Urticaria vasculitis in a child: a case report and literature review.

Annular urticarial lesions in a child must establish a main differential diagnosis with urticaria multiforme, common urticaria, acute hemorrhagic edema of infancy, erythema marginatum, erythema annulare centrifugum, annular erythema in childhood, erythema multiforme, Sweet's syndrome, Schönlein-Henoch purpura, erythematosus lupus, several systemic vasculitis, and serum sickness.