LAUSR

A young child presented to clinic with a 6-month history of an asymptomatic expanding erythematous eruption on the lower legs, abdomen, and buttocks (Figure, A). The eruption would wax and wane, with each episode lasting for approximately 1 week, without residual pigmentation. Clinical examination was significant for faint, nonscaling annular serpiginous, erythematous plaques with central clearing, and barely elevated borders. Test results for erythrocyte sedimentation rate, complete blood cell count, antinuclear antibodies, anti-Ro/SSA and anti-La/SSB antibodies, and Borrelia burgdorferi antibodies were within normal limits. There was no family history of autoimmune disease, and the child had not experienced any fevers or exposures to ticks or other arthropods. A punch biopsy specimen from the left thigh was obtained, and histopathological analysis was subsequently performed (Figure, B and C).