Erythema multiforme

• Overview:

  • Immune-mediated, typically self limiting, mucocutaneous condition characterised by target lesions
  • Mucosal involvement = erythema multiforme major
  • Most cases precipitated by HSV
• Demographics:

  • Most common in young adults 20-40
  • Predominance in males
  • Genetic predisposition - HLA alleles
• Causes:

  • 90% of cases infection - HSV-1 most common
  • Medications - antibiotics, anti-epileptics, NSAIDs, vaccinations
  • Systemic disease - IBD, hepatitis C, leukaemia, lymphoma, solid organ malignancy
  • In many cases the underlying cause is not found
• Treatment is often not needed as episodes are typically self-limiting with no ongoing complications. However, ocular involvement should always prompt ophthalmology referral given the risk for more serious sequelae.
• Treatment of mild symptomatic cases:

  • Itch - oral antihistamines and/or topical steroids
  • Pain - for mild mucosal involvement, oral washes containing antiseptic or local anaesthetic
• Other treatments are dependent on cause:

  • Precipitating infections — treat appropriately (note treatment of HSV does not significantly alter the course of single episode erythema multiforme)
  • Offending medications — cease and avoid in future.
• Treatment of severe mucosal disease:

  • May require hospital admission for support of oral intake
  • Consider use of prednisone
• Treatment of recurrent disease:

  • At least 6 months of oral antiviral therapy (acyclovir/aciclovir) - even if a clear cause has not been identified
  • Remission can be difficult to achieve, may require trial of more prolonged therapy or alternative antiviral