Skin nontumor
Lichenoid and interface reaction patterns
Erythema multiforme


Topic Completed: 1 July 2011

Minor changes: 19 March 2020

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PubMed Search: Erythema multiforme [title] skin

Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hamodat M. Erythema multiforme. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumorerythemamultiforme.html. Accessed May 29th, 2020.
Definition / general
  • Acute, self limited, hypersensitivity reaction to infections (coccidioidomycosis, herpes simplex, histoplasmosis, leprosy, mycoplasma, typhoid), drugs (penicillin, phenylbutazone, phenytoin, salicylates, sulfa), carcinoma / lymphoma, or collagen vascular disorders
  • Affects skin (distal extremities, palms, soles) and mucous membranes with target lesions
  • Also sore throat and malaise
  • Any age
  • Commonly recurs but rarely persists
Clinical features
  • Variable (multiform) lesions, including papules, macules, vesicles, bullae, target lesions
  • Commonly in mucous membranes; also elbows, knees, extensor surface of extremities
Clinical images

Contributed by Mark R. Wick, M.D.


Images hosted on other servers:

Target lesions

Microscopic (histologic) description
  • Subepidermal bullae with basement membrane in bullae roof due to dermal edema
  • Severe dermal inflammatory infiltrate (includes lymphocytes, histiocytes)
  • Eosinophils may be present, but neutrophils are sparse or absent
  • Overlying epidermis often demonstrates liquefactive necrosis and degeneration, dyskeratotic keratinocytes
  • May also have dermoepidermal bullae with basal lamina at floor of bullae
  • Variable epidermal spongiosis and eosinophils
  • No leukocytoclasis, no microabscesses, no festooning of dermal papillae

  • Note: erythema multiforme may have variable histologic changes from toxic epidermal necrolysis to dermal disturbances
Microscopic (histologic) images

Contributed by Mark R. Wick, M.D.



Images hosted on other servers:

Various images

Positive stains
  • Granular C3 and IgM at basement membrane and in vessels
Differential diagnosis
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