Fig 1.

Diagram depicting the usual distribution of vessel involvement by large vessel vasculitis, medium vessel vasculitis, and small vessel vasculitis. All 3 major categories of vasculitis can affect any size artery, although large vessel vasculitis most often affects large arteries. Medium vessel vasculitis predominantly affects medium arteries but small arteries may be affected. Small vessel vasculitis predominantly affects venules and capillaries. Immune complex small vessel vasculitis rarely affects arteries. Note that ANCA (antineutrophil cytoplasmic antibody) associated vasculitis affects a broader spectrum of vessels than immune complex vasculitis. Reproduced from reference 2 with permission.