Excellent remission rates with limited toxicity in relapsed/refractory Langerhans cell histiocytosis with pulse dexamethasone and lenalidomide in children.

Refractory/relapsed Langerhans cell histiocytosis (LCH) has a difficult course with a guarded prognosis. We used a novel protocol including six cycles of pulse dexamethasone and lenalidomide in four children with LCH refractory to first-line agents and courses of cladribine and cytarabine or single-agent cladribine. All four children completed the protocol without any significant adverse effects and remain in complete and durable remission 15-18 months posttreatment. The novel protocol we propose for relapsed/refractory LCH is cost-effective and outpatient-based with durable remission and minimal toxicity. This is particularly suited for resource-limited settings.