Efficacy and Safety of Low-Dose Cytarabine Combined With Thalidomide in Adult Patients With Untreated LCH

Inclusion Criteria: * Clearly diagnose and treat adult patients with multisystem or single-system multifocal LCH; * Aged between 18 and 70 years; * Multisystem involvement or single-system multifocal disease; * No prior systemic treatment (patients who have only received local radiotherapy or surgery may be enrolled); * ECOG performance status score ≤ 2; * Judged by clinicians as suitable for treatment with this protocol; * Patients or their families able to understand the study protocol and willing to participate in the study, providing written informed consent. Exclusion Criteria: * Patients with LCH involving the central nervous system; * Single-system single-lesion LCH; * Subjects who have undergone major surgery within 4 weeks prior to the first dose in the study; * Subjects who have received radiotherapy within 4 weeks prior to the first dose in the study; subjects with a history of myocardial infarction within the past year; * Patients with New York Heart Association (NYHA) class 3 or 4 congestive heart failure, or a history of NYHA class 3 or 4 congestive heart failure; * Pregnant or lactating women; * Abnormal liver and kidney function: creatinine level ≥176.8μmol/l (2mg/dl), transaminase and bilirubin levels more than 2 times the upper limit of normal (for LCH patients with liver involvement, bilirubin levels more than 10 times the upper limit of normal); * Abnormal blood counts: absolute neutrophil count less than 1×10\^9/L, platelet count less than 50×10\^9/L; * Patients or their families unable to understand the conditions and objectives of this study; * Any other circumstances in which the investigator deems the patient unsuitable to participate in this trial.