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Erythema Multiforme (Herpes Associated Erythema Multiforme)
- Acute hypersensitivity reaction to infections or drugs.
Predisposing factors
- Infection
- Herpes is the most common predisposing factor
- Mycoplasma
- Medications (least likely in EM minor)
- Allopurinol
- Sulfonamides
- Barbiturates
Clinical Presentation
- Target Lesion – pink red ring around a pale center
- Macular or papular rash with vesicles and bullae possible
- May affect mouth and eyes (difficulty swallowing)
- Itching
- Joint pain
- General malaise
- Fever
Labs, Studies and Physical Exam Findings
- Target Lesion – pink red ring around a pale center of
- Macular or papular rash with vesicles and bullae possible
- Purpuric macules (purple lesions due to hemorrhages in the skin)
- May affect mouth and eyes
- Biopsy is diagnostic, but clinical appearance is sufficient.
Treatment
- EM is self limiting and typically lasts 2-6 weeks. Typically no treatment is necessary
- Antihistamines along with topical steroids may be used to mitigate symptoms
Stevens Johnson Syndrome and Toxic Epidermal Necrolysis (TEN)
- Severe hypersensitivity reactions typically occurring 1-3 weeks after introduction of the offending agent.
- What’s the difference?
- Stevens Johnson syndrome (SJS) has less than 10% skin loss
- Toxic epidermal necrolysis (TEN) has greater than 30% skin loss
- SJS/TEN overlap has between 10% and 30% skin loss
Predisposing Factors
- Medications are the most common predisposing factor
- Penicillin
- Sulfonamides
- Quinolones
- Phenobarbital
- Tetracycline
- Phenytoin
- Allopurinol
- Cephalosporins
- NSAIDS
- Anticonvulsants
- Infection
- Graft vs. host disease
Clinical Presentation
- Fever can be very high
- Sore throat with difficulty swallowing
- Lesions in mouth
- Macular or papular rash with vesicles and bullae
- Purpuric macules (purple lesions due to hemorrhages in the skin)
- Lesions merge into large bull and slough off.
Labs, Studies and Physical Exam Findings
- Nikolsky sign
- Rubbing the skin leads to removal of the top layer of skin
- Loss of skin in sheets
- Necrotic epidermis
- At least two or more mucosal surfaces involved
- Biopsy is diagnostic
Treatment
- Discontinue causative substance
- Patient should be treated in a burn unit
- Fluid and electrolyte management is extremely important
- Steroid use is controversial
- Antibiotic use for secondary infection
