Urticarial vasculitis, recognise, biopsy, stratify by complement

Separates urticarial vasculitis from chronic spontaneous urticaria, the wheals last longer than a day, burn rather than itch, and heal with bruising, confirms it on skin biopsy, then stratifies by complement. Normal complement is usually skin-limited; low complement flags systemic disease and, when the Schwartz criteria are met, hypocomplementemic urticarial vasculitis syndrome (HUVS), which overlaps heavily with lupus.

Evidence tier: Expert consensus. Reflects expert-consensus criteria, not a prospectively validated instrument. Apply clinical judgment and local policy.

Decision points

  • Do the wheals behave like urticaria, or like vasculitis?
  • Is complement low?
  • Are the HUVS (Schwartz) criteria met?

Do-not-miss pitfalls

  • Urticarial vasculitis is the diagnosis behind a meaningful share of "antihistamine-refractory chronic urticaria." The tell is the individual wheal: >24 hours in one place, painful or burning rather than itchy, and healing with a bruise or a stain. Circle a lesion and look the next day.
  • The diagnosis is histologic. A compatible history is not enough, biopsy a fresh (<24-48 h) lesion for leukocytoclastic vasculitis before committing anyone to immunosuppression.
  • Complement is the prognostic split, so always send C3, C4, C1q, and CH50. Normal complement is usually skin-limited; low complement flags systemic disease.
  • HUVS overlaps heavily with lupus, send ANA and full SLE serologies. Many HUVS patients are ANA-positive and a large fraction develop SLE, so the two diagnoses must be actively distinguished rather than assumed separate.
  • In HUVS, LUNG involvement (COPD/emphysema) drives prognosis and is easy to overlook in a patient who presents with a rash. Do not stop the work-up at the skin and joints.
  • Antihistamines target the wrong mediator here. Symptom relief and disease control come from anti-inflammatory and immunosuppressive agents (colchicine, dapsone, hydroxychloroquine; then corticosteroids and steroid-sparing immunosuppressants), matched to how much systemic disease is present.
  • Screen for a secondary cause in every case: drug, infection (including hepatitis), connective-tissue disease, IgM gammopathy/Schnitzler, and malignancy, urticarial vasculitis can be the presenting sign of another disease.

Evidence & citations

  1. Bonnekoh H, Jelden-Thurm J, Butze M, et al. Urticarial Vasculitis Differs From Chronic Spontaneous Urticaria in Time Course, Clinical Features, and Response to Treatment. J Allergy Clin Immunol Pract. 2023;11(9):2900-2910. PMID 37364667
  2. Schwartz HR, McDuffie FC, Black LF, et al. Hypocomplementemic urticarial vasculitis: association with chronic obstructive pulmonary disease. Mayo Clin Proc. 1982;57(4):231-238. PMID 7040825
  3. Kolkhir P, Grakhova M, Bonnekoh H, et al. Treatment of urticarial vasculitis: A systematic review. J Allergy Clin Immunol. 2019;143(2):458-466. PMID 30268388

Clinician decision support. Verify against the cited source. Not a substitute for clinical judgment. 100% on-device; no patient data is stored or transmitted.