Background:Central nervous system (CNS) involvement is found in many patients with hemophagocytic lymphohistiocytosis (HLH).In this study,we mainly analyzed neurological symptoms,imaging findings,cerebrospinal fluid (CSF),and their relationship with outcomes of HLH children.Methods:Related data of 179 Chinese pediatric patients with HLH admitted to our center from January 2010 to December 2015 were analyzed retrospectively.Diagnosis and treatment were based on the HLH-2004 protocol.Two-tailed Chi-squared test was used to compare between different groups,and Kaplan-Meier survival curves were used to analyze the overall survival (OS) of patients with HLH.Results:In the present study,21.2％ (38/179) of total patients had neurological symptoms including seizure,irritability,somnolence,and unconsciousness.There were 80 (50.0％,excluding 19 patients without imaging data) patients with cranial imaging abnormalities.There were 14.7％ (17/1 16,excluding 63 patients who did not accept lumbar puncture) of patients with abnormal CSF results.CNS involvement is defined as abnormalities in one or more of CNS symptoms,radiological findings,and CSF.Thus,60.3％ of them had CNS involvement.As for the prognosis,the median follow-up time was 3.2 years (17 lost to follow-up).The probable 3-year OS of children was higher without CNS involvement (86.0％ ± 4.6％) than those with CNS involvement (68.9％ ± 4.9％,hazard ratio [HR] =2.286,P =0.019).Among them,the probable 3-year OS of children without CNS symptoms was 76.0％ ± 3.8％,higher than with CNS symptoms (59.5％ ± 8.1％,HR =2.147,P =0.047).The 3-year OS of children with abnormal CSF was 64.7％ ± 11.6％,compared with normal CSF (85.1％ ± 3.7％,HR =0.255,P =0.038).Conclusions:HLH patients with CNS involvement might have worse outcomes compared with those without CNS involvement,and CNS symptoms and CSF changes are more important to access the prognosis than imaging abnormality.