10293- ML-18 FLOW CYTOMETRY IS EFFECTIVE FOR THE RAPID DIAGNOSIS OF PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA

Abstract INTRODUCTION Primary central nervous system lymphoma (PCNSL) is characterized by an extremely high proliferation rate, making early diagnosis and therapeutic intervention crucial. To facilitate rapid diagnosis, our hospital has implemented flow cytometry (FCM) in addition to conventional histopathological methods. We evaluated the effectiveness of FCM for the rapid diagnosis of PCNSL. METHODS From 2010 to 2023, we retrospectively analyzed 67 consecutive patients with suspected PCNSL based on preoperative imaging findings, in whom FCM was performed using intraoperative specimens. B cell clonality was determined when CD19 or CD20 was expressed in 20% or more and the κ/λratio was either >3.0 or <0.5. RESULTS Pathological diagnosis confirmed PCNSL in 42 cases, all of which were diagnosed as diffuse large B-cell lymphoma (DLBCL). Six cases (14.3%) of PCNSL patients were discordant with FCM (FCM-D). In contrast, all cases of other tumor types were FCM-D. The sensitivity and specificity of FCM were 85.7% and 100%, respectively. Additionally, T cell surface markers such as CD3, CD4, CD5, and CD8 were significantly elevated in the FCM-D group of PCNSL patients (p<0.01). DISCUSSION FCM results can be obtained within a few hours after tissue collection. With a specificity of 100%, FCM provides a reliable basis for early therapeutic intervention and is anticipated to improve postoperative Karnofsky Performance Status (KPS) and overall survival (OS) in the future. The FCM-D cases among PCNSL patients may have indicated the infiltration of T lymphocytes. Sensitivity could potentially be improved by analyzing multiple samples with FCM. CONCLUSION FCM can serve as a reliable basis for the rapid diagnosis and therapeutic intervention of PCNSL patients.