Persistent swelling, red eruptions
A 20-month-old is seen because of skin swelling and diffuse red eruptions that causes her to refuse to walk. Urticaria multiforme is diagnosed. Supportive treatment with oral antihistamines is prescribed. The child is walking and playing 24 hours later.
Key Points
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• What's the diagnosis?• How would you treat her?
You are asked to evaluate a 20-month-old girl with skin swelling and a diffuse red eruption. She had a month-long history of coughing and sneezing, and developed subtle minimally itchy pink papules on her chest at the end of a 10-day course of oral cefdinir. Despite treatment with oral diphenhydramine and a single dose of oral prednisolone, the skin eruption progressed, and itching worsened. Today, she refused to walk because of swelling in her feet.
Urticaria multiforme (UM) was recently coined by Shah, et al to describe acute urticaria presenting with distinctive annular lesions.1 This clinical variant of urticaria and angioedema can easily be confused with erythema multiforme (EM).1-5 Some characteristics of UM include:
Expanding red papules and plaques develop central clearing, and many infants demonstrate lesions with dusky centers.4 Characteristic of urticaria, individual lesions are intensely pruritic, transient, and may disappear and reappear in different locations over minutes to hours.
Angioedema may involve the patient's face, trunk, and extremities. Dermatographism typically develops after scratching or rubbing against tight-fitting clothing.
Pathogenesis
Urticaria multiforme, like classic urticaria, is caused by a type I hypersensitivity reaction in which IgE triggers mast cell degranulation.
Drug reactions and infections are most commonly associated with urticaria.4 Although penicillin and sulfonamides are most commonly implicated in drug-induced skin eruptions, most skin eruptions are morbilliform. Cephalosporins are actually more commonly identified as the culprit in urticaria and angioedema.3
Differential diagnosis
Urticaria multiforme is most commonly confused with erythema multiforme or a serum-sickness like drug reaction (SSLDR).
Classic erythema multiforme is characterized by target lesions with a central dusky zone of necrosis surrounded by a ring of pallor and/or a ring of erythema. In erythema multiforme the lesions are usually fixed for five to seven days.1,2,5 There is a predilection for involvement of the distal extremities, particularly the palms and soles. Lesions with ulceration may develop on mucous membranes. Angioedema is rare, and dermatographism does not occur.
Urticarial papules and plaques also develop in SSLDR, and swelling may be prominent. However, as in erythema multiforme, the lesions are fixed for a week or longer, and pruritus is not prominent. Moreover, patients are usually systemically ill with fever, myalgias, arthralgias, and lymphadenopathy.
The differential diagnosis also includes morbilliform drug reactions, viral exanthems, Kawasaki syndrome, Henoch-SchF6nlein purpura, and acute hemorrhagic edema of infancy.
Treatment and prognosis
Treatment in UM is mainly supportive. Both H1 and H2 antihistamines may suppress symptoms. Systemic corticosteroids are not generally required, and should only be considered in the most severe patients, particularly when the airway is compromised. Individual lesions disappear within 24 hours, and the eruption usually runs a course over a week or less.
Our patient
The itching and swelling improved with administration of oral antihistamines. The next day she was walking and playing. The eruption cleared completely within a week.
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:e1177
2. Segal AR, Doherty KM, Leggott J, et al: Cutaneous reactions to drugs in children. Pediatrics 2007;120:e1082
3. Ibia EO, Schwartz RH, Wiedermann BL: Antibiotic rashes in children. Arch Dermatol 2000;136:849
4. Sackesen C, Sekerel BE, Orhan R, et al: The etiology of different forms of urticaria in childhood. Pediatr Dermatol 2004;21:102
5. Weston WL: What is erythema multiforme? Pediatr Ann 1996;25:106
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