Hematopoietic stem cell transplantation in patients with severe Langerhans cell histiocytosis and hematological dysfunction: experience of the French Langerhans Cell Study Group.

The aim of this study was to assess the results of hematopoietic stem cell transplantation (HSCT) in refractory Langerhans cell histiocytosis (LCH). Among 85 patients with LCH and hematological dysfunction diagnosed in France between 1987 and 2000, eight received HSCT in six institutions. Median age at diagnosis was 0.54 years. The median LCH activity score at diagnosis was 10 (range 3-20). All patients responded poorly to initial chemotherapy. At the time of HSCT, the median activity score was 16.5 (range 7-18). HSCT was autologous in three cases and allogeneic in five cases. The conditioning regimen consisted of TBI in two cases and chemotherapy alone in six cases. Conditioning had to be attenuated in two patients. All patients had persistent active disease after autologous HSCT, which was fatal in two cases and controlled by chemotherapy in one case. After allogeneic HSCT, two patients died from toxicity and three had complete responses; two patients had had no recurrences after 21 months and 7 years of follow-up, while the other patient relapsed and died from sepsis related to splenectomy. HSCT for refractory LCH can thus be highly toxic but can also achieve sustained disease control.