Classification
Vasculitis can be classified by the cause, the location, the type of vessel or the size of vessel.
- Underlying cause. For example, the cause of syphilitic aortitis is infectious (aortitis simply refers to arteritis of the aorta, which is an artery.) However, the cause of many forms of vasculitis are poorly understood. There is usually an immune component, but the trigger is often not identified. In these cases, the antibody found is sometimes used in classification, as in ANCA-associated vasculitides.
- Location of the affected vessels. For example, ICD-10 classifies "vasculitis limited to skin" with skin conditions (under "L"), and "necrotizing vasculopathies" with musculoskeletal system and connective tissue conditions (under "M"). Arteritis/phlebitis on their own are classified with circulatory conditions (under "I").
- Type or size of the blood vessels that they predominantly affect. Apart from the arteritis/phlebitis distinction mentioned above, vasculitis is often classified by the caliber of the vessel affected. However, there can be some variation in the size of the vessels affected.
According to the size of the vessel affected, vasculitis can be classified into:
- Large vessel:Polymyalgia rheumatica, Takayasu's arteritis, Temporal arteritis
- Medium vessel: Buerger's disease, Cutaneous vasculitis, Kawasaki disease, Polyarteritis nodosa
- Small vessel: Behçet's syndrome, Churg–Strauss syndrome, cutaneous vasculitis, Henoch–Schönlein purpura, Microscopic polyangiitis, Wegener's granulomatosis
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