Myeloablative therapy and bone marrow transplantation for Langerhans' cell histiocytosis.

Since the Langerhans Cell (LC) is of haemopoietic origin it may be possible to cure Langerhans cell histiocytosis (LCH) by ablating the patient's own haemopoietic system and replacing it with donor bone marrow--a process termed bone marrow transplantation (BMT). This assumes that the LC itself is the fundamentally abnormal cell though BMT is also a logical therapy even if other cells of haemopoietic origin are eventually shown to be the primary cause of LCH. Marrow ablation/BMT has an appreciable morbidity and mortality and has therefore been reserved for the few LCH patients with a very poor prognosis. The results in these patients engenders cautious optimism that myeloablation/BMT in LCH may have a limited role. Myeloablative chemotherapy or radiotherapy followed by autologous bone marrow 'rescue' is also feasible but risks the return of 'untreated' LCH cells, or their precursors, causing exacerbation of disease.