Derm Dx: Clusters of smooth, pearly umbilicated papules in a 4-year old

An otherwise healthy 4-year-old girl presents with clusters of smooth, pearly, umbilicated papules 2-to-6 mm in diameter. The rash first appeared as groups of waxy, skin-colored papules on the girl’s arm, but soon spread to her torso, axilla, face and eyes and became inflamed and itchy.

The girl is enrolled in swimming lessons at the local public pool and family history ...