ESCCA / ISCCA protocol for the analysis of cerebrospinal fluid by multiparametric flow‐cytometry in hematological malignancies

Flow cytometry for meningeal infiltration in B acute lymphoblastic leukemia in a low middle income country

Meningeal infiltration in children with B acute lymphoblastic leukemia is one of the most serious complications. Timely diagnosis not only significantly enhances treatment efficacy but also leads to improve patient outcome and reduce risk of relapse. This is particularly crucial in low to middle income countries facing health constraints, where optimizing resources is essential. Conventional cytology (CC) study of cerebrospinal fluid (CSF) is considered in different countries to be the Gold-standard despite its low sensitivity (< 50%). The study of CSF by multiparametric flow cytometry (MFC) appears to be an alternative. The aim of our study was to assess MFC analytical performance compared with CC. Our cross sectional study was conducted over a six-month period in the biological hematology department. CSF samples underwent analysis for the presence of blasts using both CC and MFC. Cytological slides of the CSF were prepared by cytocentrifugation in a Shandon Cytospin 4™. Flow cytometric analysis was performed on the BD FACSLyric™ flow cytometer. All statistical analyses were performed using SPSS version 21.0 (SPSS Inc.). Agreement between the two methods was made using the Kappa index and χ2 test. This study was approved by the local ethics committee. Sixty CSF samples from 39 children with B acute lymphoblastic leukemia were analyzed. Meningeal infiltration was detected respectively in 20% of cases by MFC and 5% of cases by CC, with a significant difference p = 0.006. Comparing the two methods, the Kappa coefficient was 0.35, indicating weak agreement between the two methods. Moreover, MFC positivity was higher even for hypocellular samples. Of the 51 hypocellular samples, eight were positive by MFC while they were negative by CC. MFC shows better sensitivity while retaining good specificity for the detection of meningeal involvement. MFC could therefore be a complementary method to CC for detecting blast cells in the central nervous system.

Initial and follow-up evaluations on cerebrospinal fluid involvement by hematologic malignancy

Central nervous system (CNS) involvement is a serious complication in hematologic malignancy, and early detection and management of CNS involvement in these cases significantly impact the prognosis. Currently, there is no consensus on the use of multiparametric flow cytometry (MFC) and conventional cytology (CC) testing for initial and follow-up cerebrospinal fluid (CSF) specimens to diagnose CNS involvement by hematologic malignancy. In our institution, after initial MFC and CC, two subsequent negative MFCs are required before discontinuing MFC. The aim of this study is to evaluate the outcome of this approach. CSF cytology and MFC reports were retrieved from Laboratory Information System, and data was reviewed. Between January 2020 and December 2021, 1789 CSF samples from 280 patients were submitted for CSF analysis. For those 517 CSF samples tested by both MFC and CC, 97 cases tested positive by both MFC and CC with 95% concordance. Eighteen cases were MFC + /CC - and 7 were MFC - /CC + . Thirty-six cases had initially positive MFCs followed by more than one MFC evaluation. Among those 36 cases, 22 cases (61.1%) converted to negative after the second follow-up sample, 9 cases (25%) were continuously positive for at least three samples, and 5 cases (13.9%) exhibited negative to positive conversion. Compared to negative CSF cases, positive CSFs had higher total nucleated cell count and higher total protein levels while red blood cells, glucose, and lactate dehydrogenase levels remained at comparable levels. The concordance between MFC and CC was excellent. The high incidence of positive MFCs on two or more follow-up samples and the high frequency of negative MFC to positive conversion indicate the necessity of repeated negative MFCs before discontinuing MFC. The fact that more than half of the positive cases converted to negative after the second CSF specimen and most follow-up positive cases can be detected by CC alone suggests it is adequate to use CC alone for follow-up CSF study after two consecutive negative MFCs.

Value of cerebrospinal fluid white cell count and protein level in predicting leptomeningeal involvement by systemic aggressive B-cell lymphoma

INTRODUCTION

Diagnostic cerebrospinal fluid (CSF) analysis for patients with newly diagnosed aggressive B-cell lymphoma at risk of secondary central nervous system involvement typically includes multiparametric flow cytometry (MFC), cytology (CC), white cell count (WCC) and total protein. The strength of relationships between MFC results and the remaining variables has been disputed in small studies. We explored these relationships in a large homogeneous cohort of patient samples, aiming to establish the relationship between WCC and protein level and MFC results.

METHODS

Adult patients with aggressive B-cell lymphoma at risk of CNS involvement who underwent staging CSF analysis by MFC were identified retrospectively from institutional electronic records between October 2011 and December 2020.

RESULTS

Three hundred and seventy eight samples, including 45 (11.9%) MFC+ samples, were analysed. The relative sensitivity of CC for MFC positivity was 0.38, with PPV of 0.68. Significantly higher median WCC (p < .001) and protein levels (p = .011) were seen in MFC+ vs. MFC- samples. MFC + CC+ (vs. MFC + CC- samples) demonstrated higher median neoplastic events and neoplastic cell concentration. WCC ≥36 × 10⁶ /L and protein ≥1.12 g/L cut-off values demonstrated the highest PPVs for MFC positivity (0.67 and 0.88, respectively).

CONCLUSIONS

Statistically significant associations exist between elevated WCC and protein and MFC positivity, and selected WCC and protein cut-off values have PPVs comparable to that of cytological assessment. Whilst routine WCC and protein analysis may be unnecessary, WCC/protein values above these levels could be regarded as reasonable evidence of CSF involvement in the appropriate setting.

Central nervous system (CNS) involvement has an adverse impact on survival in newly diagnosed adult acute lymphoblastic leukemia (ALL) assessed by flow cytometry

The role of CNS involvement detected by flow cytometry (FCM) in patients with acute lymphoblastic leukemia has been discussed previously; however, its impact on survival has not been described enough. We analyzed a retrospective cohort of newly diagnosed ALL adult patients who had a cerebrospinal fluid (CSF) analysis by FCM and conventional cytology. We evaluated 81 patients; 19 (23.4%) were only positive by FCM, five (6.3%) were double-positive (DP) and 57 (70.4%) were double-negative (DN). The detection of CNS involvement was increased from 6% to 24%, employing FCM; In our final analysis, patients with FCM + had a lower survival of 7.01 months [95% CI (5.90-8.24)], compared with 11.71 months [IC95% (9.49-13.94)] in the DN group (p = 0.03).