TEN vs. SJS vs. EM

Stevens Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe skin hypersensitivity reactions. Most common precipitating causes are drugs, especially sulfonamides, antiepileptics, and antibiotics. Erythema multiforme (EM) is a milder condition that is considered to be on the same spectrum as SJS and TEN. Quiz 22 has a picture of a patient with EM. You can read more about EM here.

SJS and TEN are clinically similar but differ in their distribution. The most commonly accepted definition of SJS is that changes affect < 10% of body surface area. When > 30% of body surface area is affected the patient is called to have TEN; involvement in between 10 to 30% of body surface area is considered SJS-TEN overlap conditions.

Relatively common causes of SJS/TEN other than medications include:

-Infection (mostly with Mycoplasma pneumoniae)
-Vaccination
-Graft-vs-host disease

Symptoms generally appear within a few weeks of the strarting the offending medications. Systemic symtoms such as weakness, sore throat and red eyes are common in the beginning. Rash is initially macular, often in a target configuration, progressively becoming vesiculo-bullous and sloughing over a period of 3-4 days. Nikolsky's sign is positive (epidermal skin slides off on pressure). Mucosa is involved and at times even the bronchial epithelium can shed leading to respiratory distress.

Treatment of TEN is similar to extensive burns. Immune modulator treatment (IVIG, steroids, cyclophosphamide) and plasmapheresis have been tried and prophylactic antibiotics are controversial.