Coexistence of cutaneous Langerhans cell histiocytosis and reticulohistiocytosis with initial presentation of skull lesions

Coexistence of Langerhans cell histiocytosis (LCH) and reticulohistiocytosis (RH) in different organ and the same skin area is never reported in the literature. We present a 20-year-old female adult with coexistence of bone LCH and diffuse cutaneous RH initially, and then progressed to multisystem LCH with synchronous development of LCH and RH in the skin after chemotherapy for one year. In our patient, multifocal bone LCH and diffuse cutaneous RH coexisted before chemotherapy. After she completed cytarabine (Ara-C) for 12 times, bone LCH much improved but cutaneous LCH developed on previous RH lesions.