A linear band of erythematous, flat-topped papules on the forearm

An 8-year-old girl presented with an asymptomatic rash on the left forearm with an abrupt onset that had been present for several months and had never been treated. There was no history of trauma to the involved area. She had atopic dermatitis but was otherwise in excellent health. Her immunizations were all up to date and she did not have any adverse reactions to the vaccinations