Urticaria Multiforme

Five days after beginning treatment with oral amoxicillin for a positive rapid group A streptococcus test result, an 18-month-old girl presented with widespread, large, annular, itchy lesions (A-D), along with a fever and decreased oral intake.

She had no other lesions. Physical examination findings also included swelling of her face, hands, and feet. The remainder of the examination results were normal. Results of a complete blood count and laboratory tests, including C-reactive protein and Epstein-Barr virus, were normal.

The girl received a diagnosis of urticaria multiforme, a benign, cutaneous hypersensitivity reaction. Urticaria multiforme, a term that recently has been proposed as a replacement for acute annular urticaria,^1,2 is characterized by acute onset of large, pruritic, polycyclic, annular lesions with ecchymotic centers, resembling the “target lesions” of erythema multiforme, with which it is frequently confused. Peak incidence of urticaria multiforme is between the ages of 4 months and 4 years.

In as many as 70% of cases, urticaria multiforme is associated with angioedema of the face, hands, and legs, along with fever; these symptoms can cause it to be misdiagnosed as serum sickness or Kawasaki disease.

Patients with urticaria multiforme respond well to antihistamines. The condition has a self-limiting course of 8 to 10 days. It is almost universally associated with pruritus and fever, and dermatographism occurs in about half of cases.

Approximately 60% to 70% of patients with urticaria multiforme have had recent viral or bacterial illness, and about half have a recent or current history of antibiotic therapy. Some cases have been associated with immunizations.

Our patient’s amoxicillin was discontinued, and she was started on cetirizine, a few days after which her rash had improved significantly (E and F).

References:

1. 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.

2. Starnes L, Patel T, Skinner RB. Urticaria multiforme—a case report. Pediatr Dermatol. 2011;28(4):436-438.