SJS and TEN

• Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN):

  • Rare, acute, and potentially fatal skin reactions which cause sheet-like skin detachment and mucosal loss
  • Both SJS and TEN are believed to be variants of the same condition that can be differentiated by the degree of skin and mucous membrane involvement
  • Caused by an immune complex mediated hypersensitivity reaction
  • Mostly, but not always caused by medications
• SJS and TEN can be differentiated by the degree of skin and mucous membrane involvement:

  • SJS has <10% TSBA involvement
  • SJS/TEN overlap has 10% to 30% TBSA involvement
  • TEN has >30% TBSA involvement
• Aetiology:

  • Results from an immune reaction to foreign antigens - pathophysiology not fully understood
  • Characterised by the detachment of the epidermis from the dermis - manifesting as dusky macular erythema, followed by blistering resulting from keratinocyte apoptosis
  • Around 75% of cases are caused by medications, 25% by infections and other causes
  • Usually develops in individuals who have started taking a new drug for 1 day - 1 month
• Risk factors:

  • Antibiotics - biggest risk with trimethoprim and other sulphonamide antibiotics
  • Anticonvulsant medications - carbamazepine, phenytoin
  • Recent infection - mycoplasma pneumonia is liked to SJS. Viral include herpes, EBV and CMV
  • Many other medications
  • SLE - likely caused by immune reactions with medicines used to treat
  • More common in HIV/AIDS patients
  • Radiotherapy
  • Certain HLA alleles - some alleles are associated with a SJS/TEN reaction to carbamazepine and allopurinol
• Typical symptoms:

  • Prodromal flu-like illness for several days before rash
  • Fever >39
  • Sore throat, odynophagia, dysphagia
  • Cough, runny nose
  • Sore red eyes, conjunctivitis
  • Arthralgia, malaise
  • Painful skin rash - starts at the trunk and extending rapidly over hours to days onto the face and limbs with blistering
  • Mucosal ulceration - eyes, lips, mouth, genitals
• Clinical findings:

  • Initially - tender dusky erythematous skin rash in clusters of macules and progresses to blistering
  • Blisters merge to form sheets of skin detachment (desquamation) - exposing red, oozing dermis
  • Nikolsky sign positive - epidermal layer easily sloughs off when pressure applies
  • Maximum extent is usually reached by 4 days
  • Mucosal involvement is prominent and severe - erosions or ulcerations of the eyes, lips, mouth, oesophagus, GI tract, kidneys, liver, anus, genital area or urethra
• Diagnosis:

  • Characteristic clinical presentation and a skin biopsy is sufficient to diagnose
  • Biopsy taken at the transition point of blistering can assess the level of desquamation
• Lab investigations:

  • FBC - anaemia, leucopenia/neutropenia
  • LFTs - mildly deranged, some develop hepatitis
  • U&Es - important to assess hypovolaemia and exclude renal failure
  • Glucose - assess for hypoglycaemia
  • Magnesium - low often seen in patients with skin loss
  • Phosphate - elevated or low levels suggest muscle damage
  • Urine dip - mild proteinuria
  • Blood cultures
  • ABG
  • CXR - rule out underlying pneumonia
• Assessment of the percentage of body surface area (TBSA) involved is important in classifying SJS/TEN.

  Approximately one hand (palm and fingers) of the patient is equivalent of 1% TBSA.
• SCORTEN scoring system:

  • Prediction of mortality in patients with SJS/TEN
  • Should be calculated within the first 25 hours of hospitalisation and continued for the first 5 days
  • Prognostic factors (1 point each) = age >40, HR >120, malignancy, TSBA >10%, urea >10, bicarb <20, glucose >14
• SJS/TEN is similar to second-degree burns in terms of physical effects, and are therefore treated in the same way.This entails optimal daily wound care, oral care and nutrition, fluid balance, pain management and eye care.
• Immediate care:

  • Withdraw causative agent immediately
  • ABCDE approach
  • Determine whether the patient is in respiratory distress - ABG and oxygen sats - intubation may be needed
  • Establish peripheral venous access
  • Immediate assessment of TBSA
  • Calculate SCORTEN within first 24 hours
• Management:

  • If TSBA >10% or SCORTEN >3 - burn centre or ICU
  • Skin care - examine daily for extent of detachment and infection, dressings and emollients
  • Eye care - assessment by ophthalmologist, eye drops/ointments
  • Monitor fluid balance
  • Oral hygiene and nutritional support - require high caloric supplements
  • Analgesia - do not use NSAIDs (can cause SJS/TEN)
• General care:

  • Prophylactic anticoagulation
  • Regular assessment for signs of infection - prophylactic antibiotics not recommended
  • Psychiatric support
  • Physiotherapy and occupational therapy
• Specialist therapies sometimes used:

  • Ciclosporin
  • IVIG
  • systemic steroids - cortisone
  • Anti-TNFa monoclonal antibodies e.g. infliximab
• atients should avoid sunlight exposure and sunburn for at least 1 year to promote healing of skin, especially the areas that were affected by the rash, blisters and sloughing. They should use an emollient to aid skin healing.

  Because they may have a genetic predisposition, these patients should never self-medicate with antibiotics or over the counter drugs without a doctor’s approval
• The acute phase of SJS/TEN typically lasts between 8-12 days.

  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.
• Acute complications:

  • Dehydration
  • Infection
  • Hypothermia
  • Ocular - tear duct loss, ulcerations, anterior uveitis
  • Acute liver injury
  • Acute renal failure
  • GI - ulceration, perforation and intussusception
  • Coagulopathy - thromboembolism and DIC
  • Shock and multi-organ failure
• Chronic complications:

  • Abnormal skin complications
  • Scarring
  • Nail plate loss
  • Acute compartment syndrome
  • Vaginal synechiae - fusion
  • Pulmonary - bronchitis, bronchiectasis