How is Urticarial Vasculitis differentiated from typical urticaria?
• UV lesions typically last for more than 24 to 48 hours and often resolve with residual hyperpigmentation. True urticaria lesions (hives) last for <24 hours (usually 8–12 hours) and leave no trace.
• UV lesions are often characterized by pain and burning rather than pruritus, the sensory hallmark of true urticaria.
• UV lesions are typically 0.5 to 5 cm in diameter, whereas true urticaria may coalesce into large lesions of >10 cm.
• Symptoms or signs of systemic disease, such as fever, arthralgias, abdominal pain, lymphadenopathy, or abnormal urine sediment, tend to occur in HUVS and rarely in true allergic urticaria.
• The histology is LCV in UV, in contrast to edema of the upper dermis in true urticaria.
• Note that UV tends to involve the trunk and proximal extremities more than the distal lower extremities, which is unique compared with other causes of LCV.
