Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are now believed to be variants of the same condition, distinct from erythema multiforme. SJS/TEN is a rare, acute, serious, and potentially fatal skin reaction in which there is sheet-like skin and mucosal loss. Using current definitions, it is nearly always caused by medications.
SJS/TEN is a very rare complication of medication use (estimated at 1–2/million each year for SJS, and 0.4–1.2/million each year for TEN).
Anyone on medication can develop SJS/TEN unpredictably.
It can affect all age groups and all races.
It is slightly more common in females than in males.
It is 100 times more common in association with human immunodeficiency virusinfection (HIV).
Genetic factors are important.
There are HLA associations in some races to anticonvulsants and allopurinol.
Polymorphisms to specific genes have been detected (eg, CYP2C coding for cytochrome P450 in patients reacting to anticonvulsants).
More than 200 medications have been reported in association with SJS/TEN.
It is more often seen with drugs with long half-lives compared to even a chemically similar related drug with a short half-life. A half-life of a medication is the time that half of the delivered dose remains circulating in the body.
The medications are usually systemic (taken by mouth or injection) but TEN has been reported after topical use.
No drug is implicated in about 20% of cases
SJS/TEN has rarely been associated with vaccination and infections such as mycoplasmaand cytomegalovirus. Infections are generally associated mucosal involvement and less severe cutaneous disease than when drugs are the cause.
Nonsteroidal anti-inflammatory drugs (NSAIDs) (oxicam type mainly).
Causes
SJS/TEN is a rare and unpredictable reaction to medication. The mechanism has still not been understood and is complex.
Drug specific CD8+ cytotoxic lymphocytes can be detected in the early blister fluid. They have some natural killer cell activity and can probably kill keratinocytes by direct contact. Cytokines implicated include perforin/granzyme, Fas-L and tumour necrosis factor alpha (TNFα).
There are probably two major pathways involved:
Fas-Fas ligand pathway of apoptosis has been considered a pivotal step in the pathogenesis of TEN. The Fas ligand (FasL), a form of tumour necrosis factor, is secreted by blood lymphocytes and can bind to the Fas ‘death’ receptor expressed by keratinocytes.
Granule-mediated exocytosis via perforin and granzyme B resulting in cytotoxicity (cell death). Perforin and granzyme B can be detected in early blister fluid and it has been suggested that levels may be associated with disease severity.
Clinical features
SJS/TEN usually develops within the first week of antibiotic therapy but up to 2 months after starting an anticonvulsant. For most drugs the onset is within a few days up to 1 month.
Before the rash appears, there is usually a prodromal illness of several days duration resembling an upper respiratory tract infection or 'flu-like illness. Symptoms may include:
Fever > 39 C
Sore throat, difficulty swallowing
Runny nose and cough
Sore red eyes, conjunctivitis
General aches and pains.
There is then an abrupt onset of a tender/painful red skin rash starting on the trunk and extending rapidly over hours to days onto the face and limbs (but rarely affecting scalp, palms or soles). The maximum extent is usually reached by 4 days.
The skin lesions may be:
Macules — flat, red and diffuse (measles-like spots) or purple (purpuric) spots
Diffuse erythema
Targetoid — as in erythema multiforme
Blisters — flaccid (ie, not tense).
The blisters then merge to form sheets of skin detachment, exposing red, oozing dermis. The Nikolsky sign is positive in areas of skin redness. This means that blisters and erosionsappear when the skin is rubbed gently.
Mucosal involvement is prominent and severe, although not forming actual blisters. At least 2 mucosal surfaces are affected including:
Eyes (conjunctivitis, less often corneal ulceration, anterior uveitis, panophthalmitis) — red, sore, sticky, photosensitive eyes
Lips/mouth (cheilitis, stomatitis) — red crusted lips, painful mouth ulcers
Pharynx, oesophagus — causing difficulty eating
Genital area and urinary tract — erosions, ulcers, urinary retention
Upper respiratory tract (trachea and bronchi) — cough and respiratory distress
Gastrointestinal tract — diarrhoea.
The patient is very ill, extremely anxious and in considerable pain. In addition to skin/mucosal involvement, other organs may be affected including liver, kidneys, lungs, bone marrow and joints.
Complications of SJS/TEN
SJS/TEN can be fatal due to complications in the acute phase. The mortality rate is up to 10% for SJS and at least 30% for TEN.
During the acute phase, potentially fatal complications include:
Dehydration and acute malnutrition
Infection of skin, mucous membranes, lungs (pneumonia), septicaemia (blood poisoning)
Acute respiratory distress syndrome
Gastrointestinal ulceration, perforation and intussusception
Shock and multiple organ failure including kidney failure
Thromboembolism and disseminated intravascular coagulopathy.
Diagnose
SJS/TEN is suspected clinically and classified based on the skin surface area detached at maximum extent.
SJS
Skin detachment < 10% of body surface area (BSA)
Widespread erythematous or purpuric macules or flat atypical targets
Overlap SJS/TEN
Detachment between 10% and 30% of BSA
Widespread purpuric macules or flat atypical targets
TEN with spots
Detachment > 30% of BSA
Widespread purpuric macules or flat atypical targets
TEN without spots
Detachment of > 10% of BSA
Large epidermal sheets and no purpuric macules
The category cannot always be defined with certainty on initial presentation. The diagnosis may therefore change during the first few days in hospital.
Treatment
For further details, see Stevens Johnson syndrome / toxic epidermal necrolysis: nursing management.
Care of a patient with SJS/TEN requires:
Cessation of suspected causative drug(s) — the patient is less likely to die and complications are less if the culprit drug is on or before the day that blisters/erosionsappear
Hospital admission — preferably immediately to an intensive care and/or burns unit with specialist nursing care, as this improves survival, reduces infection and shortens hospital stay
Consider fluidised air bed
Nutritional and fluid replacement (crystalloid) by intravenous and nasogastric routes — reviewed and adjusted daily
Temperature maintenance — as body temperature regulation is impaired, patient should be in a warm room (30–32C)
Pain relief — as pain can be extreme
Sterile handling and reverse isolation procedures.
Skin care
Examine daily for extent of detachment and for infection (take swabs for bacterialculture).
Topical antiseptics can be used (eg, silver nitrate, chlorhexidine [but not silver sulfadiazine as it is a sulfa drug])
Dressings such as gauze with petrolatum, non-adherent nanocrystalline-containing silvergauze or biosynthetic skin substitutes can reduce pain.
Avoid using adhesive tapes and unnecessary removal of dead skin; leave the blister roof as a ‘biological dressing’.
May require intubation and mechanical ventilation if trachea and bronchi are involved
Urinary care
Catheter because of genital involvement and immobility
Culture urine for bacterial infection
General
Psychiatric support for extreme anxiety and emotional lability
Physiotherapy to maintain joint movement and reduce risk of pneumonia
Regular assessment for staphylococcal or gram negative infection
Appropriate antibiotic should be given if infection develops; prophylactic antibiotics are not recommended and may even increase the risk of sepsis
Consider heparin to prevent thromboembolism (blood clots).
The role of systemic corticosteroids (cortisone) remains controversial. Some clinicians prescribe high doses of corticosteroids for a short time at the start of the reaction, eg prednisone 1–2 mg/kg/day for 3–5 days. However concerns have been raised that they may increase the risk of infection, impair wound healing and other complications, and they have not been proven to have any benefit. They are not effective later in the course of the illness.
Case reports and small patient series have reported benefit from active adjuvant treatments delivered during the first 24–48 hours of illness. As SJS/TEN is fortunately a rare condition, controlled trials of therapies in large numbers of patients are difficult.
Ciclosporin 3–5 mg/kg/day is reported to reduce mortality by 60% compared to patients with similar SCORTEN score on admission that were not treated with ciclosporin.
Intravenous immunoglobulin (IVIG) 2–3 g/kg given over 2–3 days
Plasmapheresis.
Thalidomide, trialled because of its anti-TNFα effect, increased mortality, and should not be used.
Prevention
People who have survived SJS/TEN must be educated to avoid taking the causative drug or structurally related medicines as SJS/TEN may recur. Cross-reactions can occur between:
The anticonvulsants carbamazepine, phenytoin, lamotrigine and phenobarbital
Beta-lactam antibiotics penicillin, cephalosporin and carbapenem
In the future, we may be able to predict who is at risk of SJS/TEN using genetic screening.
Allopurinol should be prescribed for good indications (eg, gout with hyperuricaemia) and commenced at low dose (100 mg/day), as SJS/TEN is more likely at doses > 200 mg/day.
