
Patients with urticarial vasculitis have signs that indicate a mix of dermal oedema
(urticarial wheals) and small-vessel cutaneous vasculitis (palpable purpura). The smooth,
erythematous papules (wheals) are uncomfortable (tender or burn) but may also itch;
individual wheals last up to 72h, and wheals resolve, leaving bruising. Some patients
have angio-oedema-like lesions. Simple urticaria is itchy; individual wheals last around
24h, and wheals fade to leave normal skin. Also see Schnitzler syndrome.
Associations
• Connective tissue diseases: some patients with low complement levels have anti-C1q
antibodies and overlapping features with SLE, including pleuritis, glomerulonephritis,
eye symptoms, and positive ANAs.
• Serum sickness (10 days after the administration of drugs or vaccines).
• Infections, including hepatitis C virus (HCV) infection.
• Haematological malignancies; IgM or IgG gammopathy.
What should I ask?
• Document the evolution of individual lesions. If the duration is uncertain, ask the
patient to draw around fresh lesions, and note how long they last.
• Does the wheal blanch, or is it purpuric? patients may have a mix of urticarial and
purpuric lesions, as well as angio-oedema-like swellings. Is there residual bruising when
lesions resolve?
• Ask about musculoskeletal symptoms (common: 50–75% of patients) or GI symptoms
(less common).
What should I do?
• Search for an underlying cause, and check FBC (anaemia is common), ESR (often
raised), complement (low complement, detected in 18% of patients, suggests an
underlying systemic disease), and autoantibodies, including anti-C1q antibodies.
• Exclude systemic vasculitis.
• Take a skin biopsy from a purpuric lesion to confirm the presence of a leukocytoclastic
vasculitis.
Treatment options:
• Antihistamines.
• Dapsone, colchicine, or hydroxychloroquine.
• NSAIds.
• Severe disease: prednisolone or steroid-sparing agents (azathioprine,cyclophosphamide,
ciclosporin, mycophenolate mofetil).