Treatment of persistent erythema multiforme with upadacitinib: A novel therapeutic approach.

Erythema multiforme (EM) is an inflammatory skin disease characterized by targetoid lesions, which may also affect the mucous membranes. Most cases are self-limited; however, some individuals develop recurrent disease with annual flares, frequently when associated with herpes simplex virus infection. A third rare subgroup of disease, persistent EM (PEM), is characterized by the continuous appearance of typical or atypical lesions, which may persist for years.1,2 Classic and recurrent EM is commonly precipitated by infectious agents including herpes simplex virus, Epstein-Barr virus, and Mycoplasma pneumoniae.