Background
Urticarial vasculitis is an eruption of erythematous wheals that clinically resemble urticaria but histologically show changes of leukocytoclastic vasculitis. [1, 2] Urticarial vasculitis may be divided into normocomplementemic and hypocomplementemic variants. Both subsets can be associated with systemic symptoms (eg, angioedema, arthralgias, abdominal or chest pain, fever, pulmonary disease, renal disease, episcleritis, uveitis, and Raynaud phenomenon). The hypocomplementemic form more often is associated with systemic symptoms and has been linked to connective-tissue disease (ie, systemic lupus erythematosus [SLE], relapsing polychondritis). [3, 4, 5, 6, 7]
Pathophysiology
The pathophysiology of urticarial vasculitis is similar to other forms of cutaneous small vessel leukocytoclastic vasculitis. Urticarial vasculitis is a type III hypersensitivity reaction in which antigen-antibody complexes are deposited in the vascular lumina. This reaction results in complement activation and chemotaxis of neutrophils. These cells release various proteolytic enzymes, such as collagenase and elastase, resulting in damage to the vascular lumina. Some authors have speculated that eosinophils may be involved in the early stages of the vasculitic lesions. Patients with hypocomplementemic urticarial vasculitis are more likely to show autoantibodies to C1q and vascular endothelial cells. [8, 9] The presence of antineutrophilic cytoplasmic antibodies is rare. Many patients ultimately prove to have SLE. Other etiologies include drug reactions and parasitic infections. [10]
Etiology
The etiology of urticarial vasculitis has not been elucidated. Associated conditions are listed in History.
Epidemiology
Frequency
The exact frequency of urticarial vasculitis is not known in the United States or worldwide.
Leukocytoclastic vasculitis displayed an incidence of 45 cases per million population from a study conducted in Olmsted County, Minnesota. [11]
Previous studies varied in their definitions of the condition. However, when a study in the United Kingdom used consistent criteria restricted to patients diagnosed with vasculitis by biopsy and with urticarial lesions of more than 3 months duration, 2.1% of 1310 patients with urticaria were found to have urticarial vasculitis.
Sex
The male-to-female ratio for urticarial vasculitis is 1:2.
Age
The median age of urticarial vasculitis involvement is 43 years, with a range of 15-90 years. While urticarial vasculitis is primarily a disease of middle-aged adults, it can be seen in persons of any age.
Prognosis
Urticarial vasculitis tends to become a chronic condition and patients should be educated about its course. For most patients, this is a disease that affects the skin, with a minority of patients developing systemic complications.
Urticarial vasculitis carries a good prognosis, with most occurrences resolving in months to years. Urticarial vasculitis associated with hypocomplementemia is associated with a greater incidence of coexisting disease (ie, angioedema, connective-tissue disease [primarily SLE], chronic obstructive pulmonary disease). [12, 13] Mortality is rare. Some cohorts have demonstrated systemic involvement in roughly half of the patients, including musculoskeletal and ocular complications. [14]
Patient Education
Since urticarial vasculitis may be chronic, educate patients about its course. For patient education resources, see the Allergy Center and Hives and Angioedema.
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Raised erythematous wheals with postinflammatory hyperpigmentations suggest urticarial vasculitis.
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A low-power histologic image of urticarial vasculitis shows leukocytoclastic vasculitis with damage to the vessel wall and a neutrophilic infiltrate.
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A high-power view of the histology of urticarial vasculitis shows extensive fibrin deposition in the vessel walls. Surrounding the vessels is a mixed infiltrate predominately composed of neutrophils with leukocytoclasis.
