Stevens-Johnson syndrome and toxic epidermal
necrolysis (SJS-TEN): begins as fever + a painful
diffuse symmetrical rash (erythema, dusky patches,
coalescing erythematous ± purpuric macules),
starting in the face and thorax, before spreading
elsewhere but sparing scalp, palms and soles. Later,
bullae form and skin sloughs to give large erosions;
the body surface area desloughed distinguishes SJS
(<10%), SJS-TEN overlap (10-30%), and TEN
(>30%). Mucous membranes are almost always
involved – painful mucositis, ulcers, conjunctivitis,
urethritis. Patients are systemically ill with fever,
anaemia, ↓ TW, fluid loss with electrolyte
imbanaces, and 2° bacterial infection. Etiologies of
SJS/TEN are drugs (see below) and infection (e.g.
mycoplasma).