Erythema multiforme

Background

• Erythema Multiforme (EM) is an acute, self-limited skin condition
• Peak incidence in second and third decades of life
• Despite multiple associations, thought to be triggered by HSV in most cases
• Usually self-limited and resolves within 2-6 weeks; may recur
• Wide spectrum of severity
  • Classified as Erythema multiforme minor or Erythema multiforme major

Precipitants

• Infections:
  • Viral: HSV, hepatitis, influenza A
    • HSV responsible for ~70% of cases, making it the most common etiology
  • Fungal: dermatophytosis, histoplasmosis, coccidioidomycosis
  • Bacterial: streptococcus, mycoplasma, tuberculosis
• Drugs:
  • Antibiotics (penicillin, sulfonamides), anticonvulsants (phenytoin, barbiturates), NSAIDS, aspirin, antituberculous meds, allopurinol, etc.
• Collagen Vascular Disorders:
  • RA, SLE, dermatomyositis, polyarteritis nodosa
• Others:
  • Pregnancy, cold weather, sunlight, contact exposure, foods, malignancy, hormonal

Clinical Features

Erythema Multiforme

Erythema multiforme minor of the hand (note of make of the blanching centers of the lesion)

• Erythematous or violaceous macules, papules, vesicles, or bullae
• Target lesions with “three zones of color” are the hallmark of EM
• Distribution is usually symmetric, most commonly involving palms/soles, the backs of the hands/feet, and/or the extensor surfaces of the extremities
• Not to be confused with SJS/TEN, which are now considered separate from the EM spectrum

Erythema multiforme minor

• Typical targets or raised, edematous papules distributed peripherally
• No mucous membrane involvement

Erythema multiforme major

• Same as EM minor + involvement of 1+ mucous membranes
• Epidermal detachment involves < 10% of total body surface area
• Some cases can be severe or even fatal

Differential Diagnosis

• Fixed drug reaction
• Stevens Johnson Syndrome and Toxic Epidermal Necrolysis
• Subacute cutaneous lupus erythematosus
• Urticaria
• Viral exanthems
• Allergic or irritant contact dermatitis

Vesiculobullous rashes

Febrile

• Diffuse distribution
  • Varicella
  • Smallpox
  • Disseminated gonococcal disease
  • DIC
  • Purpural fulminans
• Localized distribution
  • Necrotizing fasciitis
  • Hand-foot-and-mouth disease

Afebrile

• Diffuse distribution
  • Bullous pemphigoid
  • Drug-Induced bullous disorders
  • Pemphigus vulgaris
  • Phytophotodermatitis
  • Erythema multiforme major
• Localized distribution
  • Contact dermatitis
  • Herpes zoster
  • Dyshidrotic eczema
  • Burn
  • Dermatitis herpetiformis
  • Erythema multiforme minor
  • Poison Oak, Ivy, Sumac dermatitis
  • Bullosis diabeticorum

Evaluation

• Usually made clinically
• In severe cases, work-up includes basic labs and cultures
• Punch biopsy: to confirm the diagnosis and to rule out other diagnoses (looks different from SJS/TEN histologically)

Management

• Search for underlying cause
  • Prompt withdrawal of suspected drug/agent causing symptoms
• Symptomatic treatment
  • Oral antihistamines, analgesics, local skin care
  • If oral involvement: soothing mouth washes
  • If eye involvement: topical lubricants, cleaning of conjunctiva, and removal of fresh adhesions
  • Mild cases with localized lesions, may consider topical corticosteroids. Use of systemic steroids is controversial
• Consultation (rarely) with the following may be necessary: dermatologist, ophthalmologist, burn surgeon

Disposition

• For mild cases, treat as above with dermatology follow-up
• For severe cases with multiple lesions / severe mucous membrane or tracheobronchial involvement with impaired PO intake, dehydration, or secondary infection: inpatient admission
  • May require specialized ICU or burn unit care

See Also

• Generalized rashes

References

• Plaza J, Prieto V. Erythema Multiforme. Medscape fromWebMD. Sept 2014
• Rosen’s Emergency Medicine
• http://www.ncbi.nlm.nih.gov/pubmed/25059772
• http://www.ncbi.nlm.nih.gov/pubmed/18723713
• Image source: Weinberg A, Prose N, Kristal L. Color Atlas of Pediatric Dermatology. McGraw-Hill Companies, Inc. Copyright 2008, 1998, 1990, 1975

Authors

Ross Donaldson