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LeenaKoulu

Erythema Multiforme

Essentials

  • Erythema multiforme (EM) is an independent syndrome usually triggered by a viral or bacterial infection, most commonly by Herpes simplex or mycoplasma. Especially in children, a COVID-19 infection can trigger EM. A drug can also act as a trigger (in less than 10% of the cases). However, the aetiology frequently remains unknown.
    • According to current knowledge, drug-induced Stevens-Johnson syndrome and toxic epidermal necrolysis (TEN) are two forms of a separate syndrome that includes EM-like mucosal changes but the skin symptoms are different.
  • Patients with Stevens-Johnson syndrome or TEN must be referred immediately to specialist care.

Symptoms

  • Erythema multiforme
    • EM minor: symmetrical lesions predominantly on the limbs and face with a characteristic cockade pattern (target lesions) of 1-2 cm in diameter, which may have a small central vesicle (pictures 1 2 3 4 5 6).
    • EM major: the rash is more severe, the vesicles are large and mucosal involvement is present (pictures 7 8 9 10 11).
    • Patients are usually young adults.
    • Lesions develop over a few days and do not change their location.
    • Mild disease forms heal spontaneously within 1-3 weeks.
    • Symptoms may recur.
    • EM will not progress into toxic epidermal necrolysis.
    • The patient usually has mild fever as a general symptom and feels generally ill.
    • Particularly mycoplasma and Chlamydia pneumoniae infections may cause, especially in children, a clinical picture where the primary symptom consists of breaks in the oral mucosa and there are only few or no findings on the skin.
  • Stevens-Johnson syndrome and toxic epidermal necrolysis (TEN)
    • Different degrees of the same drug reaction
    • Stevens-Johnson syndrome (picture12) is a drug reaction with purpuric lesions involving less than 10% of total body surface area. Eroding vesicles are present on the skin and mucous membranes.
    • Toxic epidermal necrolysis (Lyell's syndrome) (picture 13) is a serious drug reaction with epidermal detachment involving over 30% of total body surface area and mucosal erosions. The patient will have systemic symptoms and need aggressive treatment.
    • The most common triggering agents are non-steroidal anti-inflammatory drugs, antimicrobial drugs, antiepileptics and allopurinol.

Diagnosis

  • Diagnosis is based on the clinical picture.
  • Histopathological findings are non-specific.

Treatment

  • EM minor
    • Mild forms of EM resolve without treatment.
    • If the bacterial infection that triggered the reaction is known, it should be treated.
    • If the reaction was triggered by a drug, the drug is discontinued.
  • EM major
    • Systemic glucocorticoids for 3-4 weeks are generally prescribed, even though no clear evidence is available on their efficacy. The starting dose of prednisone or prednisolone is 30-60 mg/day.
    • A dermatologist should be consulted for appropriate topical treatment.
    • An ophthalmologist should be consulted if the patient has eye symptoms.
    • Frequently recurring episodes of EM caused by the Herpes simplex virus may be an indication for prophylactic medication against herpes.
  • Stevens-Johnson syndrome: immediate referral to hospital
  • Toxic epidermal necrolysis: the patient needs high dependency/intensive care.

    References

    • Sokumbi O, Wetter DA. Clinical features, diagnosis, and treatment of erythema multiforme: a review for the practicing dermatologist. Int J Dermatol 2012;51(8):889-902. [PubMed]
    • Mawhirt SL, Frankel D, Diaz AM. Cutaneous Manifestations in Adult Patients with COVID-19 and Dermatologic Conditions Related to the COVID-19 Pandemic in Health Care Workers. Curr Allergy Asthma Rep 2020;20(12):75. [PubMed]
    • Daneshgaran G, Dubin DP, Gould DJ. Cutaneous Manifestations of COVID-19: An Evidence-Based Review. Am J Clin Dermatol 2020;21(5):627-639.[PubMed]