By Gary M. White, MD
This patient had urticarial plaques that left annular purpuric rings.
Urticarial vasculitis (UV) may be defined as urticarial lesions that histologically show vasculitis. In contrast to classic urticaria, UV lesions persist at the same location for more than 24 hours.
Urticarial vasculitis is not a specific disease but instead a clinical finding. A search for a cause of the vasculitis should be undertaken. The most common associated condition is systemic lupus erythematosus. Other possibilities include Sjögren's syndrome, serum sickness, viral infections (e.g. hepatitis C, infectious mononucleosis), mixed cryoglobulins, a monoclonal IgM gammopathy (e.g. Schnitzler syndrome), IgA multiple myeloma, fluoxetine administration, and rarely neoplasm. Hypocomplementemia is common and when it does occur, the association with SLE is highly likely. In one case, the lesions of urticarial vasculitis were induced by cold exposure and an IgG was found on serum protein electrophoresis (SPEP).
Autoantibodies to vascular endothelial cells were found in 82% of patients with urticarial vasculitis and SLE, 70% of patients with hypocomplementemic urticarial vasculitis, and in 14% of patients with urticarial vasculitis alone. They were found in only 32% of patients with SLE without urticarial vasculitis.
Urticarial vasculitis patients can be divided into those with normal complement levels (normocomplementemic) and those with depressed complement levels (hypocomplementemic). Normocomplementemic urticarial vasculitis tends to have a more benign course, whereas hypocomplementemic urticarial vasculitis is often associated with systemic disease and a more complicated disease course.
Urticarial lesions lasting more than 24 hours at any given location are characteristic. Pain and burning are more common than with typical urticaria. Diascopy may blanch much of the erythema, but hyperpigmentation and/or purpura remain. When the urticarial changes resolve, often purpura or other color change persists for a time. Angioedema may be associated.
Systemic findings have included anemia, arthralgias, abdominal pain, glomerulonephritis, ocular inflammation, and pulmonary disease. Laboratory abnormalities may include elevated erythrocyte sedimentation rate (ESR), decreased complement levels, decreased or absent C1q, and C1q autoantibody. In one study, the C1q autoantibody was found in 100% of patients with hypocomplementemic urticarial vasculitis syndrome (HUVS), 35% of patients with SLE, and almost no controls.
Workup may include drug history (e.g. dexfenfluramine), skin biopsy, CBC, ANA, Ro, La, rheumatoid factor, ESR, urine analysis, CH50, C3,C4, liver enzymes, hepatitis C serology, cryoglobulins, and serum protein electrophoresis (SPEP).
If a specific cause is found, it should be treated directly. Otherwise, prednisone may be used (e.g. 40-60 mg/day initially, then tapered). Azathioprine has been used (e.g. 50-100 mg/day). Other steroid-sparing agents include dapsone and hydroxychloroquine.
Agents to try if these fail include indomethacin and colchicine. Urticarial vasculitis caused by hepatitis C has responded to interferon-therapy.
Note the purpura left when the urticarial lesion fades.
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