Epidermal Necrolysis

Severe immune-mediated epidermal necrosis and desquamation at ⩾2 distinct sites that is divided by extent of skin involvement into:

Stevens-Johnson Syndrome
<10% BSA.
SJS/TEN Overlap syndrome
10-30% BSA.
Toxic Epidermal Necrolysis
>30% BSA.

Epidemiology and Risk Factors

Epidemiology:

Annual incidence ~5/1,000,000.

Risk factors:

↑ Age
Female sex
HIV
Connective tissue disease
Malignancy

Pathophysiology

T-cell mediated reaction:

Drug-specific CD8+ T-cells are activated
Cytotoxic proteins released
Epidermal necrolysis released

Aetiology

Precipitants include:

Medications
Most cases are due to an idiosyncratic reaction to certain families of medications that:
- Are usually commenced between 1 week and 1 month prior
- Include:
  - Antibiotics
    - Amoxacillin/ampicillin
    - Fluoroquinolones
    - Sulfamethoxazole
    - Doxycycline
    - Rifampicin
  - Antiepileptics
    - Carbamazepine
    - Lamotrigine
    - Phenobarbital
    - Phenytoin
  - NSAIDs
Infection
- Mycoplasma
Idiopathic

Assessment

Identify the potential causative agents
Assess the degree of skin loss

Assessment principles are similar to Burns.

History

Prodromal symptoms:

Malaise
Fever
Sore throat
Conjunctivitis

Examination

Mucocutaneous features:

Lesions typically begin on the face and thorax
Symmetrically distributed
Typically begin as flaccid bullae
Progress to “sheet-like” detachment of skin
Mucosal involvement in 80%
Genital involvement in 70%
Corneal involvement in >60%

The Nikolsky sign is positive if epidermal detachment can be extended with gentle lateral pressure.

Investigations

Bedside:

Laboratory:

Imaging:

Other:

Skin biopsy

Diagnostic Approach and DDx

Disease occurs in two phases:

Acute phase
5-7 period of worsening desquamation and mucositis. Risk of:
- Hypovolaemia
  - Haemoconcentration
  - AKI
- Sepsis
- Multiorgan failure
- Death
Chronic phase
Convalescence and recovery.

Key differentials:

Erythema multiforme
Drug eruptions

Management

Treat precipitant
Transfer to burns centre

Resuscitation and supportive care has many similarities to burns, and is covered under Burns.

Resuscitation:

A
- Intubation
  May be required if mucosal involvement

Specific therapy:

Pharmacological
- Cease offending agent
Procedural
Physical
- Specific ocular care
  - Ocular rinses
  - Lubricants
  - Conjunctival adhesion separation
    - Glass rod
    - Forceps
- Specific genital care
  Risk of fibrosis with adjacent skin edges, consider:
  - Topical corticosteroid
  - Silicone vaginal dilators
  - IDC placement
  - Regular foreskin retraction

Supportive care:

D
- Multimodal analgesia
F
- Volume resuscitation
  Prevent hypovolaemia.
G
- Early EN
  May need 25-30kcal/kg/day due to ↑ metabolism.
- Stress ulcer prophylaxis
H
- Thromboprophylaxis
I
- Wound dressings
  - Non-adhesive

Disposition:

Preventative:

Marginal and Ineffective Therapies

Systemic immunomodulation therapy has limited evidence, however there is potential benefit from may:

Pulse steroids
May be more effective when commenced early in disease onset.
IVIG
1-2g/kg/day.
Ertanercept
TNF-α inhibition.

Non-recommended agents include:

Thalidomide

Anaesthetic Considerations

Complications

Death
~25%, with ↑ mortality with ↑ desquamation.
B
- Lung injury
  Direct bronchial sloughing.
- HAP/VAP
F
- AKI
  - Pre-renal
G