Urticaria Multiforme

Authors:
Nicole Tillman, DO, and David Cleaver, DO
Northeast Regional Medical Center, Kirksville, Missouri

Citation:
Tillman N, Cleaver D. Urticaria multiforme. Consultant. 2017;57(11):672,674.

A 2-year-old girl presented with a pruritic rash. Her mother said the rash had begun after the girl had helped her father in a wheat field. The rash initially had appeared on her abdomen and back and then had spread to involve her face and extremities. The girl’s mother said the lesions appeared to come and go. The mother denied any fever or chills in her daughter and said that the girl had been eating and acting normally despite the rash. No medications had been recently started.

Physical examination. Erythematous, blanchable, arcuate, and targetoid wheals with dusky or light pink centers were present on the girl’s face, trunk, buttocks, and extremities. Mild edema was seen on her hands. No mucosal or conjunctival lesions were appreciated.

Diagnosis and treatment. Based on the history and clinical examination findings, a diagnosis of urticaria multiforme (UM) was made. The patient was treated with oral cetirizine, twice daily. Improvement was noted within 48 hours, and after 2 weeks, the lesions had completely resolved without scarring.

Discussion. Urticaria affects 15% to 20% of children at least once by adolescence.¹ Many variants exist, including UM, which is also known as acute annular urticaria. This urticarial subtype was first described in 1997 and is an allergic hypersensitivity reaction characterized by acute, blanchable, polycyclic wheals with dusky centers.^1,2 It may be mistaken for other dermatoses such as erythema multiforme (EM), urticarial vasculitis, and serum sickness–like reaction.^1-4

UM occurs primarily in children younger than 3 years.^1,2 Children present with pruritic, annular, polycyclic, violaceous wheals with ecchymotic centers or central clearing.^1-4 Individual lesions are transient, lasting less than 24 hours.⁴ The children appear well but may have a low-grade fever.⁴ Acral or facial edema is an associated finding in 60% to 100% of UM cases. Dermatographism occurs in roughly half of cases.^2-4 Triggers of UM include systemic antibiotics, antipyretics, and infections.^1,3

The diagnosis is made clinically and should not require a biopsy. If a biopsy is performed, the results will demonstrate dermal edema with a perivascular infiltrate and few scattered eosinophils, characteristic of urticaria.^1,3 UM is self-limiting but responds quickly to oral antihistamines. Lesions resolve in 8 to 10 days and heal without scarring.^1,3,4

To avoid unnecessary biopsies and tests, it is important to differentiate UM from clinical mimics.^2-4 The targetoid lesions of UM may be confused with the classic targetoid lesions of EM. In EM, skin necrosis, vesicles and/or bullae, and mucosal involvement occur. The targetoid lesions may occur on the palms and soles. Arthritis also may be associated, but acral and/or facial edema is not typically seen.^1,3 The individual lesions of EM are fixed and are associated with pain and burning, in contrast to the transient, pruritic lesions of UM.^2,4 EM is commonly associated with herpes simplex virus infection.

Urticarial vasculitis presents as wheals with a dusky center that look like the lesions of UM. The lesions are fixed and painful and heal with hyperpigmentation.^1,2 Urticarial vasculitis may be associated with facial and/or acral edema; however, unlike with UM, arthralgias are associated with the condition. Urticarial vasculitis most often affects adults, whereas UM most often affects young children. Infections, medications, and autoimmune diseases are associated with urticarial vasculitis.³

Serum sickness­–like reaction presents with urticaria or polycyclic wheals that can appear similar to the lesions in UM. The lesions of serum sickness–like reaction are fixed, in contrast to the transient lesions of UM. Lesions may develop on the feet, hands, and face. Patients present with a high fever, in contrast to patients with UM. Other associated symptoms of serum sickness–like reaction that are not seen in UM include myalgias, lymphadenopathy, and arthralgias. The eruption can last days to weeks. Cefaclor is a classic medication known to cause serum sickness–like reaction.^3,4

References:

1. Tamayo-Sanchez L, Ruiz-Maldonado R, Laterza A. Acute annular urticaria in infants and children. Pediatr Dermatol. 1997;14(3):231-234.
2. Shah KN, Honig PJ, Yan AC. “Urticaria multiforme”: a case series and review of acute annular urticarial hypersensitivity syndromes in children. Pediatrics. 2007;119(5):e1177-e1183.
3. Starnes L, Patel T, Skinner RB. Urticaria multiforme—a case report. Pediatr Dermatol. 2011;28(4):436-438.
4. Emer JJ, Bernardo SG, Kovalerchik O, Ahmad M. Urticaria multiforme. J Clin Aesthet Dermatol.  2013;6(31):34-39.