Title: GZ / The Grenz Zone Season 2 / 21 Erythema Multiforme
Tags: GZ DermnetNZ

Q: [...] presents as an abrupt-onset of erythematous macules that turn into papules and targetoid lesions affecting the extremities & face usually in young adults
A: Erythema multiforme
Back Extra: Classic targetoid lesions have 3 zones:
1. Dusky center that may have vesiculation
2. Middle pale ring with 3. outer erythematous ring
Pearl: Targetoid lesions that are papular or elevated are considered typical targets, whereas those that are nonpalpable or macular are considered atypical targets

Q: Erythema multiforme [minor or major] presents with minimal mucosal involvement and NO systemic symptoms
A: minor
Back Extra: Both major and minor have typical papular target lesions on extremities and face, and neither progress to Steven-Johnson Syndrome or Toxic Epidermal Necrolysis

Q: Erythema multiforme [major or minor] presents with severe mucosal involvement (erosions of buccal mucosa and lips) and systemic symptoms (fever, arthralgias)
A: major
Back Extra: Both minor and major have typical papular target lesions on extremities and face, and neither progress to Steven-Johnson Syndrome or Toxic Epidermal Necrolysis

Q: What are the 3 main differences between Erythema Multiforme and SJS?
1. EM has [macule or papule] targetoid lesions vs. SJS which has [macule or papule] targetoid lesions
2. EM favors the hands, extremities, and face vs. SJS which relatively spares [...] extremities
3. EM has different specific associations
A: papular; macular; distal
Back Extra: EM associations: 90% of cases are associated with infections (HSV & Mycoplasma pneumoniae)
SJS > 90% associated with medications

Q: What syndrome presents with a history of acute, subacute or discoid lupus and Erythema multiforme-like lesions?
[...]
A: Rowell's Syndrome

Q: On histology, Erythema multiforme presents with spongiosis, vacuolar interface, scattered epidermal necrotic keratinocytes, and superficial infiltrate with [cell type] & histiocytes
A: lymphocytes

Q: Symptomatic treatment is used in Erythema multiforme due to the fact that it is self-limiting after [number] week(s)
A: 2
Back Extra: Pruritis: anti-histamines (diphenhydramine or loratadine) + mild topical steroid
Painful oral lesions: "Magic Mouthwash" (combo of Benadryl, viscous lidocaine, and Maalox with or without corticosteroids or nystatin)
If 2/2 recurrent HSV: HSV prophylaxis with Acyclovir 400mg daily or Valacyclovir 500mg or 1g daily up to 6 months or as long as needed