Kidney involvement in medium- and large-vessel vasculitis.

Medium- and large-vessel vasculitides (MVV and LVV, respectively) comprise a heterogeneous group of disorders whose common denominator is the inflammatory involvement of vessels of medium and large size. This disease spectrum includes giant-cell arteritis and Takayasu's arteritis, which typically affect the aorta and its main branches, and Kawasaki's disease and polyarteritis nodosa, which involve medium-sized arteries. Chronic periaortitis, characterized by a perivascular fibro-inflammatory reaction affecting the abdominal aorta and the periaortic tissue, frequently has a systemic distribution, involving other segments of the aorta and its major branches, and could thus be included in this group. Unlike small-vessel vasculitides, MVV and LVV do not cause glomerulonephritis, although glomerular immune-mediated lesions and tubulo-interstitial nephritis occur with varying frequency. However, MVV and LVV can often involve the renal artery and its branches, causing a wide array of lesions that range from renal artery stenosis to intra-renal vasculitis causing renal ischaemia/infarction, microaneurysms and haemorrhage. This review focuses on renal involvement in MVV and LVV and underlines why renal abnormalities in these syndromes should not be overlooked.