Stevens-Johnson Syndrome

Stevens-Johnson syndrome (SJS) is a severe, T-cell mediated mucocutaneous reaction characterised by widespread epidermal necrosis involving less than 10% of body surface area (BSA).

• Incidence is 2 to 7 per million per year. Mortality is about 5 to 10% (SCORTEN dependent).
• Drugs account for most cases: allopurinol (HLA-B*58:01), carbamazepine (HLA-B*15:02 in Han Chinese, Thai and Malay populations), phenytoin, lamotrigine, oxcarbazepine, nevirapine, sulfonamides (sulfamethoxazole), aminopenicillins, NSAIDs (oxicams), and phenobarbital. Onset 4 to 28 days after starting a new drug.
• Infectious triggers: Mycoplasma pneumoniae, HSV (particularly in children).
• Higher risk with HIV, malignancy, and lupus.

• Prodrome of fever, malaise, sore throat, and eye discomfort for 1 to 3 days.
• Painful dusky or purpuric macules and atypical targets that coalesce, then flaccid blisters and epidermal detachment (under 10% BSA). Nikolsky sign positive.
• Severe mucosal erosions of the mouth, eyes (conjunctivitis, pseudomembranes), genitalia, and respiratory tract.
• Complications: sepsis, hypovolaemia, acute kidney injury, pneumonitis, corneal scarring and blindness, vulvovaginal and urethral synechiae, nail loss, and chronic dry eye.

• Clinical diagnosis supported by biopsy: full thickness epidermal necrosis with sparse dermal infiltrate; DIF negative.
• Severity score: SCORTEN (age over 40, malignancy, heart rate over 120, BSA over 10%, urea over 10 mmol/L, glucose over 14 mmol/L, bicarbonate under 20 mmol/L); each item scores 1.
• Drug causality using ALDEN. Cultures, chest X-ray, Mycoplasma PCR and serology, HSV PCR.
• Exclude erythema multiforme major, DRESS, staphylococcal scalded skin syndrome, generalised bullous fixed drug eruption, and AGEP.

• Immediately stop all suspect drugs. Admit to a burns unit, ICU, or specialist centre.
• Supportive: warmed environment, fluid resuscitation (about two thirds of burns requirement), enteral nutrition, analgesia, non-adherent dressings (silver or silicone mesh), sterile handling, and thromboprophylaxis.
• Antibiotics only for proven infection; avoid prophylactic use.
• Daily ophthalmology review: lubricants, topical steroid drops, lysis of synechiae, amniotic membrane transplantation in severe cases.
• Immunomodulation (evidence mixed): ciclosporin 3 to 5 mg/kg/day for 7 to 10 days, or etanercept 25 to 50 mg SC single dose, or IVIG 1 g/kg/day for 3 days (variable benefit); short course systemic corticosteroids (methylprednisolone 1 to 2 mg/kg for 3 days) in some centres.
• Long term: dry eye, strictures, genital adhesions, psychological support, allergy card, family HLA testing counselling, and drug avoidance.