TWO PEDIATRIC CASES OF URTICARIA MULTIFORME

Urticaria multiforme is a morphological subtype of acute urticaria, often mistaken for erythema multiforme, serum sickness, or cutaneous vasculitis. Synonyms include acute annular urticaria, acute urticarial hypersensitivity syndrome, echymotic urticaria, and urticaria hemorrhagica. Diagnostic criteria are typical annular and polycyclic urticaria, echymotic changes, pruritus, acral edema, and absence of target lesions, necrosis, or bullous changes. Echymotic changes last 24-48 hours, with rapid response to antihistamines and corticosteroids. It typically affects children aged 4 months to 4 years. We describe two pediatric cases with typical clinical and laboratory features of urticaria multiforme. A 3-year-old boy was admitted with migratory, erythematous, pruritic wheals that appeared on the fourth day of fever, following antipyretic treatment. No prior medical history or recent vaccinations. By day 2, peripheral edema and diffuse erythema developed. Between days 3-5, polycyclic, ecchymotic wheals appeared along with new itchy lesions. An otherwise healthy 11-month-old girl was hospitalized with erythematous, pruritic wheals and annular, urticaroid, erythema multiforme-like lesions. Symptoms began on day 2 after a 7-day course of antibiotics for an upper respiratory infection. No prior medical history, allergies, or recent vaccinations. After corticosteroid and antihistamine treatment, the lesions resolved completely by over the course of one week in both cases.