Utility of Flow Cytometry in the Evaluation of Cerebrospinal Fluid in Hematolymphoid Malignancies: A Prospective Study

Abstract

Central nervous system (CNS) involvement in hematolymphoid malignancies poses a diagnostic challenge and is associated with poor prognosis. Flow cytometry (FCM) has emerged as a sensitive diagnostic tool for detecting malignant cells in cerebrospinal fluid (CSF). The objective of this study was to evaluate the diagnostic utility of FCM in CSF of patients with suspected hematolymphoid malignancies and to describe their clinicopathological spectrum. This prospective study included 42 patients from January 2024 to March 2025. CSF samples were analyzed through cytomorphology and FCM using lineage-specific panels. Statistical analyses included frequency distribution and correlation of FCM results with clinical, radiological, and bone marrow findings. The mean patient age was 22.26 ± 19.03 years. FCM detected CNS involvement in 90.4% of cases. In terms of final hematological diagnosis, B-cell acute lymphoblastic leukemia (B-ALL) was the most frequent, diagnosed in 24 patients (61.9%), followed by acute myeloid leukemia, diffuse large B-cell lymphoma, and T-cell ALL. Chronic myeloid leukemia, multiple myeloma, and Burkitt’s lymphoma were also diagnosed, although in fewer numbers. Morphologically, the presence of B-lymphoblasts was observed in 38.1% of CSF samples, making it the most common cellular abnormality. This was followed by atypical lymphoid cells (21.4%) and blastoid cells (9.5%), whereas a few samples showed plasma cells, large clonal lymphoid cells, or were reported as negative for blasts. Hence, FCM increases the sensitivity and specificity of detection significantly. FCM significantly enhances the detection of malignant cells in CSF, even in paucicellular samples, proving its utility in routine CNS evaluation in hematolymphoid malignancies.