ERYTHEMA MUTIFORME MINOR
DEFINITION:
An acute mucocutaneous hypersensitivity reaction resulting in the
formation of symmetric, discrete, red papules and plaques of
variable morphology which tend to recur.
EPIDEMIOLOGY:
- incidence: 1/1,000-10,000
- age of onset:
- peaks between 20-40 years of age
- 20% of cases occur in children
- risk factors:
- exposure to triggers (see below)
- winter, early spring
PATHOGENESIS:
- exposure to trigger -> host immune response to a foreign
antigen -> EM
- HSV-induced EM:
- accounts for 15-63% of cases of EM Minor
- associated with recurrent HSV and occurs about 10 days
following the onset of HSV; associated with each outbreak of
HSV
- not associated with a primary HSV infection
CLINICAL FEATURES:
- occurs in about 30% of cases
- flu-like symptoms:
- sore throat, headache, arthralgias, myalgias, fever
- lasts 1-2 weeks before the onset of the skin manifestations
in 33% of patients
- may begin within 1-3 weeks after starting a new drug
2. Skin Manifestations
- acute onset of rash which is self-limiting
- represents the evolution of fixed skin lesions through
multiple morphologic stages and not the occurence of several
different types of skin lesions
- evolves from macules to papules to plaques over 3-5 days
rather than over hours
- skin lesions may vary between patients, within a
patient, or between episodes
- location:
- commonly affects the distal extremities involving the
extensor surfaces of the arms, legs, elbows, knees, dorsum
of hands and feet, and nailfolds
- areas usually spared include the scalp, face, neck,
trunk, perineum, palms, and soles
- tends to spread from the extensor surfaces of the
extremities to the flexural surfaces and then to the trunk
- propensity for areas exposed to light and/or physical
trauma
2. Rash
2. Others
- mild cutaneous blistering may occur
- edema
- Koebners phenomenon
3. Mucous Membrane Manifestations
- occur in about 60% of cases
- mild involvement usually restricted to the mouth:
- erythema and edema
- aphthous-like shallow oral ulcerations
- may occur simultaneously with, precede, or follow the
cutaneous manifestations
- there may also be mild conjunctival injection
INVESTIGATIONS:
- elevated ESR, WBC, platelets, circulating immune complexes
2. Serology
- for various bacteria and viruses
3. Skin Biopsy
MANAGEMENT:
REFERENCES:
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