Urticaria multiforme--a case report.

The term "urticaria multiforme" has recently been proposed to replace acute annular urticaria and refers to a benign cutaneous hypersensitivity reaction characterized by the acute onset of large, polycyclic, and annular wheals with ecchymotic centers. It is associated with acral and facial angioedema, dermatographism, favorable response to antihistamines, and a self-limited course. It is most often mistaken for erythema multiforme and occasionally for serum sickness-like reaction. We report a case of urticaria multiforme in a 4-month-old infant, followed by a review of the literature.