Mixed diagnoses – 10 cases (3 of 11)

The patient presents with Steven's Johnson syndrome, or erythema multiforme (EM) major. It is predominantly a mucosal eruption of erosions and blisters in the oropharynx, on the lips, conjunctivae and genitalia accompanied by fever and prostration. However there are generally a few target lesions on the distal limbs, hands and feet and these are sometimes bullous.

EM major is usually a drug eruption especially to sulphonamides, anticonvulsants, allopurinol and antibiotics prescribed within the previous three weeks (rarely, up to eight weeks). It is more common in patients with immunodeficiency especially due to HIV. EM major to sulphonamides may be familial in those with slow-acetylator status.

Contrast this with EM minor, which is usually a reaction to viral infection, especially herpes simplex and orf. However, mycoplasma infection may provoke EM with mucosal lesions, especially in children.

The responsible drug should be stopped and the patient should be admitted to hospital for observation and supportive care. This will include fluid replacement, wound and mouth care. Oral corticosteroids are probably best avoided.

Spontaneous recovery usually occurs within one to three weeks but the occasional case is fatal. Permanent mucosal scarring is possible.

Early toxic epidermal necrolysis (TEN) presents in the same way as EM major but is soon followed by widespread blistering and erosions. TEN is more serious and requires multidisciplinary management in an intensive care unit.