Erythema multiforme

Alternative names:

Lyell's syndrome; Stevens-Johnson syndrome; toxic epidermal necrolysis

Definition:

A skin disorder resulting from an allergic reaction.

Causes, incidence, and risk factors:

Erythema multiforme is a type of hypersensitivity (allergic) reaction that occurs in response to medications, infections, or illness. Medications associated with erythema multiforme include sulfonamides, penicillins, barbiturates, and phenytoin. Associated infections include herpes simplex and mycoplasma infections.

The exact cause is unknown. The disorder is believed to involve damage to the blood vessels of the skin with subsequent damage to skin tissues. Approximately 90% of erythema multiforme cases are associated with herpes simplex or Mycoplasma infections. The disorder occurs primarily in children and young adults.

Erythema multiforme may present with a classic skin lesion with or without systemic (whole body) symptoms. In Stevens-Johnson syndrome, the systemic symptoms are severe and the lesions are extensive, involving multiple body areas (especially the mucous membranes). Toxic epidermal necrolysis (TEN syndrome, or Lyell's syndrome) involves multiple large blisters (bullae) that coalesce, followed by sloughing of all or most of the skin and mucous membranes.