|
|
 |
 |
| |
 Printable version |
Vasculitides in childhood : an introduction |
Médecine thérapeutique / Pédiatrie. Volume 14, Number 5-6, 340-8, Septembre-Décembre 2011, Dossier
|
 Résumé
Texte intégral
|
Author(s) : Jean-Louis Stéphan, Etienne Merlin |
Summary : <\;p>Primary systemic vasculitis (PSV) of the young refers to a heterogeneous group of disorders that are characterised by inflammatory destruction of blood vessels with resultant tissue ischaemia and necrosis. The classification of vasculitides has been controversial since the first attempts more than a century ago due, in large part, to a general lack of understanding regarding the mechanisms of disease. The proposed criteria for Henoch-Schönlein purpura (HSP), polyarteritis nodosa, Wegener granulomatosis &\; Takayasu have been validated and updated by an international consensus committee in conference in Ankara in 2008.<\;/p><\;p>One of the primary issues in management of vasculitis is the difficulty in establishing a diagnosis. Early in the course of disease, findings are often non-specific and reflect systemic inflammation (e.g., fever, weight loss, perplexing rashes). As vessel damage progresses, more characteristic abnormalities of vascular injury will accumulate including vascular compromise, biochemical markers of vascular injury (e.g., elevation of von Willebrand factor antigen) and distinctive auto-antibodies (e.g., ANCA). Pathognomonic changes (e.g., infarct, aneurysm, pulmonary or gastrointestinal haemorrhage) commonly reflect severe and often irreversible tissue injury.<\;/p><\;p>Initial evaluation of patients with suspected vasculitis typically includes a complete blood count, measures of acute-phase reactants and screening liver and renal function studies. With the exception of Kawasaki Disease, the reference standard for diagnosis of vasculitis remains histopathological demonstration of vascular injury on tissue biopsy, seldom needed for HSP.<\;/p><\;p>The pathogenesis of different types of systemic vasculitis negative for ANCA and involving small or medium-sized vessels is not very well documented. During Henoch-Schönlein purpura, histological lesions may result from the deposition of immune complexes formed from pathogens and from antibodies responsible for the activation of the classic complement pathway and for recruitment of polymorphonuclear neutrophils. The pathogenic role of ANCA has been well documented
in vivo, since in a myeloperoxydase (MPO) knockout mouse model immunized with MPO, passive transfer of anti-MPO ANCA is sufficient to induce the disease.
In vitro, in the mouse and in the human, anti-proteinase 3 ANCA are able to activate neutrophils primed with TNF-alpha and contribute to vasculitis lesions.<\;/p> |
Keywords : vasculitis, classification |
|
