Erythema multiforme (EM), Stevens-Johnson syndrome (SJS),and toxic epidermal necrolysis (TEN) are acute hypersensitivity reactions characterized by cutaneous and mucosal necrosis.These syndromes represent a hypersensitivity reaction to a precipitating cause, usually infectious organisms or drugs. Thesedisorders were historically thought to represent a spectrum of the same disease process, and inconsistent use of these diseasenames led to further confusion. A consensus definition was published in 1993, and current literature favors that EM is distinct from the SJS/TEN spectrum of disease. The differential diagnosis of vesiculobullous eruptions is listed in Table 195-1.
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EM is a common, self-limiting, acute hypersensitivity syndrome characterized by the abrupt onset of round, deep red, well-demarcated macules and papules with a dusky gray or bullous center. The size may range from a few millimeters to a few centimeters, but most lesions are approximately 1 cm in diameter. The classic target lesion consists of three concentric rings; the outermost is red, the intermediate is white, and the center is a dusky red or purple. These can progress to edematous plaques or bullae. If blistering occurs, it is circumscribed
Prodrome of fever, headache, malaise, sore throat, cough, vomiting, diarrhea Extensive epidermal necrosis with mucosal involvement Frequently related to drugs (e.g., sulfonamides, anticonvulsants) Nikolsky sign
Generalized, tender erythema Nikolsky sign Occasionally associated with underlying infection such as osteomyelitis, septic arthritis, pneumonia Desquamation and moist erosions observed, especially in intertriginous areas More common in children younger than 5 years of age
Herpes simplex Grouped vesicles on erythematous base May be recurrent at same site— lips, eyes, cheeks, hands Reactivated by fever, sunlight, trauma, stress
Varicella Crops of vesicles on erythematous base (“dewdrops on rose petal”) Highly contagious May see multiple stages of lesions simultaneously Associated with fever
Grouped vesicles on erythematous base limited to one or several adjacent dermatomes Thoracic dermatomes most commonly involved in children Usually unilateral Burning, pruritus
Prodrome of fever, anorexia, sore throat Oval blisters in acral distribution, usually few in number Shallow, oral erosions on erythematous base in oral mucosa Highly infectious Peak incidence in late summer and in fall
Erythema multiforme Target lesions on acral sites May have involvement of mucosal surfaces Associated with herpes simplex virus infection Urticaria pigmentosa Red-brown macules and papules; bullous lesions are rare Darier sign Lesions appear in infancy and spontaneously resolve in childhood
Miliaria crystallina Clean, 1to 2-mm superficial vesicles occurring in crops Rupture spontaneously Intertriginous areas, especially neck and axillae
Hereditary: epidermolysis bullosa, incontinentia pigmenti, epidermolytic hyperkeratosis
Autoimmune: linear IgA disease, bullous pemphigoid, dermatitis herpetiformis
Modified from Nopper AJ, Rabinowotz RG: Rashes and skin lesions. In Kliegman RM, editor: Practical Strategies in Pediatric Diagnosis and Therapy, Philadelphia, 1996, WB Saunders.
and involves less than 10% of the body surface area. Cutaneous lesions are symmetrical and commonly involve acral areas such as the hands, feet, elbows, and knees. Involvement of the ocular, oral, and genital mucosa can be seen in some cases.