Approximately 10% of systemic vasculitis patients test
negative for ANCA( PR3 or MPO). This group has been studied only infrequently. It appears that evidence suggests that ANCA
negative disease is more renal limited and more severe to the kidney. Some data
suggesting that anti
endothelial antibodies might be associated with ANCA negative vasculitis.
Hedger et al.
investigated over 30 patients with ANCA-negative rapidly progressive
glomerulonepritis and found that they had fewer respiratory findings compared
to ANCA positive patients. Eisenberger et al.
have identified 20 cases with ANCA negative vasculitis. The renal histology
revealed a high percentage of active glomerular lesions (50%), mainly cellular
crescents, whereas only 28% of them had glomerular necrosis. Chronic tissue
damage with glomerulosclerosis (21%) and diffuse interstitial fibrosis (40%)
were already present at diagnosis, more prominent than in historical ANCA
positive patients. Age over 65 was found
to be predictor of mortality in this study.
In another study, they
found that the level of urinary protein and the prevalence of nephrotic
syndrome were significantly higher in ANCA-negative patients than that in
ANCA-positive patients. The renal pathology was more severe in ANCA negative
groups and the renal survival was poorer as per prior studies. Treatment has been focused on using combo
therapy of either cytoxan+steroids or MMF+steroids.
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