Erythema multiforme, stevens-johnson syndrome and toxic epidermal necrolysis

Abstract

EM is an acute, immune-mediated mucocutaneous condition, first described by von Hebra in 1866. It is characterised by the abrupt onset of red macules and papules, which evolve into characteristic target lesions. It is controversial as to whether EM is a well-defined disease or a spectrum of manifestations. EM can be divided into two forms-EM minor and EM major. Both of them are characterised by typical target lesions; however, EM minor is used to describe classic, mild disease without mucosal lesions, while EM major is characterised by systemic symptoms and mucosal involvement. The term EM major should not be used to refer to SJS. Although EM is usually selflimiting, frequent episodes over the course of years can lead to recurrent disease in some patients. The exact incidence of EM is unknown, and it occurs predominantly in young adults and has no racial predilection. Most common aetiological factors include infection, medication use, malignancy, autoimmune disease, sarcoidosis, radiation and immunisation. Of these factors, infection accounts for 90 % of cases, with herpes simplex virus as the most common identified agent. Mycoplasma pneumoniae infection is another important cause of EM, particularly in children. Genetic predisposition may play a role in some of the patients with EM; a link between EM and HLA DQB1*0301 allele has been reported. An even stronger HLA DQB1*0301 association was found in the patient group with herpes-associated EM.