[Table/Fig-9]:

Clinical variants of EM

Infections	Drugs
EM minor	Typical target lesions, raised atypical target lesions, minimal mucous membrane involvement and, when present, at only 1 site (most commonly the mouth). Oral lesions; mild to severe erythema, erosions and ulcers. Occasionally may affect only the oral mucosa. < 10% of the body surface area is affected.
EM major	Cutaneous lesions and at least 2 mucosal sites (typically oral mucosa) affected. < 10% of the body surface area involved. Symmetrically distributed typical target lesions or atypical, raised target lesions or both. Oral lesions usually widespread and severe.
Stevens-Johnson syndrome	Main difference from EM major is based on the typology and location of lesions and the presence of systemic symptoms. < 10% of the body surface area is involved. Primarily atypical flat target lesions and macules rather than classic target lesions. Generally widespread rather than involving only the acral areas. Multiple mucosal sites involved, with scarring of the mucosal lesions. Prodromal flu-like systemic symptoms also common.
Overlapping Stevens-Johnson syndrome and toxic epidermal necrolysis	No typical targets; flat atypical targets are present. Up to 10%–30% of the body surface area affected. Prodromal flu-like systemic symptoms common.
Toxic epidermal necrolysis	When spots are present, characterized by epidermal detachment of > 30% of the body surface and widespread purpuric macules or flat atypical targets. In the absence of spots, characterized by epidermal detachment > 10% of the body surface, large epidermal sheets and no macules or target lesions.
Drug related erythema multiforme	Typically affect the oral mucosa, the lips and bulbar conjunctivae. Initially bullae rupture to give rise to haemorrhagic pseudo membrane of the lips and wide spread superficial oral ulcarations.
Drug related Toxic epidermal necronecrolysis	Toxic epidermal necrolysis (Lyell syndrome) is clinically characterised by extensive mucocutaneous epidermolysis preceded by a macular or maculopapular exanthema and enanthema (Lyell, 1979; Rasmussen et al, 1989). Intraorally there is widespread painful blistering and ulceration of all mucosal mucosal surfaces. Toxic epidermolysis may be associated with antimicrobials (sulphonamides and thiacetazone), analgesics (phenazones). antiepileptics, allopurinol, chlormezanone, rifampicin, fluconazole and vancomycin.