Steven-Johnson Syndrome and Toxic Epidermal Necrolysis

Steven-Johnson Syndrome (SJS) - the rare dermatological emergency with a prevalence of 1:100,000.

SJS is a vesiculobullous form of erythema multiforme affecting the skin, mouth, eyes and genitalia. Area of affected <10% - SJS; 10-30% - overlap syndrome; >30% Toxic Epidermal Necrolysis (TEN).

2. The aetiology is mainly drug reactions in supseptible HLA groups. The drugs mediate expression of various cytokines which trigger keratinocyte apoptosis and thus exfoliation of epidermis.

3. Some of the common medications known for causing SJS/TEN include:

anti-gout: allopurinol

antibiotics: cotrimoxazole, aminopenicillins, cephalosporins, quinolones, TMP-SFX

antiretrovirals

sulphur-containing drugs

phenytoin

phenobarbital

4. Patient presents with enlarging red-purple macules/papules/bullae at the conjunctiva, mucous membrane, nares and genital regions. The skin lesion enlarges within 2 days. There are flat, atypical target lesions or purpuric macules distributed on the trunk or widespread. The extent of involvement determines the classification of disease. Nikolsky sign (applying pressure on skin) may be positive with shearing off of epidermis.

5. Patient's history include cutaneous eruption that occurs within 8 weeks of drug initiation. Prior to the skin lesion, patient may complain of influenza-like symptoms (fever, cough, fatigue).

6. Delayed management may result in complications such as:

blindness due to corneal ulceration

haemorrhagic crusting at sites of stomatitis

dehydration due to poor oral intake (pain)

breathing difficulties due to thick mucopurulent sputum

difficulty urinating due to urethral involvement

7. Diagnosis is based on clinical presentation of the lesion. Laboratory tests are mainly to assess complications. A FBC and C+S may be ordered if suspected infection. Chest x-ray may show pulmonary involvement. If the diagnosis is uncertain, a skin biopsy may be performed. Serum electrolytes, urea, glucose, bicarbonate should be monitored to determine organ function and fluid balance.

8. The main principle of treatment is to WITHDRAW the drug and provide supportive care and management of secondary conditions. Referral should be made to ICU or burn unit. IVIG can be administered in severe cases. Recent studies by Paradisi A. et al (2014) suggest a role of TNF-a inhibitors (etanercept) to be efficacious in treating SJS/TEN. Other agents such as cyclosporine, cyclophosphamide and plasmapheresis may also be effective. Corticosteroids (prednisone) use is controversial due to risk of sepsis, but studies suggest that its usage is beneficial in early stages of disease.

9. Supportive treatments to improve QoL:

antihistamines to reduce pruritus

oral rinsing to relief oral lesions

provide soft diet and plenty of liquid for hydration

antibiotics cover if secondary infections

vitamin A to protect the eye against lacrimal hyposecretion

monitor the eyes for any worsening

catheterisation if urethral involvement

prophylactic anticoagulation

non-adhesive wound dressing

10. SCORETEN scale is used to predict the mortality risk and prognosis. The oral lesion may continue for several months. Permanent scarring and corneal abnormalities may occur in 20% of the patients. Late withdrawal of causative drug has a less favourable outcome.

11. The differential diagnosis include:

SJS-TEN spectrum

toxic erythema

pemphigus/pemphigoid

haemorrhagic fevers

staphylococcal scalded-skin syndrome