Diagnostic Significance of Cerebrospinal Fluid Flow Cytometry in Chinese Children with B Lineage Acute Lymphoblastic Leukemia

Background: Central nervous system leukemia (CNSL) is among the most important causes of the poor prognosis of childhood leukemia. We aimed to compare the sensitivity of cytomorphology (CM) and flow cytometry (FCM) in diagnosing CNSL, emphasizing the importance of FCM in the diagnosis process. Methods: : One-hundred-sixty-five children with newly diagnosed B-cell Acute Lymphoblastic Leukemia (B-cell ALL) were included in this study. Cerebrospinal fluid (CSF) samples were taken for routine CSF analysis, CM analysis, and FCM examination. Computed tomography scans and/or magnetic resonance imaging were performed at diagnosis. Patients with CNS2, CNS3, and traumatic lumbar puncture (TLP) at diagnosis received two additional courses of triple intrathecal injections during induction treatment. We compared the sensitivity of FCM and CM in the diagnosis of children with CNSL. Results: : One hundred and twenty-eight (77.58%) CSF samples were negative by either CM or FCM (CM - /FCM - ), four (2.42 %) were positive by both CM and FCM (CM + /FCM + ), and thirty-three (20%) displayed a single positive finding by FCM (CM - /FCM + ) (p=0.044). By adding two lumbar injections in the induction treatment, ten children with TLP + had no CNS relapse, like those with TLP - . However, compared to CNS1 and TLP, the event-free survival (EFS) did not significantly improve in patients with CNS2 and CNS3. Moreover, CNSL status was associated with worse 3-year EFS (p<0.05). Conclusions: : We demonstrated the FCM significance in the diagnosis of CNSL in children. To improve the EFS rate of childhood leukemia, it is necessary to combine CM examination, FCM, and other biomarkers for the early diagnosis of CNSL.