Erythema Multiforme
Basics
Basics
Basics
Description
Description
- A rash caused by a hypersensitivity reaction:
- May occur in response to various medications, infections, or other illness
- Erythema multiforme (EM) minor:
- Typical target lesions
- Edematous papules
- Usually distributed peripherally
- Benign, self-limited rash generally not associated with acute, serious illness
- EM major:
- Target lesions
- Edematous papules
- Also with peripheral distribution
- Involves 1 or more mucous membranes
- <10% total body surface area of epidermal detachment
- Differentiate from:
- Stevens–Johnson syndrome (SJS):
- Also <10% TBSA epidermal detachment
- Often widespread blisters over trunk and face
- Mucosal involvement
- Toxic epidermal necrolysis (TEN):
- >30% TBSA epidermal detachment
- EM is distinct from SJS and TEN
- Most often affects children and young adults (>50% younger than 20 yr)
- Males are affected more often than females
Etiology
Etiology
- Hypersensitivity reaction, probably transient autoimmune defect
- Herpes simplex virus (HSV) is the most common precipitant (>70%)
- Other causes include:
- Infection:
- Hepatitis C medications:
- Sulfa drugs
- Anticonvulsants
- Antibiotics
- Vaccines:
- Diphtheria–tetanus
- Hepatitis B
- Smallpox
- Malignancy
- Idiopathic
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