| Summary points: | A 3-year-old girl presents with a papular skin eruption on the finger nail margins of both hands, her scalp, and around the nares, associated with significant arthralgia affecting her wrists and knees. Physical examination, x-ray, computed tomography, and histopathology are described; images provided. The authors discuss the different diagnoses to consider in children with xanthomas and arthritis, as well pharmacologic therapies used in children with multicentric reticulohistiocytosis. |