Introduction

According to Chapell Hill  consensus  conference on  nomenclature  of systemic vasculitis (C. Jenette  Arthritis  and Reumatism-  1994,37:187-192) the definition of renal vasculitis is mainly based on size  of involved vessels.

1. Anca – associated vasculitis = small vessel arteritis (arterioles) characterized  by “pauci-immune” necrotizing crescentic  glomerolonephritis (Wegener ‘s granulomatosis microscopic  polyarteritis, renal limited form ). Medium size (interlobular) artery  involvement  could be present.
2. Polyarteritis nodosa and  Kawasaky  disease = necrotizing  inflammation of large  size arteries (arcuate and larger ) without necrotizing  extracapillary glomerulonephitis. Usually ANCA negative.

Independently of  definitions, it is a common experience that histological evidence of small vessel arteritis in ANCA-associated vasculitis is rare (about 15% of cases) and the evidence of medium to large size arteritis is extremely rare.
In a recent EUVAS MEPEX trial (Acute renal faillure) with histological review of 100 renal biopsies, the frequency of small vessel arteritis was 11% and medium to large size arteries 4% of cases (very rare).
There is a collaborative project  between Japan and EUVAS (financied by Healt Care Minister of Japan) to evaluate possible differences in ANCA-associated vasculitis in different Countries.

The first clear difference concerns the ratio of serum MPO-ANCA to PR3 ANCA that among Japanese is much higher than among European patients = 91% of the patients are MPO-ANCA positive. (S Fujimoto=incidence of ANCA-associated primary renal vasculits in the Miyazaki Prefecture; the first population based, retrospective, epidemiologic survey in Japan. Clin J Am Soc.Nephrol. 2006,1-1016).
Moreover the revision of certain number of biopsies (I am involved as EUVAS renal pathologist) seems to suggest a significantly higher frequency of large to medium size arteritis in the Japanese population. See micrographs below.
In preliminary data from the Shimoshizu National Hospital (Dr Kensuke Joh), on 28 cases of ANCA-associated vasculitis, 25% presented large to medium size arteritis.
All  these data, even though preliminary, could suggest possibile immunological and morphological differences between Japanese and European vasculitis, with possible differences in vasculitis in Americans. The data should serve as the basis of a discussion on possibile different genetic,enviromental factors and/or pathogenetic-morphogenetic mechanisms between the two populations.

Purpose of the study:
The research committee of RPS proposes a simple questionnaire to evaluate
            1)The frequency of small,medium and large size arteritis in  renal biopsies of ANCA - associated vasculitis(either active or chronic/sclerotic).
            2)The possible differences  among differnt Countries,in particolar with Japanese(and possibly other Far East Countries) population.
            3)The data of this qustionnaire could be the base for further evaluations of different genetic,evirenmental factors,pathogenetic-morphogenetic mechanisms and clinical features among different populations.

It is sufficient to review the reports ( the biopsies only in case of some doubt on report data ).

Micro 1- EUVAS-JAP - small vessel arteritis

Micro 2 - EUVAS-JAP - medium size vessel arteritis (interlobular)

Micro 3 - EUVAS-JAP - arquate arteritis