Background
- Rare, acute, serious, potentially life-threatening skin Rxn
- Epidermal slouching, blistering and mucosal loss
- SJS / TEN - same pathology along a severity spectrum
- Similar to but distinct from Erythema Multiforme (EM)
Epidemiology
- SJS: 1-2 million annually in US
- TEN: 0.4-1.2 M annually in US
- All ages & races (x100 in HIV)
- ↑ in the elderly, F > M = 2:1
- HLA-B*1502, HLA-B*5801 (allopurinol-induced)
Causes
- SJS/TEN are mainly caused by drugs
- > 200 meds. are associated
- In 15% of cases no culprit drug is identified
- Also infections (particularly in children)
- Idiopathic
Commonly implicated
| Infection | Drugs |
|---|---|
| Mycoplasma | Sulphonamides |
| CMV | NSAIDs |
| HSV | Allopurinol |
| Penicillin | |
| Anticonvulsants | |
| Paracetamol | |
| Β-lactam antibiotics |
Clinical
Symptoms
- Onset is usually 7-10 days trigger
- Latency varies:
- Antibiotic assoc. SJS/TEN 1 week
- Anticonvulsants may be two months
- Prodromal "flu-like" URTI
- Fever, cough, rhinitis, sore throat, conjunctivitis, myalgia
- Then abrupt onset rash:
- Starts on trunk
- Spreading (over hrs/days) to face and limbs
- Rash max. extent in 4 days
Signs
- Erythema, targetoid
- Macules or blisters
- Blisters merge - skin detachment - red oozing dermis
- Nikolsky's sign positive (rub skin = exfoliation)
- ≥2 mucosal surfaces affected
- Eyes
- Mouth
- Oesophagus
- Genitals
- Lower GI
Classification
SJS/TEN classified based on % epidermal detachment & type of skin lesion
- SJS: <10% BSA, purpuric macules or flat targetoid lesions
- SJS-TEN: 10-30% BSA, purpuric macules or flat targetoid lesions
- TEN with spots: >30% BSA, purpuric macules or flat targetoid lesions
- TEN without spots: >10% BSA, large epidermal sheets, no purpuric macules
SCORTEN
Illness severity score to predict mortality. One point for each criterion at time of admission:
Clinical
- Age >40
- Malignancy
- HR >120
- >10% epidermal detachment
- Serum urea >10mmol/L
- Serum glucose >14mmol/L
- Serum Bicarb. <20mmol/L
SCORTEN mortality
| SCORTEN 0-1 | >3.2% |
| SCORTEN 2 | 12% |
| SCORTEN 3 | >35% |
| SCORTEN 4 | >58% |
| SCORTEN 5 | >90% |
Investigations
SJS / TEN is a clinical Dx
- FBC (↓Hb, ↓WCC, ↓neutrophils [bad prognostic], ↑eosinophils)
- U&E (electrolyte balance)
- Amylase
- VBG / Bicarb
- LFTs (50% ↑, 50% have ↓albumin)
- Glucose ↑
- Skin swabs
- CXR (? mycoplasma)
- Urine dipstick (50% mild proteinuria)
- CRP ↑ (why wouldn't it be?)
- Coag. profile
- Mycoplasma serology
- ANA
- ENA
- Complement levels
- Direct immunofluorescence (negative)
- Serum granulysin (↑ in first few days of drug eruption)
Differential Dx
- Erythema multiforme major
- SSSS
- Pemphigus vulgaris
- Bullous pemphigoid
- Generalised bullous drug Rxn
- Acute graft-vs-host disease
Management
- Cessation of suspected causative drugs – better prognosis if drug is stopped before blisters/erosions appear
- Supportive management to maintain haemodynamic stability:
- Admit – ideally to ICU or burns unit
- Analgesia
- Sterile handling and reverse isolation procedures to prevent infection
- Temperature maintenance – warm rooms 30-32°C
- Nutritional and fluid replacement – IV or NG
- Prophylactic anticoagulation
- Specialist skin-care nursing for topical therapy and dressings
- Inconclusive evidence on IVIg, steroids, ciclosporin, cyclophosphamide, plasmapheresis and anti-TNFα
Complications
Acute
- Hypothermia, dehydration, malnutrition
- Electrolyte imbalance, infection, sepsis
- ARDS, AKI, GI ulceration, perforation
- Intussusception, shock, organ failure
- Resp. involvement (bronchiolitis, bronchiectasis)
- Thromboembolism and DIC
Chronic
- Scarring, hyper/hypopigmentation, anoychia
- Joint contractures
- Ocular sequelae (blindness, conjunctivitis, corneal ulcers, symblepharon, ectropion, entropion, trichiasis, synechiae)
- Bronchiolitis obliterans
- Oesophageal stricture, urogenital adhesions
- Psychological sequelae