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Synonyms: leukocytoclastic angiitis/vasculitis, cutaneous small-vessel necrotizing
vasculitis, allergic vasculitis, hypersensitivity angiitis.

This is the commonest vasculitis affecting the skin. The vasculitic lesions in idiopathic
small-vessel cutaneous vasculitis are identical to those in a small-vessel cutaneous
vasculitis occurring as part of a systemic disease associated with circulating immune
complexes. Idiopathic small-vessel cutaneous vasculitis confined to the skin usually
resolves within a few weeks or months. Ten percent have recurrent disease lasting
months or years.

Related factors:
• Explore the distribution and evolution of the rash.
• Search for an underlying cause.
• Enquire about symptoms such as orogenital ulcers, dry eyes, dry mouth, GI symptoms,
myalgia, arthralgia, or joint swelling.

Symptoms :
1. Distribution:
• Vasculitis involves dependent areas such as the leg, sites of trauma, pressure sites
(elbows, sacrum, waist band), or cool skin (tip of the nose, ears, fingers).

2. Morphology:
• Is the rash purpuric? purpura, unlike erythema, does not blanch with light pressure.
• Are the spots flat or raised (palpable)? palpable purpura is the hallmark of small-vessel
cutaneous vasculitis. Flat (macular) purpuric lesions are associated with non-
inflammatory pathology.
• How does the rash evolve? In small-vessel cutaneous vasculitis, small round or oval
erythematous macules rapidly become raised and purpuric. Papules may coalesce into
larger polycyclic or annular lesions.
• Are there blisters, pustules, or ulcers secondary to inflammation?
• What is left? Vasculitis fades gradually over 3 or 4 weeks, leaving macular
pigmentation (haemosiderin) or atrophic scars.

3. Note the position of leg ulcers, and check for signs of stasis or arterial disease. Is there
purpura around the edge of the ulcer (a feature of some vasculitic ulcers)?

4. Look for livedo reticularis, retiform purpura, or ulcerated nodules indicating a
necrotizing vasculitis affecting deeper vessels or an occlusive vasculopathy, e.g.
cholesterol emboli.

5. Is there evidence of a systemic disease.

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