Dermatological Emergencies: Toxic Epidermal Necrolysis (T.E.N.)

Toxic epidermal necrolysis (T.E.N.) has distinct clinical features, such as erythema that affects more than 30% of the skin's surface, supported by mucosal involvement and fever (greater than 38 degrees Celsius). Erythema is followed by extensive full-thickness mucosal and cutaneous necrosis (death of cells or tissues) and denudation that lasts 2 to 3 days. The similar symptoms and signs that involve less than 10% of the body surface are referred to as Stevens-Johnson syndrome (SJS). If 10 to 30% of the body surface area is affected by the symptoms mentioned above, it is referred to as T.E.N./SJS overlap.

The prodromal rash can be non-specific or can target certain lesions. It is followed by the appearance of blisters filled with fluid that tend to spread with lateral pressure (Nikolsky's sign) and eventually peel off, revealing bright red oozing dermis. Shedding of hair and nails can occur as well.

The mechanism of T.E.N. is related to a cell-mediated cytotoxic reaction caused against epidermal cells and activated by lymphocytes and their cytokines.

T.E.N. is a serious medical emergency with a high mortality rate. It should be treated in an intensive care facility or burn unit. By nature, it is a rare condition with an incidence of approximately one per million per year.

Acute graft versus host disease can also trigger the occurrence of T.E.N., and the effects are usually lethal.

Common Causes

The most common drugs that can cause T.E.N. include nonsteroidal anti-inflammatories, sulphonamides, allopurinol, and anticonvulsants such as lamotrigine, carbamazepine, and phenytoin.

Investigations

Further investigations of T.E.N. are performed to study various complications associated with the disease and to explore underlying causes. Skin swabs are conducted to detect the presence of secondary bacterial infection. Other forms of investigation include a full haematological and biochemical screen.

Complications

T.E.N. is associated with numerous health complications, including protein loss, difficulties with thermoregulation, dehydration, interstitial pneumonitis, neutropaenia, liver failure, heart failure, renal tubular necrosis, and erosion of the gastrointestinal tract.

Severity Scoring: SCORTEN

SCORTEN is a specially designed illness severity score that assists physicians in predicting mortality rates associated with T.E.N. and SJS cases. The criteria include the following factors: age greater than 40 years, presence of malignancy, heart rate above 120, initial epidermal detachment greater than 10%, serum glucose level greater than 14 mmol/L, serum urea level greater than 10 mmol/L, and serum bicarbonate level less than 20 mmol/L. Each criterion equals one point.

• SCORTEN 0 to 1: predicted mortality greater than 3.2%
• SCORTEN 2: predicted mortality greater than 12.1%
• SCORTEN 3: predicted mortality greater than 35.3%
• SCORTEN 4: predicted mortality greater than 58.3%
• SCORTEN 5 to 7: predicted mortality greater than 90%

Management

In the presence of T.E.N., it is strongly advised that any recently prescribed medications be discontinued. Such medications should never be re-administered in the future, as recurrent T.E.N. is considerably more severe than the initial episode.

Management of T.E.N. is typically carried out in an intensive care unit where expert supportive care is available. The environment should be kept warm, fluids should be regularly replaced, and any electrolyte disturbances should be corrected immediately. Prevention of sepsis is achieved through the administration of intravenous antibiotics. Additional measures include the introduction of analgesics, mucosal emollients, and non-stick occlusive burns dressings.

Systemic corticosteroids should be avoided, as they increase the mortality rate, though their usage remains a subject of ongoing clinical debate.

Recovery

The recovery process typically takes 10 days to 3 weeks. Possible long-term effects include mucosal scarring, irregular pigmentation, and ocular complications.