Erythema multiforme, SJS and TEN

Question 1

Describe this skin lesion

Answer 1

Itchy, maculopapular target lesions with 3 concentric zones:
1. Central dark red to purple area
2. Pale oedematous ring
3. Rim of erythema

Symmetrically distributed throughout the body
- Mainly: palms and soles, face, dorsum of hands, extensors of limbs

Question 2

Complications of erythema multiforme

Answer 2

1. Koebner phenomenon may occur
2. Mucosal involvement (25%) - oral cavity
3. Eye involvement - bilateral purulent conjunctivitis, increased lacrimation
4. Progression to Stevens-Johnson syndrome or worse toxic epidermal necrolysis
   - Greater mucosal involvement of 2 or more (mouth and lips, conjunctivae, nasopharynx, respiratory, gastrointestinal, genitourinary)

Question 3

What are the difference between erythema multiforme, Stevens-Johnson syndrome and TEN?

Answer 3

Spectrum of severity

Erythema multiforme
- targetoid skin lesion in absence of systemic illness or severe mucosal disease

SJS
- Widespread targetoid lesions, flat and atypical, confluent and develop large areas of blisters and epidermis detachment
- Purpuric
- Fever and systemic symptoms
- Affecting < 30% BSA

TEN
- Blistering with extensive skin detachment
- Cell poor, necrotic keratinocytes without satellite cell necrosis
- Affecting > 30% BSA

Question 4

What are the possible causes of erythema multiforme?

Answer 4

1. Infections
   - Tuberculosis - productive cough, apical chest signs
   - Streptococcal throat infection
   - Mycoplasma pneumoniae
   - Rickettsiae
   - Syphilis
   - Viruses: HSV, EBV, CMV, HIV, VZV, Hep A/B/C
   - Gastrointestinal: campylobacter, salmonella, yersinia
   - Fungal: coccidiomycosis, histoplasmosis, blastomycosis
   - Parasites: toxocara, toxoplasma
2. Sarcoidosis - lupus pernio, ILD
3. SLE - butterfly malar rash, arthritis
4. Polyarteritis nodosa - vasculitic skin lesions
5. GPA - nasal deformities, respiratory involvement
6. Malignancy - constitutional symptoms, cachexia
7. Myeloproliferative disease - hepatosplenomegaly, lymphadenopathy
8. Drugs (see subsequent card) - take detailed history

Question 5

What are the commonest drugs associated with erythema multiforme?

Answer 5

1. Penicillin and tetracyclines
2. Sulphonamides
3. Sulfonyureas (glipizide, gliclazide)
4. Anticonvulsants, barbiturates, phenobarbital, phenytoin
5. Carbamazepine (HLA 15:02)
6. Gold
7. NSAIDs
8. Salicylates
9. OCP
10. Allopurinol (HLA 58:01)