Toxic Epidermal Necrolysis

Toxic epidermal necrolysis (TEN) is a rare but potentially life-threatening skin disease that causes the top layer of the skin, the epidermis, to slough off. The incidence of TEN is 0.4 to 1.2 cases per million each year but the risk is higher for people who have HIV/AIDS. The majority of cases are caused by drugs.

What Causes Toxic Epidermal Necrolysis?

The immune system attacks large areas of the epidermis and causes the cells that hold the skin together to suddenly die. There are over 100 drugs that have been associated with TEN, but the most common drugs are:

• Sulfa antibiotics like Septra (trimethoprim-sulfamethoxazole)
• Some non-steroidal anti-inflammatory drugs (NSAIDs) like piroxicam
• Allopurinol
• Anti-seizure medicines like carbamazepine, lamotrigine, phenobarbital, and phenytoin.
• Corticosteroids like prednisone
• Antiretroviral drugs for HIV/AIDS

Symptoms of Toxic Epidermal Necrolysis

The first symptoms of TEN are similar to influenza symptoms: fever, cough, aching muscles and joints and fatigue. These symptoms can last from 1 day to 2 weeks before the rash starts. The rash of TEN starts as a reddish-gray discoloration of the skin that begins on the trunk or face. As the epidermis separates from the dermis, fluid builds up between the two layers creating a large blister and any sideways pressure on the skin causes the epidermis to tear away in sheets.

This same process goes on in the mucous membranes of the mouth, eyes, and genital area. Blisters in the mouth are painful and make it difficult to eat. The eyes can become red, swollen, crusted, and sensitive to light. Urination and defecation can be very painful along with pain and bleeding inside the vagina.

The skin starts regenerating the epidermis within 3 days but it can take up to 3 weeks to complete the process.

Diagnosis of Toxic Epidermal Necrolysis

The diagnosis of TEN is usually made clinically, meaning based on the typical appearance of the rash. Often a skin biopsy is done to confirm the diagnosis. Next, doctors estimate the amount of the body surface area (BSA) involved just like in burns. A less extensive form of TEN is Stevens-Johnson syndrome (SJS) which involves less than 10% of BSA. Involvement of between 10% to 30% of BSA is called SJS-TEN overlap. Finally TEN involves greater than 30% of BSA.

Treatment of Toxic Epidermal Necrolysis

Identifying and stopping the drug causing this reaction as quickly as possible reduces the severity of the disease. Most people with TEN are treated in burn centers because they require extensive care similar to burn victims.

Prognosis of Toxic Epidermal Necrolysis

Approximately 30% to 50% of people with TEN die, usually from overwhelming bacterial or fungal infections, kidney failure, or severe pneumonia. People who survive may have scarring, uneven pigmentation or persistent eye problems.

_Sources:

_{Borchers, AT et al. "Stevens-Johnson syndrome and toxic epidermal necrolysis." Autoimmun Rev. 7(2008): 598-605.}

_{French, Lars, and Christa Prins. "Erythema Multiforme, Stevens-Johnson Syndrome, and Toxic Epidermal Necrolysis." Dermatology, 2nd Ed. Eds. Jean Bolognia, and et. al. Mosby, 2008: 291-9}

_{Pereira, FA et al. "Toxic epidermal necrolysis." J Am Acad Dermatol. 56(2007): 181-200.}