Clinical significance of occult cerebrospinal fluid involvement assessed by flow cytometry in non-Hodgkin's lymphoma patients at high risk of central nervous system disease in the rituximab era.

Background And Aim: Flow cytometry (FCM) analysis of cerebrospinal fluid (CSF) is more sensitive than conventional cytology (CC) for diagnosis of lymphomatous meningeosis, but the clinical significance of occult central nervous system (CNS) disease (positive FCM with negative CC) remains unknown.

Patients And Methods: CSF samples from 105 patients with newly diagnosed aggressive lymphomas at high risk of CNS involvement were prospectively studied by both CC and FCM, and results were correlated with cumulative incidence of CNS relapse and overall survival (OS). Patients were divided into three groups: 1) patients without CNS involvement (CC-/FCM-; n=83); 2) individuals with occult CNS disease (FCM+/CC-; n=15); and 3) cases with CNS disease (CC+/FCM+; n=7).