Erythema Multiforme The 5 Minute Pediatric Consult


	Erythema Multiforme

Christen Mowad

Database
Differential Diagnosis
Data Gathering
Physical Examination
Laboratory Aids
Therapy
Follow-Up
Bibliography

DATABASE

DEFINITION

Erythema multiforme (EM) is an acute self-limited cutaneous eruption with many different multiform lesions. It is characterized classically as a target or iris lesion, but can appear as erythematous macules, papules, vesicles, and bullae with mucosal involvement. There are many triggers of EM, which is thought to encompass a spectrum of disease from relatively mild disease (EM minor) to severe forms with more than one mucosal surface involved (EM major or Stevens-Johnson syndrome). Some authors include toxic epidermal necrolysis (TEN) as the most severe form of EM, characterized by widespread erythema, bullae, and sloughing of large sheets of skin, with significant morbidity and mortality.

CAUSES

The major causes of EM, which is thought to be an immune-mediated reaction, include drugs such as sulfa, penicillin, and phenytoin, and infections such as herpes simplex virus and Mycoplasma.
There are a host of other etiologic factors, including exposure to various chemicals and tumors. The eruption usually occurs 1 to 2 weeks after the initial exposure.
Often, the causative factor is not identified.
Recurrent EM is generally secondary to herpes simplex virus.

GENETICS

Although simultaneous cases in family members have been reported, the disease is not genetic.

PATHOLOGY

The pathologic findings vary according to the lesion examined. Biopsy reveals necrosis of keratinocytes to varying degrees, depending on the clinical lesion biopsied. There is moderate-to-severe papillary dermal edema with mild-to-moderate perivascular dermal infiltrate composed predominantly of mononuclear cells and also some eosinophils (particularly if drug-related). Subepidermal blistering may be seen. Extravasated blood cells are found, but there is no evidence of vasculitis. Hydropic degeneration of the basement membrane also can be seen, as can epidermal spongiosis.

EPIDEMIOLOGY

Erythema multiforme is seen in approximately 1% of all dermatology patients and has an equal incidence in men and women. (Some studies suggest a slightly higher incidence of EM minor in women.)
The disease occurs predominantly in young adults and is believed by some to occur more frequently in spring and summer, with the more severe form of EM major occurring in the winter.

COMPLICATIONS

Erythema multiforme minor is generally self-limited, with rare complications.
In EM major, mucosal involvement can lead to stricture formation of the urethra, trachea, and esophagus, as well as conjunctivitis, corneal erosions, and, rarely, blindness.
Pneumonitis, nephritis, hepatitis, and infection are other reported complications.
In TEN, mortality and morbidity are high, with death occurring from sepsis.

DIFFERENTIAL DIAGNOSIS

Classic presentation with targetoid lesions and mucosal involvement is generally not a diagnostic challenge; however, given the many forms of presentation, the diagnosis of EM can be difficult. The differential diagnosis can be extensive, depending on the presentation, and includes:

Viral exanthem
Bullous impetigo
Staphylococcal scalded-skin syndrome
Bullous pemphigoid
Urticaria
Urticarial vasculitis
Systemic lupus erythematosus
Serum sickness
Pemphigus vulgaris
Secondary syphilis
Chicken pox
Rocky mountain spotted fever

DATA GATHERING

HISTORY

The cutaneous findings are sometimes preceded by a prodrome with fever and malaise. A careful drug and exposure history, as well as any signs or symptoms of infection or herpetic lesions, may reveal the etiologic cause. Inquire in detail about the patient’s drug history, over-the-counter preparations, and signs or symptoms of infection or herpetic lesions.

PHYSICAL EXAMINATION

Erythema multiforme classically appears as target lesions characterized by a dark, dusky center surrounded by a pale zone and then a zone of erythema. The lesions are typically acrally distributed.
The lesions occur in many forms and can appear as red macules, papules, urticarial lesions, or vesicles and bullae.
Mucosal involvement with superficial denudation can occur in the eyes, nasopharyngeal mucosal, or anogenital region.

LABORATORY AIDS

TESTS

There are no diagnostic laboratory tests; however, biopsy is often helpful, and other tests may help identify a cause.
A WBC count with differential, looking for eosinophilia, may help identify a drug as causative.
Cultures and chest x-ray study to evaluate for herpes or pneumonia
Cold agglutinins associated with Mycoplasma
Antistreptolysin-O titers and leukocytosis may identify a particular infectious cause.
ESR may be elevated, but is nonspecific.
A chest x-ray study may help identify an infectious cause of EM.

THERAPY

MILD FORMS

Mild forms of EM resolve spontaneously without scarring and require only supportive therapy, including antihistamine or topical steroid for pruritus associated with the lesions.
Oral lesions are often painful, and oral preparations to swish and spit, made of viscous lidocaine or diphenhydramine, may provide relief.
Treatment of the underlying process is helpful (e.g., acyclovir for herpes simplex virus-associated cases).

ERYTHEMA MULTIFORME MAJOR

May be life-threatening and can require hospitalization
Supportive care, ophthalmology consultation, monitoring of fluid and electrolyte balance, and vigilant watch for infection are necessary.
Antibiotics, analgesics, and local care including compresses with acetic acid soaks or saline will help decrease the incidence of infection.
The use of systemic steroids is controversial, but when helpful, they are given early in the course of disease for approximately 2 weeks when there is no contraindication, such as infection.

TOXIC EPIDERMAL NECROLYSIS

High associated mortality is often secondary to infection.
Care is ideally at a burn center, with careful attention to infection and to fluids and electrolytes.
Antibiotics, local compresses with acetic acid, or saline can help prevent superinfection.
The use of systemic steroids is controversial, and is most effective when started early. The benefits and risks, including infection, must be weighed.

FOLLOW-UP

Mild forms of EM are acute and self-limited, with lesions resolving in 2 to 4 weeks, with postinflammatory hyperpigmentation or hypopigmentation.
Sequelae due to mucosal scarring can occur.
Severe forms of EM major or TEN have associated morbidity and mortality.
When recurrent, EM is often associated with herpes simplex virus.

ICD-9-CM 695.1

BIBLIOGRAPHY

Bondi EE, Jegasothy BV, Lazarus GS. Dermatology diagnosis and therapy. Norwalk, CT: Appleton & Lange, 1991.

Duvic M. Erythema multiforme. Dermatol Clin 1983;1(2):493–496.

Huff JC, Weston WL, Tonnessen MG. Erythema multiforme: a critical review of characteristics, diagnostic criteria and causes. J Am Acad Dermatol 1983;8(6):763–775.

Lever WF, Schaumberg-Lever G. Histopathology of the skin, 7th ed. Philadelphia: Lippincott, 1990.

Weston WL, Badgett JT. Urticaria. Pediatr Rev 1998;19(7):240–244.

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