Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are forms of a life-threatening skin disease that also includes a less serious condition known as bullous erythema multiforme (EM). Because these “vesiculobullous” diseases are rare, determining their rate of incidence with any degree of accuracy has proven challenging.
In about half the cases, the cause is not known. In most of the other half of the cases, the use of drugs has been identified as the culprit, and specific drugs have been implicated. Unfortunately, since the conditions’ link to these drugs is based mostly on case reports, there are no satisfactory risk estimates. Some cases are caused by a bacterial infections, antibiotics, carcinomas, and lymphomas.
SJS and TEN can occur in anyone with no gender or racial predilections. It is more common among older people and those with AIDS, but probably because these groups tend to use more drugs. Those with EM tend to skew slightly younger.
Both TEN and SJS begin with one to several days of fever, coughing, a sore throat and malaise. In 90 percent of TEN and all of SJS cases, mucosal membranes are then affected, usually the oropharynx, followed by the eyes and genitalia. Other mucosal surfaces that may be affected include the intestinal tract, the esophagus, and the respiratory epithelium. Blister, skin lesions and bleeding in these areas may make it painful to eat, drink or urinate.
There is some disagreement over whether EM, SJS and TEN are separate disorders or different severities of the same condition, in part because they are distinguished primarily by severity and percentage of body surface involved. The following classifications, however, are generally agreed upon:
- Bullous EM – presents with localized target lesions, sometimes raised atypical targets. There is epidermal detachment, or sloughing of skin, in less than 10 percent of the body’s surface area.
- SJS, or EM major – begins with malaise and fever and is followed by the rapid onset of purpuric macules or erythematous and plaques. There is epidermal detachment on less than 10 percent of the body’s surface area.
- Overlap SJS-TEN – also characterized by widespread purpuric macules or erythematous or flat atypical targets, but with epidermal detachment between 10-30 percent of the body’s surface area.
- TEN “with spots” – characterized by widespread purpuric macules or flat atypical targets and sloughing of skin in over 30 percent of the body’s surface area.
- TEN “without spots” – skin sloughs off in large epidermal sheets from over 30 percent of the body’s surface area. No targetlike lesions or purpuric macules present.
The drugs identified as likeliest to be responsible for causing TEN and SJS include:
- Sulfonamide antibiotics
- Anticonvulsants such as phenytoin (DILANTIN), phenobarbital, carbamazepine (TEGRETOL) and valproic acid
- Some nonsteroidal anti-inflammatory drugs (NSAIDs)
- COX-2 inhibitors such as rofecoxib (VIOXX, celecoxib (CELEBREX), valdecoxib (BEXTRA), which was pulled from the market in 2005
- Allopurinol (LOPURIN, ZYLOPRIM)
- Antiretroviral medications
- Corticosteroids
The introduction of infectious agents such as bone marrow and other organ transplants, immunizations, and Mycoplasma pneumoniae have also been identified as potential causes.
Those who suffer from TEN or SJS are hospitalized and any drugs suspected of causing the condition are discontinued. They are often treated in a burn unit where they can get specialized attention to avoid infections, which are usually viral and may include herpes simplex, influenza, mumps, cat-scratch fever, histoplasmosis, and Epstein-Barr. If infection develops, antibiotics are given immediately.
Unlike as in the case with burns, however, those who survive grow back their own skin, so skin grafts are not required. Fluids and salts lost through the damaged skin are replaced intravenously. Some doctors administer large doses of corticosteroids within the first few days, but this practice is controversial because these drugs suppress the immune system. To prevent further progression of blistering and immune damage to the skin, many of those suffering from TEN are given intravenous human immunoglobulin (IVIg).
The mortality for those with SJS is five percent. A SCORTEN scale can be used to estimate that of more severe cases, but the general prognosis of TEN is poor. The mortality rate for TEN is as high as 40 percent. Other potential outcomes include organ failure and blindness.