CSF3 and Langerhans cell sarcoma: We report the case of a 56-year-old woman with refractory Langerhans Cell Histiocytosis (LCH) that transformed into Langerhans Cell Sarcoma (LCS) who achieved complete remission following chemotherapy with cladribine, high-dose cytarabine, G-CSF, and mitoxantrone (CLAG-M), and subsequent allogeneic hematopoietic stem cell transplantation (HSCT).