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A. Classification of Erythema Multiforme (EM)

  1. E. Multiforme Minor
  2. E. Multiforme Major [3]
    1. Stevens Johnson Syndrome (SJS)
    2. Toxic Epidermal Necrolysis (TEN)
  3. SJS
    1. Target lesions and other characteristics of EM minor
    2. Diagnosis requires mucous membrane involvement
  4. TEN may occur with no clear evidence of progression through EM Minor

B. Characteristics

  1. Rash begins as distinct lesions
  2. Target-like lesions which evolve over 1 week
  3. Dull red macule or wheal with central papule or vesicle
  4. Macule becomes papular and plaque-like
  5. Center forms classic concentric rings of color (often 3 rings)

C. Progression

  1. Prodrome: fever, headache, malaise, cough, prostration and sore throat may be present
  2. Target Lesions
    1. Initially, erythematous macules
    2. Progress to papules vesicles or bullae
    3. Surrounding areas may be blanched or hyperpigmented
    4. Central areas may become gray and blister
    5. Surrounding rings may be due to extravasated erythrocytes, superficial vasodilation
  3. May blister and then appear purpuric or even necrotic
  4. EM major may involve viscera
  5. Pathophysiology
    1. E. multiforme is a vasculitis with immune complex formation
    2. Minor reactions may be due to herpes simplex or mycoplasma
    3. Major reactions can be life-threatening (often drug induced)
    4. The relationship of EM to some cases of TEN is unclear [4]

D. Differential Diagnosis of Erythema Multiforme

  1. Urticaria
  2. Henoch-Schnlein Purpura
  3. Angioneurotic Edema
  4. Measles
  5. Morbilliform (measles-like) drug rash
  6. Differential Diagnosis of Bullous Erythema Multiforme
    1. Bullous lupus
    2. Bullous pemphigoid
    3. Bullous drug eruptions
  7. Staphylococcal scalded skin syndrome may be mistaken for TEN

E. Diseases Associated with Erythema Multiforme [3]

  1. Infections
    1. Herpes Simplex or Zoster
    2. Mycoplasma
  2. Drug Reaction
    1. Sulfas
    2. Anticonvulsants
    3. Other antibiotics (eg. penicillin)
    4. NSAIDs
    5. Some topical agents
  3. Weak Associations
    1. Collagen Vascular Disease
    2. Protozoan Infection
    3. Fungal Infection
    4. Vaccination
    5. Skin Allergies
    6. Underlying CA
    7. Lymphoma / Leukemia

F. Diagnosis

  1. Clinical Suspicion - appearance of rash is usually helpful
  2. Skin biopsy
  3. Mucous membrane involvement
    1. Culture for herpes simplex virus
    2. Chest radiograph for mycloplasma (± serological diagnosis)
    3. Antimicrobial therapy should be directed at these organisms if found

G. Treatment [2]

  1. Supportive Therapy is mainstay
    1. Intravenous fluids
    2. Topical agents for mucous membrane - especially with ocular involvement
    3. Frequent examination and cleaning of ulcerated lesions is recommended
    4. If ocular involvement occurs, ophthalmologist should be consulted immediately
  2. Discontinue or change current medications
  3. Histamine Blockers
    1. Of variable efficacy, mainly for patient comfort
    2. Diphenhydramine (Benadryl®) 25-50mg every 6-8 hours OR
    3. Hydroxazine (Atarax®) 25-50mg every 6-8 hours
  4. Glucocorticoids
    1. Efficacy is unclear, but may be beneficial (1mg/kg/d po) in adults
    2. Glucocorticoids mainly improve patient comfort in early, extensive erythema
    3. Concern is increased infection risk; use is not advised in cases with signs of TEN
  5. Antibacterials
    1. Topical agents may be used to prevent superinfection
    2. Routine prophylaxis is not recommended
    3. Anti-herpes agent (acyclovir) may be effective in herpes-virus associated disease
    4. Anti-herpes drugs will treat current infection and suppress virus

References

  1. Stampien TM and Schwartz RA. 1992. Am Fam Phys. 46(4):1171 abstract
  2. Fine JD. 1995. NEJM. 333(22):1475 abstract
  3. Thaler SJ and Bailey EM. 1996. NEJM. 334(19):1254 (Case Report)
  4. Becker DS. 1998. Lancet. 351(9113):1417 abstract