Erythema Multiforme

• vasculitic process leading to characteristic target lesions

• Hypersensitivity rash
• Severe form is erythema multiforme major or Steven-Johnson syndrome

Typical Patient

Symptoms / Signs

• Acute onset

• sudden appearance of lesions enlarging over few days then fading

  • may leave pigmentary changes

  • process settles in about 3 weeks

• Cutaneous
• Lesions

  • 'target' lesions

    • round or oval area of erythema

    • dusky, purplish centre

      • may become paler and blister

  • erythematous
  • polycyclic
  • annular
  • "target lesions"
  • may blister
• sites
  • symmetrical
  • limbs - hands and feet (palms and soles may be invovled)

  • distribution characteristically extensor surfaces, palms and soles

• if severe bullae may form

Variants

• Stevens-Johnson Syndrome

• Toxic Epidermal Necrolysis

Pathology

• vasculitis

• cell mediated response

• if severe may be necrosis of epidermis

• triggers

  • Herpes simplex

  • Mycoplasma pneumoniae

  • other viruses

    • orf

    • hepatitis

    • mumps

    • HIV

  • radiotherapy

  • cancers

  • lymphoma

  • connective tissue disorders

    • Wegeners granulomatosis

  • wide variety of drugs

    • sulphonamides

    • Penicillins

    • barbiturates

Investigations

Treatments

• not usually required

• acyclocvir (as 80% viral)
• ? oral steroids
• ? azathioprine

Prognosis

• usually settles in 3 weeks

• recurring if associated with herpes simplex otherwise repeated episodes rare

Complications

• Treatment

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