Approach

Characteristic clinical presentation and skin biopsy results are sufficient to diagnose SJS/TEN. Consider transfer to a burn unit in more severe cases.

History

A thorough history is essential, focusing on recent drug or medication use, bacterial or viral infection, and vaccinations. Common historic factors associated with SJS and TEN include comorbidities such as seizures, systemic lupus erythematosus, HIV-positivity, collagen vascular disease, active cancer, and certain treatments including radiation therapy and bone marrow transplantation.[50][51][52]

The most frequently implicated drugs for SJS/TEN are listed in the etiology section. See Etiology.

The most common anticonvulsants precipitating SJS and TEN are carbamazepine, phenobarbital, phenytoin, lamotrigine, and valproic acid.[25][26] SJS and TEN usually develop in individuals who have started taking the medication for 1-14 days as a new drug; if drugs are used for months or years, the risk for developing SJS and TEN usually occurs in the first 2 months of treatment.[24][26] The index day for developing SJS and TEN is less than 1 month after starting medication (15 days for carbamazepine, 24 days for phenytoin, 17 days for phenobarbital).[24]

Assessment of disease severity

Pulmonary status

Patients with SJS/TEN should be assessed in the same way as a patient with cutaneous burns, using a structured approach to evaluate airway, breathing, and circulation. See Cutaneous burns (Diagnosis approach).

One potential complication of SJS/TEN is mucosal involvement of the upper and lower respiratory tract, with vesicle formation, ulceration, and mucosal sloughing that may lead to laryngeal stridor, along with possible retractions and edema of the nasopharynx. If there is respiratory distress or edema of the oropharyngeal tissues, intubation may be necessary to maintain the airway.[54] 

Arterial blood gases and oxygen saturation will help determine the patient's clinical respiratory status.

Total body surface area (TBSA)

Determination of the TBSA percent affected by SJS/TEN is important for severity assessment. Various methods have been used.

Wallace's rule of 9s SJS/TEN

[Figure caption and citation for the preceding image starts]: Rule of ninesFrom Dr Sheridan's personal collection [Citation ends].com.bmj.content.model.Caption@4a201b42

This provides a quick approximation of the area of skin burnt.[55] Arbitrarily, it divides the body into units of surface area divisible by 9, with the exception of the perineum. Usually, charts of area are available in most burn units. Wallace rule of 9s Opens in new window

In an adult, the following are the respective percentages of the TBSA:

  • Head and neck total for front and back: 9%

  • Each upper limb total for front and back: 9%

  • Thorax and abdomen front: 18%

  • Thorax and abdomen back: 18%

  • Perineum: 1%

  • Each lower limb total for front and back: 18%.

The rule of 9s is relatively accurate for adults but not for children, because of the relative disproportion of body-part surface area.

Palmar surface

The surface area of a patient's palm (including fingers) is roughly 0.8% of TBSA. Palmar surface can be used to estimate relatively small burns (<15% of total surface area) or very large burns (>85%, when unburnt skin is counted). For medium-sized burns, it is inaccurate.[56] 

Lund-Browder burn estimate chart

[Figure caption and citation for the preceding image starts]: Lund-Browder diagramFrom Dr Sheridan's personal collection [Citation ends].com.bmj.content.model.Caption@76ee2ce8This chart compensates for the variation in body shape with age, and therefore can give an accurate assessment of burns area in children.[55][57] 

SCORTEN

Starting within the first 24 hours of hospitalization, and continued for the first 5 days of admission, this severity of illness score is supposed to predict the risk of mortality for patients who develop SJS/TEN. The patient gets 1 point for each of the following:[58][59]

  • Age >40 years

  • Malignancy

  • >120 bpm tachycardia

  • Initial % TBSA >10%

  • Serum BUN >10 mmol/L

  • Serum glucose >14 mmol/L

  • HCO3 <20 mmol/L.

Although the group originating the SCORTEN score, and some others, have found the scoring system useful, others have not.[60][61][62]

More than likely, the more frequent recent use of intravenous immune globulin in these patients has impacted some of the validity of this scoring system for TEN.

Physical exam

When patients present in the early course of disease, signs and symptoms may appear relatively mild. However, the condition typically progresses over several days, so close monitoring and regular reassessment is essential.

Initial symptoms include a sudden rash or a rash that develops after a new medication is started. There is a wide variation of lesion type and skin involvement. Common sites of skin involvement are:[63]

  • Upper torso

  • Proximal limbs

  • Face

Lesions spread from these sites to involve the rest of the trunk and distal limbs; involvement of the palms of the hands and soles of the feet is often prominent.[20][63]

Blisters or macules and flat atypical target lesions, diffuse erythema, and Nikolsky sign (epidermal layer easily sloughs off when pressure is applied to the affected area) may be noted.[20][63] Mucosal involvement presents with erosions or ulceration of the eyes, lips, mouth, pharynx, esophagus, gastrointestinal tract, kidneys, liver, anus, genital area, or urethra.[63]

Other potential presenting features include:

  • Fever

  • Swelling of the tongue

  • Diarrhea

  • Vomiting

  • Dysuria

  • Enlarged lymph nodes

  • Arthralgias

  • Arthritis

  • Bronchitis

  • Shortness of breath

  • Wheezing

  • Hypotension

  • Dehydration.

Laboratory tests and imaging

Laboratory tests include:[63]

  • Complete blood count

  • Metabolic panel (glucose, electrolytes [phosphate/magnesium], blood urea nitrogen, creatinine, calcium, bicarbonate)

  • Liver function tests (alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, total protein, albumin)

  • C-reactive protein (CRP)

  • Coagulation studies

  • Arterial blood gas and saturation of oxygen - to assess for respiratory compromise

  • Blood culture - to rule out toxic shock syndrome and scalded skin syndrome, which would show positive culture for Staphylococcus or Streptococcus species

  • Skin swab from lesional skin

  • Mycoplasma serology

  • Skin biopsy - definitive test for SJS, SJS/TEN overlap, and TEN (assessed in conjunction with clinical presentation).[19] A dermatologist should take a biopsy at the transition point of blistering, to assess the level of skin desquamation. The separation will occur at the epidermal-papillary dermal junction, with the presence of necrotic cells and lymphocytes.

  • Direct immunofluorescence - may be performed on the perilesional biopsy to exclude autoimmune blistering disease.[2][63]

Do not order erythrocyte sedimentation rate (ESR) to detect acute phase inflammation. Order CRP instead as it is more sensitive and specific than ESR for detecting the acute phase of inflammation in patients with SJS/TEN. In the first 24 hours of a disease process, CRP will be elevated, whereas ESR may be normal. If the source of inflammation is removed, CRP will return to normal within a day or so, whereas ESR will remain elevated for several days until excess fibrinogen is removed from the serum.[64]

Imaging tests

Due to the high risk of pneumonia and interstitial pneumonitis all patients should have a chest x-ray.[63]

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