SJS & TEN

Severe, life-threatening mucocutaneous drug reactions characterized by extensive epidermal necrosis and detachment, accompanied by mucosal involvement and systemic symptoms.

Definition

They represent a clinical spectrum, differentiated by the extent of body surface area (BSA) detachment:
Condition
BSA Detachment
SJS
<10%
SJS/TEN overlap
10–30%
TEN (Weil’s Disease)
>30%

Aetiology

High-risk drugs

Drug Group
Examples
Anticonvulsants
Lamotrigine, Carbamazepine, Phenytoin
Allopurinol
Very common trigger
Sulfonamide antibiotics
Cotrimoxazole, Sulfasalazine
β-lactam antibiotics
Penicillin, Cephalosporins
NSAIDs (oxicams)
Piroxicam, Tenoxicam
Antiretrovirals
Nevirapine
Other triggers: infections (Mycoplasma pneumoniae), vaccines (rare).

Pathogenesis

  • Type IV (delayed) hypersensitivity reaction
  • Drug or metabolite interacts with keratinocyte surface antigens → activation of cytotoxic CD8+ T cells & NK cells
  • Release of granulysin, perforin, granzyme B, and Fas-FasL-mediated apoptosis
  • → Massive keratinocyte apoptosis → epidermal necrolysis
Granulysin is considered the main cytotoxic mediator.

Clinical presentation

Prodromal phase (1–3 days before rash)

  • Fever
  • Malaise
  • Sore throat
  • Cough
  • Arthralgia
  • Burning eyes

Cutaneous signs

  • Dusky-red macules or atypical target lesions
  • Rapid progression to bullae and epidermal detachment
  • Nikolsky sign positive (skin peels with pressure)
  • Pain > pruritus
notion image

Distribution

  • Trunk → face → generalized involvement
  • Palms/soles may be affected

Mucosal involvement (>90% cases)

A hallmark feature
  • Oral mucositis
  • Hemorrhagic crusting lips
  • Conjunctivitis, corneal ulceration
  • Genital erosions

Severity Indicators

  • Extensive necrolysis
  • Multiorgan involvement (renal, respiratory, GI)

Investigations

Clinical diagnosis based on:

  • Recent drug exposure
  • Typical mucocutaneous lesions — Conjunctivitis & Stomatitis
  • Positive Nikolsky sign & skin detachment

Investigations

Test
Purpose
CBC
Lymphopenia may occur
LFT, RFT
Evaluate organ involvement
Electrolytes
Assess fluid balance
Skin biopsy
Full-thickness epidermal necrosis

Management

Immediate withdrawal of causative drug

Most critical step — earlier cessation improves survival.

Supportive care (similar to burn management)

Aspect
Intervention
Fluid & electrolyte balance
IV fluids based on BSA loss — 10-20 cc/kg/IV RL
Wound care
Non-adhesive dressings
Temperature regulation
Warm environment
Nutrition
High-calorie support
Pain control
Opioids/analgesics
Infection prevention
Strict asepsis (no routine antibiotics)

Systemic therapy (specialist guided)

Evidence still evolving.
Options:
  • IVIG
  • Systemic corticosteroids (early phase)
  • Cyclosporine
  • TNF-α inhibitors (Etanercept) — promising results

Mucosal care

  • Ocular consult mandatory (risk of blindness)
  • Lubricants, topical antibiotics, amniotic membrane transplantation if needed