Updated: 7/9/2020

Erythema Multiforme

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  • A 33-year-old male presents to his physician complaining of several red lesions on his palms, back of hands, and on his lips. His past medical history is significant for recurrent herpes. 
  • Hypersensitivity reaction of the skin
  • Common, acute mucocutaneous disease with classic target-shaped lesions with symmetric distribution
  • Divided into erythema multiforme (EM) major and minor
    • major: involves mucous membranes and systemic signs
    • minor: no mucous membrane involvement and no systemic signs
  • Causes
    • most common = infection
      • Herpes simplex virus (most common cause) 
      • Mycoplasma pneumonia
      • upper respiratory infections
    • less common = drugs
      • e.g., sulfonamides, β-lactams, phenytoin
    • idiopathic
  • Often affects young adults (18 - 30 years old especially)
  • Distinct from SJS/TEN, which is a more severe mucocutaneous reaction that is usually caused by a medication
  • Skin
    • raised (papular), target lesions with multiple rings and dusky center (as opposed to annular lesions in urticaria)
      • three concentric zones of color from center to outer ring
        • central dusky/dark area that can be crust or vesicle
        • paler pink or edematous zone
        • peripheral red/dark ring
    • fixed lesions (as opposed to urticaria, in which lesions typically resolve within 24 hours)
    • negative Nikolsky sign (as opposed to SJS/TEN)
    • generally mild burning or itchiness; nontender
    • most commonly involves
      • palms/soles
      • backs of hands and feet
      • extensor aspects of forearms and legs
  • Must also examine mucosal surfaces and eyes
    • oral
    • genital/anal
    • iris
  • May have systemic signs (e.g., fever, prodrome)
  • Diagnosis is based on symptoms and clinical history
    • recent history of infection (e.g., herpes or mycoplasma) can aid diagnosis
  • SJS/TEN (flat lesions, tender, always with mucous involvement, + Nikolsky sign)
  • Urticaria (annular lesions)
  • Erythema nodosum
  • Viral exanthems
  • EM major
    • corticosteroids
    • opthalmology consult if ocular involvement
  • EM minor – usually self-limited
    • supportive care
  • Treat underlying cause if identified
    • oral acyclovir for HSV
Prognosis, Prevention, and Complications
  • Prognosis
    • typically self-limited
  • Prevention
    • treat chronic herpes infections
    • if recurrent herpes associated-EM
      • oral acyclovir, valcyclovir, or famciclovir as continuous suppressive therapy
  • Complications
    • usually none associated with EM minor
    • potential ocular complications with EM major
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