Erythema Multiforme (EM) Flashcards
Main patient population that gets Erythema multiforme and in what seasons?
- young adults (M=F) in spring and fall
____ % of EM cases are caused by infection.
- 90%
What is the most common trigger of erythema multiforme?
- HSV (HSV1>HSV2)
Which HSV more commonly causes EM?
- HSV 1 > 2
Most common cause of EM minor>
- Herpes virus
Herpes labials outbreak usually precedes EM by how long?
- 1-3 weeks
Most common cause of EM major?
- Mycoplasma pneumoniae!! - will see severe mucous membrane involvement, atypical papular target lesions
EM caused by Mycoplasma pneumoniae will present with:
- severe mucous membrane involvement, atypical papular target lesions
EM can be caused by histoplasmosis capsulate, and can have concomitant _____
- erythema nodosum
____% of EM is drug induced.
- 10%
Drugs that can cause erythema multiforme?
- NSAIDS, antibiotics, sulfonamides, anti epileptics, TNF-alpha inhibitors
EM clinical presentation
- Abrupt- onset of erythematous macules–>papules and targetoid lesions affecting the extremities and face
Classic targetoid lesions of EM
- have three zones:
1) dusky center that may have vesiculation or necrosis
2) pale ring surrounding dusky center
3) Outer macular erythematous ring
Erythema multiforme lesions favor which body parts?
Face and distal extremities
Targetoid lesions that are papular or elevated are considered ____, whereas those that are nonpalpable or macular are considered ______
- elevated and papular= typical
- macular/nonpalpable= atypical
Note: Macular atypical targets are seen in SJS/TEN, but not EM
What type of targetoid lesios do you see in EM, typical or atypical?
typical!
- atypical (macular) are seen in SJS/TEN.
Presence of _____ target lesions and ____ distribution allow for reliable distinction of EM from SJS/TEN
- Elevated/papular target lesions and acrofacial distribution are EM, not SJS/TEN
Can either EM minor or major progress to SJS/TEN?
nope
Difference between EM minor and major?
EM Minor:
- NO systemic symptoms (e.g. Fever, arthralgias)
- Minimal mucosal involvement
EM Major:
- Systemic symptoms
- More severe mucosal involvement (e.g. Erosions of
buccal mucosa and lips)
Three main differences between EM and SJS?
1) EM = papular targetoid lesions vs SJS = +/- macular targetoid lesions
2) EM favors hands, extremities, and face vs SJS/TEN which relatively spares distal extremities
3) EM has specific associations (like HSV or mycoplasma pneumonia infections)
EM+history of subacute or discoid lupus=
Histology of Erythema multiforme will show:
In order of picture:
- Dead reds (dead keratinocytes)
- spongiosis
- Epidermal lymphocytes
- Superficial infiltrate w/ lymphocytes & histocytes
_____ % of EM lesions will have detectable HSV DNA by PCR in the target lesions?
- 80%
Treatment of EM?
- Symptomatic Tx as it is self limiting after two weeks
- for pruritis= antihistamines/TCS
- painful oral lesions= magic mouthwash
- if 2/2 recurrent HSV: HSV PPx with acylcovir 400mg daily or valacyclovir 500mg daily
Note: in severe cases can consider systemic steroids or immunosuppressants
