A Prospective Institutional Study for the Treatment of Children With Newly Diagnosed Langerhans Cell Histiocytosis Using a Cytarabine Contained Protocol

All patients with de novo pathological confirmed LCH enrolled in this study will be classified into 4 groups. Group 1: Multisystem patients (≥2 organs/systems) with involvement of one or more "Risk" organs" (hematopoietic system, liver or spleen);Group 2:Multisystem patients, but without involvement of "Risk" organs; Group 3: Single system, Multifocal+ Single system, unifocal and special site@ (Isolated lesion of special site)+ Single system, unifocal and CNS risk+Single system, unifocal i.e. thyroid, lung, thymus, hypothalamic-pituitary+Single system, unifocal and other functionally critical anatomical sites; Group 4: Single system, unifocal i.e. bone, skin or lymph node (not the draining lymph node of another LCH lesion). For patients in Group 1, a 6-week initial treatment, a 16-week consolidation continuation treatment and a 26-week maintenance continuation treatment containing cytarabine is applied. For patients in Group 2, a 6-week initial treatment containing cytarabine and a 46-week continuation treatment (without cytarabine) is applied. For patients in Group 3,a 6-week initial treatment and a 46-week continuation treatment (without cytarabine) is applied. For patients in Group 4, only local therapy followed by wait-and-see strategy is applied.