ANCA-negative pauci-immune renal vasculitis: histology and outcome.
BACKGROUND
Pauci-immune renal vasculitis with focal glomerular necrosis and crescent formation is usually associated with anti-neutrophil cytoplasmic antibodies (ANCAs). However, ANCA's are absent in up to 10% of cases, which constitutes a rarely studied variant of renal vasculitis.


METHODS
This retrospective multicentre cohort study analyzed the presenting features, renal histology and outcome in 20 patients with pauci-immune crescentic necrotizing renal vasculitis in whom indirect immunofluorescence did not detect ANCA.


RESULTS
Renal histology revealed a high percentage of active glomerular lesions (50%), mainly cellular crescents, 28% of them with glomerular necrosis. Chronic tissue damage with glomerulosclerosis (21%) and diffuse interstitial fibrosis (40%) was already present at diagnosis, more prominent than in historical PR3-positive patients. Infiltrates of polymorphonuclear neutrophils in glomerular capillary loops were observed in 40% of all biopsies, mainly in necrotic lesions. The subsets of interstitially infiltrating leukocytes similar to ANCA-associated disease. Microscopic polyangiitis was diagnosed in 17 patients, Wegener's granulomatosis in two and renal-limited vasculitis in one. The patients median disease extent index (DEI) of 5 (range 4-11) reflected a systemic vasculitis. ANCA-negative vasculitis was not associated with infection or malignancy. Renal outcome was correlated to DEI (P = 0.032) and serum creatinine at diagnosis (P = 0.04). The mortality rate was high (35%) and closely related to age above 65 years at diagnosis (P = 0.014). Conclusions. The histological findings and prognosis in ANCA-negative renal vasculitis are comparable with those of ANCA-positive disease. Our data underline the importance of the exact diagnosis in an active vasculitic disease process even in the absence of ANCAs.
Eisenberger
Ute
U
University of Hospital, Department of Nephrology, Bern, Switzerland. ute.eisenberger@insel.ch
Fakhouri
Fadi
F
Vanhille
Philippe
P
Beaufils
Hélène
H
Mahr
Alfred
A
Guillevin
Loic
L
Lesavre
Philippe
P
Noël
Laure-Hélène
LH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood; D005260:Female; D005921:Glomerulonephritis / Q000097:blood / Q000150:complications / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D014657:Vasculitis / Q000097:blood / Q000150:complications / Q000473:pathology*
D019268:Antibodies, Antineutrophil Cytoplasmic; D003404:Creatinine