Erythrema Multiforme

Question 1

Define Erythema multiforme

Answer 1

acute, mild, self-limiting but often relapsing mucocutaneous inflammatory condition

Round lesions with outer ring of erythema and blisters in the centre with normal skin tone

often associated with infection and some medications

can be on skin-anywhere, or mucous membranes-mainly mouth and nose

EM minor-only skin
EM major-skin and mucuous

Question 2

Aetiology and risk factors of Erythema multiforme

Answer 2

Hypersensitivity pattern found in susceptible people-mainly secondary to infection
Most common-HSV and mycoplamsa
But also Hep B, CMV, EBV, Kawasaki, Varicella

also common enough with aminopenicillins, TNFa inhibs, antimalarial, oral contraceptive and lidocaine injections

risk factors:
Prior Hx of EM
HSV-main
mycoplasma
Drugs
Other infection listed above
IV risk (HIV, Hep B)
FHx

Question 3

epistemology of Erythema multiforme

Answer 3

Unkown, but thought to be common-nearly 30% of patients
peak in 30’s
drugs and HSV are by far leading cause

Question 4

Signs and Sx of Erythema multiforme

Answer 4

Both minor and major occupy less than 10% of body area
Hx-focus on infection, especially HSV, mycoplasma (lung)
Good DH

Pt appear a few days after trigger-and the lesion can resemble target lesions (spared centre)
rapid onset, decrease over 7 days
discomfort but NOT itchy initially (until heal)
Oral mucosal-painful

typically-round, outer erythema ring with centre of blisters but normal skin tone
Typically appear in the limbs/extremities
inspect mucous membranes for EM major

Question 5

Investigations of Erythema multiforme

Answer 5

Usually fully clinical-
but can order test to find the aetiology
FBC/U&E-infection signs

HSV antigen
PCR
cold-heammoglutinase serology-identify Mycoplasma

CXR-varies