Purpose: To explore the diagnostic value and the prognostic significance of cerebrospinal fluid (CSF) examination by flow cytometry (FC) in children with central nervous system leukemia (CNSL). Method: This is a retrospective observational study. We select 986 pediatric patients with newly diagnosed acute lymphoblastic leukemia from January 2012 to December 2018 as the research objects and analyze the sensitivity and specificity of different methods for diagnosing CNSL. The recurrence rate and survival rate of CNSL in different groups were compared. Results: Among the 986 cases, 31 cases (positive rate of 3.14%) were positive by FC, and the cytospin-based cytomorphology (CC) test was positive in 6 cases (positive rate of 0.61%). CC combined with FC might improve the diagnostic sensitivity (from 30% to 65%, 𝑥2 value was 5.143, P = .016). The 2-year event-free survival (EFS) of 31 FC + children was 59.5% ± 9.2%, and that of 955 FC - children was 74.1% ± 1.8% (P = .004). The 2-year overall survival (OS) of the 2 groups were 63.6% ± 9.7% and 80.2% ± 1.5%, respectively (P = .004). In order to exclude the influence of CNSL, we divided the patients into 3 groups: CNSL group and non-CNSL group with CSF FC + , FC - group. There was no significant difference in EFS between FC - group and non-CNSL group with FC + (2-year EFS were 74.1% ± 1.8% and 68.7% ± 9.8%, respectively, P = .142), and there was a significant difference in OS (2-year OS were 80.2% ± 1.5% and 67.5% ± 10.3%, respectively, P = .029). Conclusion: The test of FC combined with CC may improve the diagnostic sensitivity of CNSL. The EFS and OS of children with FC + are worse than those of children with FC -. However, for those patients with non-CNSL, but only FC + at the initial diagnosis, the EFS is not significantly affected by strengthening systemic chemotherapy and increasing the number of intrathecal injections.
Keywords: acute lymphoblastic leukemia; central nervous system leukemia; cerebrospinal fluid; children; flow cytometry.