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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