An extended form of toxic epidermal necrolysis with characteristics of destruction and detachment of the skin epithelium and mucous membranes involving more than 30% of the body surface area. Lyell syndrome can be triggered by a drug allergy and, exceptionally, by infections or bone marrow transplantation. In 25 to 30% of cases, the cause is unclear. Patients should be admitted to an intensive care or burns unit as soon as the diagnosis is suspected. Prognosis is poor (mortality rate: 20-25%). [from
SNOMEDCT_US]