Drug reactions (SJS, TEN) Flashcards
Define Stevens-Johnson syndrome and TEN.
SJS is a severe skin detachment with mucocutaneous complications. It is an immune reaction to foreign antigens. SJS is a less severe manifestation of TEN as classified by % skin involvement: SJS is < 10% TBSA and TEN is > 30% TBSA .
May have skin and mucosal necrosis with systemic toxicity.
What is the pathophysiology of SJS?
Causes include drugs/infections
Pathophysiology may start up to 3 weeks before the rash shows
How common is SJS?
90% due to drug reactions
Affects all age groups
x100 more common in HIV
HLA association in some to allopurinol and anticonvulsants
Is SJS or TEN more common?
SJS = < 10% of cases
TEN = > 30% of cases
Overlap = 10-30%
What are some drug causes of SJS/TEN?
- Antibiotics in 40% - beta lactams (penicillins, cephalosporins), sulphonamides (cotrimoxazole)
- Allpurinol
- AEDs - phenytoin, carbamazepine, lamotrigine, phenobarbitone
- NSAIDs
- Paracetamol
- Nevirapine (NNRTI)
10% no drug reaction association
What are the clinical features of SJS? What is the natural progression of skin lesions?
- Prodromal flu-like symptoms
- Painful erythematous rash with mucosal involvement
- Abrupt onset of lesions on trunk > face/limbs
- Progression: Macules -> papules/target lesions -> blisters/bullae -> epidermal detachment -> mucosal involvement
- Atypical targetoid lesions
- Blisters merge
- Sheets of skin detachment - Nikoslky +ve
Where does the rash present in SJS/TEN?
Upper torso, proximal limbs, and face
Which mucosal surfaces may be invovled in SJS/TEN?
Eyes, lips, mouth, pharynx, oesophagus, gastrointestinal tract, kidneys, liver, anus, genital area, or urethra
What do investigations show in SJS/TEN?
Biopsy -
SJS: histopathology shows epithelial necrosis and few inflammatory cells
TEN: Full thickness epidermal necrosis with subepidermal detachment
FBC - anaemia, lymphopenia, neutropenia, eosinophilia
LFTs - mildly raised liver enzymes (30%)
Renal profile - occasional derangement in renal function
Cultures - skin, urine, blood, sputum every 3 days.
Other:
U&Es - may be deranged
CXR - ?pneumonitis
Coagulation - ?DIC
Direct immunofluorescence - exclude autoimmune blistering condition, should be negative in SJS/TEN
What is the management of SJS/TEN?
Stop all medications - unless absolutely necessary
Admit to ITU/burns unit - side room with controlled temperature and humidity
Refer to dermatology and ophthalmology
MDT approach
Supportive treatment:
- Careful handling
- Pain management - paracetamol/opioids; avoid NSAIDs
- Fluid monitoring
- NG tube
- Aspirate/express blisters
- Catheterise +/- tampon - avoids strictures
- Dietician review
NB: avoid antibiotics unless necessary
Topical:
- Non adherent dressings
- Steroids - mild steroids for face and flexures, potent steroids for body
- Eye care - lubricant eye drops + chloramphenicol eye drops
- Oral care - anti-inflammatory + analgesic + topical anaesthetic
Systemic:
- Cyclophosphamide (1st line)
- IVIG
- Pulse high dose steroids/adalimumab (biologic) - 2nd line
When should you transfer a SJS/TEN patient to a burns unit?
TEN i.e. >30% TBSA
AND any of:
- Clinical deterioration
- Extension of epidermal detachment
- Sub epidermal pus
- Local sepsis
- Wound conversion
- Delayed healing
Describe some of the wound care techniques used in SJS/TEN.
Conservative (anti-shear strategy):
- Preserve detached epidermis as a biological dressing
- Limit dressing changes
- Use air-fluidised bed
- Non-adherent dressings +/- silver-impregnated dressing for antibacterial properties
- Absorptive dressings
- Drainage of wounds only for patient comfort;
- Clean with sterile water or dilute chlorhexidine
- Emollient to the whole epidermis
The surgical approach, in burn unit:
- Surgical debridement of detached epidermis
- Biological dressing, such as xenograft (pigskin), allograft (cadaver skin), or synthetic dressing.
- Non-adherent silver-impregnated dressing
Once the skin has regenerated (after about 2-3 weeks) - use a lot of emollients
What are the complications of SJS/TEN?
Extensive full thickness mucocutaneous necrosis in < 2-3days
What is the prognois with SJS/TEN?
Studies show up to 18% may have recurrence within 7yrs
Mortality rate is lower in children than adults
Most recover with some organ or ocular complications
SJS mortality 1-5%
TEN mortality 25-35%
Death usually due to sepsis, organ failure or cardiopulmonary complications.
What are the non-drug causes of SJS/TEN?
Infection
- URTI
- Pharyngitis
- Otitis media
- Mycoplasma pneumoniae
- Herpes
- EBV
- CMV
Vaccination
- Smallpopx
What is the diagnosis?
DRESS syndrome - drug reaction, eosinophilia, systemic symptoms = a specific, severe, unexpected reaction to a medicine, which affects several organ systems at the same time
What are the most common causes of DRESS?
