Erythema multiforme (EM) is a hypersensitivity skin condition involving T-cell and B-cell responses for which the main causes are infectious factors (eg, herpes simplex virus, Mycoplasma pneumoniae). Antiplakin autoantibodies are found in some patients. EM has a chronic course (ie, recurrent or subintrant) in 40% of cases. Mucous membrane involvement causes relevant morbidity and impairs quality of life.1