Evaluati̇on of central nervous system i̇nvolvement i̇n hematologi̇cal mali̇gnanci̇es wi̇th flow cytomery

Objective: For hematologic malignancy patients with a high risk of central nervous system (CNS) involvement, it is usually a routine procedure to examine cerebrospinal fluid as a screening test for staging or if there are symptoms and signs present indicating CNS involvement. Conventionally, cytological analysis and magnetic resonance imaging (MR) techniques are used for detecting CNS involvement. Recently, it has been shown in various studies that flow cytometric analysis (FCM) has been increasingly replacing cytological analysis which was once considered as the gold standard test. In this study, we aimed to determine efficacy of FCM analysis in diagnose of CNS involvement in patients with high-risk hematological malignancies and compared with other methods such as cytology, biochemical or radiological imaging procedures. In addition, we tried to determine its prognostic role on clinical outcomes. Material and Method: We have included 35 patients with a diagnosis of high-risk hematologic malignancy who were on follow up in Çukurova University Medical School Balcalı Hospital Hematology and Oncology Department. We performed flow cytometric, cytological and biochemical analysis and direct microscopic examination on patient CSF specimens. Results: Median age of our study group was 43±2.9 years and M/F rate was 12/23. Twenty percent of our patients had ALL (57%), three AML (8.5% ), 11 NHL (31%), one patient CLL. Six of the NHL patients had DLBCL (54%), three had MCL (27%), one Burkitt lymphoma, one low grade NHL. While the flow cytometry was positive in 11 of the patients, cytology was positive in three of them and MR imaging was positive in five patients only. There was a statistically significant difference between cytologic and FCM analysis of CSF in detecting CNS involvement (P =0.025) which was indicating a better sensivity for FCM. There was not any significant meaningful difference between flow cytometry analysis and MR imaging findings and BOS protein levels (P >0.05). The significance between cytologic analysis and MR examination was also significant (P =0.05). Our study results demonstrated that positive FCM and cytologic analysis had correlated well with the presence of clinical symptoms (P =0.005 and P=0.001, respectively). FCM analysis was not predictive in detecting survival of the patients with CNS involvement both in the total study group and also in ALL subgroup (P>0.05). Overall survival rate of our study population was 52.7% ±11.5 with a median follow up of 18 months. Conclusion: Flow cytometric diagnosis of CNS involvement predominates compared to other methods such as cytological and biochemical analysis, radiological imaging in hematological malignancies. Despite cytological examination still maintains its clinical significance, sensitivity of this method seems to be low in detecting CNS involvement. Thus decisions should made in a combined manner, taking into consideration both FCM and cytology results. More studies with a larger patient population and a longer follow up are needed in order to guide us about the prognosis. Keywords: Hematological malignancy, Flow cytometry, Central nervous system involvement.