Stevens-Johnson Syndrome / Toxic Epidermal Necrolysis
Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe, acute, and typically drug-induced mucocutaneous reactions characterised by widespread blistering, epithelial sloughing, and multisite mucositis.
This updated UKMLA guide to SJS and TEN is based on BAD guidelines, which cover types, causes, syptoms, diagnosis, and management.
Definition and Types
SJS/TEN represent a single disease severity spectrum, classified according to the disease extent, based on % of body surface area with epidermal detachment:
| Type / name | Body surface area with epidermal detachment* |
|---|---|
| SJS | <10% |
| SJS-TEN overlap | 10-30% |
| TEN | >30% |
*The % of body surface area involved is estimated using the Lund and Browder chart
In short, SJS is the less extensive form, and TEN is the more extensive and severe form.
Pathophysiology
The hallmark of SJS/TEN is widespread epithelial keratinocyte apoptosis and necrosis → separation of the epidermis from the underlying dermis → blistering and epidermal detachment
This is mediated by CD8+ cytotoxic T cells (which attack keratinocytes).
Causes and Risk Factors
SJS/TEN is primarily a drug-induced reaction (~85% cases).
Most common causative drugs:
- Allopurinol
- Anti-epileptics (carbamazepine, lamotrigine, phenytoin, phenobarbital)
- Sulfa drugs (e.g. sulfamethoxazole, sulfasalazine)
- Nevirapine
- Oxicam NSAIDs (e.g. piroxicam, meloxicam, and tenoxicam)
Rarely, infections can trigger SJS/TEN – most notably Mycoplasma pneumoniae
Clinical Features
SJS/TEN is generally preceded by a prodromal illness (fever, malaise, coryzal symptoms)
| Cutaneous features | Skin pain (and cutaneous tenderness) is a very prominent early feature
Initial lesions:
Progression:
+ve Nikolsky sign: skin is extremely fragile, such that minimal shearing forces will cause the epidermis to peel away |
| Mucosal features | Mucosal involvement is a hallmark of SJS/TEN and is almost universally seen
|
| Systemic features |
|
SJS vs erythema multiforme major (EMM)
By lesion appearance:
- SJS → flat atypical targets typically starting on the upper torso, proximal limbs and face
- EMM → typical targets or raised atypical targets predominantly localised on the limbs and extremities
By trigger
- SJS → drugs
- EMM → HSV reactivation
Complications
Acute complications arise from loss of the normal skin barrier:
- Secondary infection and sepsis (most common cause of death)
- Fluid loss, dehydration and hypovolaemic shock
- Hypothermia
- Respiratory compromise
- Organ dysfunction (e.g. AKI)
Investigation and Diagnosis
SJS/TEN is primarily a clinical diagnosis supported by clinical history and physical signs:
- It is important to elicit a detailed medication use history over the past 2 months
- Enquiry for previous drug allergies
- Prognostic scoring with SCORTEN must be calculated within the first 24 hours
To confirm the diagnosis, 2 skin biopsies are routinely taken:
- Routine histology: shows variable epidermal damage, ranging from individual keratinocyte apoptosis to confluent epidermal necrosis, with basal cell vacuolar degeneration and subepidermal blister formation
- Direct immunofluorescence: used to exclude autoimmune blistering disorders (e.g. bullous pemphigoid, pemphigus vulgaris)
- In SJS/TEN, direct immunofluorescence is negative
Other routine investigations:
- Clinical photographs of the skin
- Blood tests (FBC, ESR, CRP, U&E, magnesium, phosphate, glucose, LFT, coagulation study, mycoplasma serology)
- Skin swabs for microbiology (to monitor for secondary infections)
- Chest X-ray (to check for pulmonary manifestations or pneumonitis)
Management
ALL suspected SJS/TEN cases must be referred immediately to a specialised MDT (with dermatology and plastic surgery)
- Patients with >10% body surface area epidermal detachment (i.e. likely SJS-TEN overlap or TEN) must be admitted without delay to a specialised ICU or a burn centre.
Key management principles:
| Immediate action | Immediate discontinuation of any potential causative drug |
| Supportive care | Mainstay of management is supportive care:
Adjunct medications
DO NOT routinely give systemic antibiotics – ONLY to be given if there are active clinical signs of infection. |
| Skin and mucosal management | Skin care:
Mouth care:
Eye care:
If respiratory compromise or hypoxaemia occurs → fibreoptic bronchoscopy to clear sloughed bronchial epithelium |
| Immunosuppressive treatment | DO NOT offer immunosuppressive treatment, including:
|