Central nervous system involvement in haematolymphoid malignancies – Role of cerebrospinal fluid cytology in the diagnosis

Context: In patients with haematological malignancies (HMs), the worst prognosis is associated with cases having central nervous system (CNS) involvement. Cerebrospinal fluid (CSF) analysis is of utmost importance for the detection of CNS involvement and for adequate treatment. Aims: The aim of the study was to determine the occurrence of CNS involvement and to study cytomorphological features of CSF in diagnosed cases of haematolymphoid malignancies. Settings and Design: All cases of haematolymphoid malignancies that underwent CSF cytology at our institute, from October 2021 to October 2024. Subjects and Methods: CSF sample from patients with haematolymphoid malignancies were studied. The cells were examined under microscope and classified as malignant or non-malignant based on their cytomorphology and further categorized as CNS1, CNS2 and CNS3 according to Children’s Oncology Group classification system. Steinherz-Bleyer algorithm was applied in cases with traumatic lumbar puncture (TLP) (>10 erythrocytes/μL). Results: CSF analysis was done in 115 cases of HMs. CNS 1 status was diagnosed in 85.8% of patients, CNS2 in 2.6% and CNS 3 in 11.5% of cases. 8 cases among CNS1 were found to have meningitis. Sixteen cases showed the presence of blasts in CSF (CNS2 and CNS3). Out of these cases, nine were acute lymphoblastic leukaemia (ALL) ([7] B cell-ALL and [2] T cell-ALL), two cases were acute myeloid leukaemia (AML), three cases were non-Hodgkin lymphoma and one case each of Waldenstrom macroglobulinemia and multiple myeloma. Conclusions: CNS involvement is frequently encountered in haematolymphoid malignancies, either at the time of initial presentation or as relapse. The study concludes that ALL has higher chances to develop CNS leukaemia.