UNILATERAL LATEROTHORACIC EXANTHEM

Background: Four years ago, we began seeing young children with an unu sual, predominantly unilateral, morbilliform and eczematous, self-limi ted cutaneous eruption. It appeared to correspond to unilateral latero thoracic exanthem (ULE) reported from France and to an eruption descri bed as ''a new papular erythema of childhood'' in the United States. O bjective: We conducted a prospective study of ULE to define its clinic al evolution, pathology, and therapy. In addition, we performed epidem iologic and microbiologic investigations in an attempt to determine th e cause of ULE. Method: We studied 48 children with ULE. In some patie nts, blood, urine, stool, as well as skin biopsy specimens were analyz ed. Results: ULE is a morbilliform, eczematous eruption that often beg ins close to the axilla and spreads to become bilateral, although it u sually retains a unilateral predominance. Patients' mean age at onset is 24.3 months, with a female predominance (2:1) and mean duration of 5 weeks, followed by spontaneous resolution that may or may not be imp roved with topical corticosteroids. It is characterized by a unique ec crine lymphocytic infiltration. Although signs of infection were repor ted by most patients, no one infectious agent was identified. No signi ficant epidemiologic factor was found. Conclusion: ULE, in young child ren, is a self-limited morbilliform and scarlatiniform eruption that m ay represent a specific skin reaction to one or more infectious agents .