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Stevens-Johnson Syndrome and Erythema Multiforme

Erythema multiforme (EM) is an acute hypersensitivity reaction characterized by distinctive skin lesions and mucous membrane involvement that has a spectrum of severity. It occurs in two forms: the more common "minor" type and the more severe "major" type, also called Stevens-Johnson syndrome (SJS). Sometimes erythema multiforme includes toxic epidermal necrolysis (TEN) or Lyell disease. Erythema multiforme minor first was described completely by von Hebra in 1866; Stevens and Johnson described the major variant in 1922. Erythema multiforme occurs more often in males, and 20% to 50% of cases occur in the pediatric age group, although rarely in those younger than age 3 years. A winter predominance is suggested Stevens-Johnson Syndrome.

The pathologic process responsible for erythema multiforme is unknown. A review of the literature generates an extensive list of causative or inciting agents. Most frequently mentioned are sulfonamide antibiotics and anticonvulsants, both used commonly in pediatric practice.

Currently, the evidence suggests that erythema multiforme is caused by an immune reaction. Histologically the lesions are similar to those seen with graft-versus-host disease reactions. Immune complexes have been demonstrated in the serum and lesions, but their role in the pathology.

EM minor is characterized by a distinctive rash. Classically, the rash is an erythematous ring that has a dusky center--the target or iris lesion. The rash also may be macular, papular, and/or vesicular. Usually one type of lesion predominates. The lesions have a typical distribution: most commonly, the extensor surfaces of the extremities symmetrically, but sometimes the trunk and face are included. In addition, involvement of a single mucous membrane is possible. Oral lesions may be bullous or ulcer-like.

In contrast, Stevens-Johnson syndrome typically is preceded by a serious prodrome consisting of fever, myalgias, arthralgias, sore throat, and abdominal complaints. This is followed by rapid (hours to days) and widespread bullous eruption involving the extremities, trunk, and at least two mucous membranes. The total body surface area involved can be extensive, possibly leading to fluid and electrolyte disturbances and secondary infection. Lesions of the mouth are more impressive than in EM minor.

The rash of TEN starts as a generalized sunburn-like erythema, which quickly progresses to full-thickness epidermal sloughing, sometimes secondary to trivial trauma (Nikolsky sign).

EM is a clinical diagnosis. The classic symmetrically distributed, target-lesion rash usually confirms the diagnosis. In contrast to urticaria, EM is rarely pruritic and the duration of the rash is longer.

The treatment for EM minor

Any inciting agents should be discontinued or treated, if possible. Cohen suggests that cases secondary to HSV be treated with a 5-day course.

Weston et al strongly discourage the use of steroids in EM minor because of the association with HSV. Children who have Stevens-Johnson syndrome and TEN need to be hospitalized, and the severity of skin involvement may necessitate transfer.

Careful attention to fluid and electrolyte levels, optimal nutritional support, and meticulous skin care are mandatory. Detection and treatment of infection can be lifesaving. Ophthalmologic attention should be on a daily basis. The use of steroids in Stevens-Johnson syndrome still is debated. Prendiville, et al state, "Stevens-Johnson syndrome is not a steroid-responsive dermatosis." Cohen reports on some studies that discourage steroid use and others that suggest a short course.