The last classification of vasculitis.

Systemic vasculitides are a group of diverse conditions characterized by inflammation of the blood vessels. To obtain homogeneity in clinical characteristics, prognosis, and response to treatment, patients with vasculitis should be classified into defined disease categories. Many classification schemes have been proposed, but the American College of Rheumatology (ACR) criteria and the Chapel Hill definitions for the systemic vasculitides are most widely used. The ACR criteria for classifying a patient with vasculitis within a specific disease entity are useful in clinical practice; but, in many cases, their application results in overlapping diagnoses, particularly in patients with small vessel vasculitis and classical polyarteritis nodosa (PAN). The Chapel Hill definitions cannot be used as classification criteria in clinical practice. A recently developed algorithm for the antineutrophil-cytoplasmic-autoantibodies-associated vasculitides and PAN, based both on the Chapel Hill definitions and the ACR criteria and in which clinical data and serological findings are included, proved useful for correctly classifying patients. The use of this algorithm together with the definitions for the large vessel vasculitides may result in a more unifying approach to the classification of the primary systemic vasculitides.