Clinical presentation

Patients may present with a prodrome of fever, stinging eyes, painful swallowing, followed by the development of dusky erythematous macules that progress to flaccid blisters. Two or more mucous membranes are usually involved, with erythema and erosions of the buccal, genital and ocular mucosa. Severe ophthalmic involvement may lead to permanent scarring and blindness. Epidermal detachment is common, which may lead to massive fluid loss and electrolyte imbalance.

Although several classification systems for Stevens-Johnson syndrome and TEN exist, the most widely accepted divides the spectrum into five categories (Table 5).[176]

Table 5.    Clinical classification of cases of toxic epidermal necrolysis, Stevens-Johnson syndrome and erythema multiforme

1. Bullous erythema multiforme:  epidermal detachment involving < 10% of the body surface, couple with localised typical target or raised atypical targets

2. Stevens-Johnson  syndrome  (SJS):  epidermal  detachment  of  < 10%  of  the  body  surface  in  association  with  widespread erythematous or purpuric macules or flat atypical targets, haemorrhagic erosions of the lips

3. SJS  and  toxic  epidermal  necrolysis  (TEN)  overlap:  epidermal  detachment  of  10-30%  of  the  body  surface  plus  widespread purpuric macules or flat atypical targets

4. TEN with spots: epidermal detachment of > 30% of the body surface coupled with widespread purpuric macules or flat atypical targets

5. TEN without spots: large sheets of epidermal detachment involving > 10% of the body surface without purpuric macules or target lesions