Erythema Multiforme

Question 1

Define Erythema Multiforme

Answer 1

Acute mucocutaneous inflammatory hypersensitivity condition that is self-limiting but often relapsing, presenting as target lesions or raised oedematous papules

Question 2

Aetiology of Erythema Multiforme

Answer 2

Usually infection: HSV and Mycoplasma | EBV, CMV, Histoplasmosis, Kawasaki disease, herpes zoster, gardnerella
Drugs: aminopenicillins, docetaxel, TNF-alpha inhibitors, antimalarials, oral contraceptives, anticonvulsants and lidocaine, sulphonamides
Vaccinations: hep B, smallpox, varicella, meningococcal, HPV and hantavirus

Question 3

What is Stevens-Johnson syndrome

Answer 3

severe macular lesions that coalesce, resulting in epidermal blistering, necrosis and sloughing, affecting<10% of the body surface area

Question 4

What is Toxic epidermal necrolysis (TENS)

Answer 4

severe macular lesions that coalesce as in SJS but affect more than 30% of the total surface body area

Question 5

Distinguish between erythema multiforme minor and major

Answer 5

EM minor: Acral distribution WITHOUT involvement of mucosal sites and involving <10% total body surface area

EM major: Acral distribution and involvement of 1 or more mucosal sites and <10% total body surface area

Question 6

Symptoms of erythema multiforme

Answer 6

Prodromal symptoms of URTI

Skin lesions (Sudden appearance | Itching/burning/painful skin lesions | Self-limiting | May fade to leave pigmentation | Often starts on hands)

Question 7

Signs of Erythema Multiforme on examination

Answer 7

Target lesions
- 3 zones: red rim, clearance zone and central blister/erosion
Targetoid lesions
- Erythematous papules without a clearance zone
Mucosal erosions (EM major)

Question 8

What are the specific signs/symptoms for the following diseases that cause erythema multiforme:
Herpes simplex
Mycoplasma pneumonia
Hep B

Answer 8

Herpes Simplex-related disease → Recurrent disease | Clustered vesicles on an erythematous base

Mycoplasma pneumonia → Ronchi, rales +/- wheeze | Red tympanic membrane

Hepatitis B infection → Hepatomegaly

Question 9

Investigations for Erythema Multiforme

Answer 9

Clinical diagnosis + investigations for cause

FBC: abnormal WCC
Serology: HSV, cold-haemagglutination (myocplasma)
PCR: varicella