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All That Forms Rings Is Not Erythema Multiforme

Acute annular urticaria is common in childhood, benign, and self-limiting, but the lesions can be misleading.

Acute annular urticaria (ring-shaped hives) is a benign cutaneous hypersensitivity reaction that occurs frequently in childhood. The condition is sometimes mistaken for other ring-shaped disorders — most often, erythema multiforme and less commonly, serum-sickness–like reactions.

To better distinguish the clinical features of this condition from the features of erythema multiforme and serum-sickness–like reaction, and to increase awareness of this diagnosis, pediatric dermatologists at a large children’s hospital characterized the disease in a case series of 18 children.

Most of the patients (83%) were 2 months to 3 years of age. The most common referring diagnosis was "rash" or "erythema multiforme." A majority (67%) presented with antecedent upper respiratory infection, otitis media, or viral symptoms; fever was present in eight patients (44%). Recent antibiotic use was reported in 44%, and 11% had recently been immunized. The typical features of urticaria and angioedema were observed in most, and pruritus was nearly universal (94%), although visible excoriation was rare. Edema of the hands, feet, or both was seen in 61%. No patients had the true target lesions of erythema multiforme, and none had skin necrosis, blistering, mucous membrane involvement, arthralgias, or arthritis. Systemic antihistamines, sometimes in combination with ranitidine, were required for symptom relief in the majority of patients, and the clinical signs and symptoms remitted within 2 to 12 days.

Comment: Acute urticaria is extremely common in childhood: Most children will experience this transient hypersensitivity reaction at least once. Diagnostic confusion may arise when the urticaria is ring-shaped or polycyclic, and being able to distinguish this self-limited condition from other, more serious conditions is important. The descriptions in this report nicely illustrate that although annular urticaria is ring-shaped, it never forms the true target lesions of erythema multiforme. Furthermore, no matter the shape, urticaria always behaves in the same way — the wheals are evanescent rather than fixed, and they respond to oral antihistamines. The value of renaming acute annular urticaria "urticaria multiforme," as the authors propose, is debatable. Nevertheless, this paper should be required reading for all physicians and other health providers likely to encounter ring-shaped rashes in children.

— Mary Wu Chang, MD

Published in Journal Watch Dermatology November 2, 2007

Citation(s):

Shah KN et al. "Urticaria multiforme": A case series and review of acute annular urticarial hypersensitivity syndromes in children. Pediatrics 2007 May; 119:e1177.

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