Why is EM major now considered to be distinct from SJS/TEN?
EM major can usually be distinguished from SJS/TEN on a number of clinical criteria:. • Type of skin lesion – the predominant skin lesion of EM is the typical and atypical target papules and plaques and not macules which develop into sheets of skin detachment as seen in SJS/TEN. Skin detachment of more than 1% of the body surface area is common in SJS/TEN but uncommon in EM. • Distribution of the skin lesions – in EM the lesions are predominantly acrally distributed, i.e., begin on hands and feet. In SJS/TEN the eruption begins on the trunk. • Mucosal involvement – although in EM major more than two mucous membranes can be affected, this is less common in EM and is milder (lesser severity and extent) compared to SJS/TEN. • Systemic symptoms, e.g. fever, are absent or mild in EM but are prominent in SJS/TEN, especially in the prodromal period. Fever, when present in EM, is mild (<38.5C) compared to high fevers with SJS/TEN. Patients with SJS/TEN are systemically ill. • Outcome and progn
