 by EULAR (European League Against Rheumatism). This article gives a review of the classification of vasculitis and summarizes the current European guidelines on management.

Evolving concepts in classification of systemic vasculitis: where are we and what is the way forward?

The classification of the systemic vasculitides has been controversial for several decades. The Chapel Hill consensus Conference definitions originally developed in 1994, but revised and extended in 2012 are now widely accepted. The American College of Rheumatology (ACR) criteria were first published in 1990, are now generally accepted to be out of date and new criteria are needed. More recently the classical division of the ANCA vasculitides using clinical phenotype has come under scrutiny with evidence from epidemiological, genetic and outcome studies that perhaps these conditions should be classified on the basis of ANCA specificity into PR3-ANCA positive and MPO-ANCA positive groups. The traditional distinction between giant cell arteritis and Takayasu arteritis has been questioned and some recent studies of GCA have included patients with only extra-cranial disease. The Diagnostic and Classification Criteria of Vasculitis study (DCVAS) will provide new validated classification criteria for the systemic vasculitides.