Renal vasculitis.

The term 'vasculitides' encompasses a group of inflammatory disorders which may affect the kidney by damaging its blood supply. Although the kidney may be affected by many types of systemic vasculitis, renal involvement is particularly frequent in some forms of systemic necrotizing vasculitis which are considered primary, such as Wegener's granulomatosis and microscopic polyarteritis, including its 'renal-limited' variant. Renal vasculitis can occur at any age, but is seen particularly frequently in middle-aged and elderly subjects, in whom clinical presentation and prognosis are significantly worse. In addition to the specific problems related to age, this review focuses on a few aspects that are still the subjects of debate: classification, the role of ANCA, renal pathology and the treatment of renal vasculitis.