The Significance Of Flow Cytometry In The Diagnosis Of Central Nervous System Leukemia In Children

Objective:To investigate the significance of flow cytometry(FCM)in the diagnosis of central nervous system leukemia(CNSL)in children.To study the case characteristics and associated risk factors in children with CNSL.Methods:The cerebrospinal fluid(CSF)specimens of 329 children with acute lymphoblastic leukemia(ALL)who were hospitalized in the Pediatric Hematology ward of Shengjing Hospital of China Medical University from October 2018 to December 2020 were selected.The children were first-time lumbar punctures,and all of them never experienced sheath injection of chemotherapeutic drugs,and all of them had no symptoms of infection before the lumbar puncture.The peripheral blood was absent of blasts,and the laboratory results were all consistent with the conditions of lumbar puncture.1.Cerebrospinal fluid flow cytometry(FCM)and cerebrospinal fluid cytology(CC)were respectively performed to compare and analyze these two tests for the diagnosis of CNSL in children.2.The case data of the children were analyzed including:gender,age,FAB typing,peripheral blood leukocyte count,fusion gene,the presence of imaging changes on cranial computed tomography(CT),and the presence of EEG abnormalities,and the patients were also evaluated for risk typing and central nervous system(CNS)classification according to the CCLG-ALL2008 clinical typing criteria,and statistical analysis was performed to study the correlation of CNSL Influencing factors.Results:1.The FCM and CC tests were performed on the CSF specimens of 329 children with ALL,among which 67 children were detected with abnormal phenotypic cells by FCM,with a positive rate of 20.36%.6 children were detected with abnormal cells by CC,with a positive rate of 1.82%,with statistically significant differences between the two groups(P<0.001).2.Comparing the results of CSF testing in children of different sexes,among 181 male children,39 cases(21.55%)were positive for FCM and 3 cases(1.66%)for CC,with statistically significant differences(P=0.003);among 148 female children,28 cases(18.92%)were positive for FCM and 3 cases(2.03%)for CC,with statistically significant differences(P=0.009).3.Comparing the results of CSF testing in children with different types of leukemia,among 41 children with T-ALL,15 cases(36.59%)were positive for FCM and 2 cases(4.88%)were positive for CC,with no statistically significant difference(P=0.128);among 254 children with B-ALL,52 cases(20.63%)were positive for FCM and 4 cases(1.59%)were positive for CC,with a statistically significant difference(P=0.001).4.Comparing the results of CSF tests in children with different CNS status,in 295 children with CNSL-1 status,39 cases were positive for FCM,while all CC tests were negative.The ROC curves were plotted to compare the sensitivity of FCM and CC methods in diagnosing CNSL in different CNS grading states.The area under the curve of cerebrospinal fluid FCM in CNS-2 and CNS-3 states was significantly larger than that of CC assay(0.912:0.588),and the difference was statistically significant(P=0.034).5.In 41 children with T-ALL,15 cases(36.59%)were positive for FCM,and in 252 children with B-ALL,52 cases(20.47%)were positive for FCM,with a statistically significant difference in the positive rate(P=0.025).In 142 children in the standard risk group,9 cases(6.34%)were positive for FCM,in 119 children in the intermediate risk group,29 cases(24.37%)were positive for FCM,and in 68 children in the high risk group,29 cases(42.65%)were positive for FCM,with statistically significant differences between groups(P<0.001).Among 251 children with a peripheral blood cell count<30×109/L,40 cases(15.94%)were positive for FCM,among 50 children with a peripheral blood cell count between 30×109/L and 100×109/L,14 cases(28.00%)were positive for FCM,and among 28 children with a peripheral blood cell count>100×109/L,13 cases(46.43%)were positive for FCM,The difference between groups was statistically significant(P=0.001).6.There were no statistically significant differences in gender,age,cranial computed tomography(CT)and electroencephalography among the children with CNSL diagnosed with positive cerebrospinal fluid FCM test(P>0.05).7.Comparing the results of cerebrospinal fluid FCM assay among different leukemia fusion gene subgroups,the difference of positive rate was statistically significant(P=0.045).When the gene negative group was compared with other groups separately,the differences were statistically significant(P<0.05)with the MLL-AF4,SIL-TAL1,and TEL-AML 1 gene groups.For the BCR-ABL and E2A-PBX1 gene groups,the differences were not statistically significant(P>0.05).Conclusion:1.Cerebrospinal fluid FCM is an important diagnostic method in the clinical diagnosis of CSNL in children.It has higher sensitivity compared with cerebrospinal fluid CC and can provide an objective basis for early treatment,disease assessment and improved prognosis.2.When a child is diagnosed with T-ALL,has a peripheral blood leukocyte count higher than 30 X 109/L at the time of initial diagnosis,or is assessed to be at intermediate risk or higher,the child’s probability of developing CNSL is greatly increased,which requires the combined application of FCM and CC methods to dynamically monitor the child’s CSF.3.The presence of positive MLL-AF4 and SIL-TAL1,fusion genes increases the probability of developing CNSL in children and requires high attention.