Juvenile xanthogranuloma developing after treatment of Langerhans cell histiocytosis: case report and literature review.

The synchronous or metachronous development of Langerhans cell histiocytosis and non-Langerhans cell histiocytosis in the same patient is rare. To date, only seven cases of xanthogranulomas developing in young patients with a history of Langerhans cell histiocytosis and systemic therapy have been reported in the literature. As of yet, the pathogenesis and the clinical significance of this phenomenon are unclear. We report the case of a 3 year old boy who developed juvenile Xanthogranulomas on the forehead and right upper eye lid 1.5 years after systemic therapy for monosystemic Langerhans cell histiocytosis of the bone and complete disease remission.