Erythema Multiforme

4 Dec

Submitted by Amit Kumar. 


*Acute immune mediated, distinctive target-like lesions

*Erythema multiforme “major”: EM with mucosal involvement (ocular, oral, genital)

*Population: Mostly 20-40yo, M > F

*Precipitators: #1 = infection (HSV most common, mycoplasma in children).

Other causes: medications, malignancy, autoimmune disease, immunizations, radiation, sarcoidosis, and menstruation

*Commonly confused with Stevens Johnson Syndrome (<10% body surface area) and Toxic Epidermal Necrolysis (>30% BSA): Also targetoid lesions with mucosal involvement, but mostly drug-induced

*Evaluation & diagnosis:

  • Skin punch biopsy (to check for HSV antigens in potential subclinical case, differentiate from autoimmune bullous diseases such as pemphigus or pemphigoid)
  • sampling of perioral lesions (for HSV PCR/Tzanck smear),
  • serologic tests for M. pneumoniae,
  • check labs (CBC, ESR, LFTs),
  • wound culture (if concerned for secondary infection)


  • Acyclovir 400mg q4h (if HSV), Prednisone 60mg daily followed by ~two week taper.
  • Symptomatic treatment: Benadryl, ELTA cream
  • Consult ophthalmology for ocular involvement
  • Monitor nutrition (if compromised due to oral involvement)
  • Pain control
  • Prophylaxis: Acyclovir 400mg BID (for HSV)

References:; picture 1, picture 2


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