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). RESULTS: Six cases showed CNS relapse or progression: two in Group 1 (2.4%), two in Group 2 (13%) and two in Group 3 (28.5%) (Group 2 vs. 1, P=0.04; Group 3 vs. 1, P<0.001). Patients from Groups 2 (P=0.05) and 3 (P<0.001) also showed a higher cumulative incidence of CNS relapse than those from Group 1. Significant differences were observed in OS between FCM-/CC- and FCM+/CC+ cases (P=0.02), while patients with occult CNS disease (FCM+/CC-) displayed intermediate OS rates, although differences did not reach statistical significance. CONCLUSIONS: The presence of occult CNS involvement at diagnosis in patients with NHL at high risk of CNS disease is associated with a higher probability of CNS relapse.

Identification of leptomeningeal disease in aggressive B-cell non-Hodgkin's lymphoma: improved sensitivity of flow cytometry.

PURPOSE: Here, we evaluate the sensitivity and specificity of a new 11-parameter flow cytometry (FCM) approach versus conventional cytology (CC) for detecting neoplastic cells in stabilized CSF samples from newly diagnosed aggressive B-cell non-Hodgkin's lymphoma (B-NHL) at high risk of CNS relapse, using a prospective, multicentric study design. PATIENTS AND METHODS: Moreover, we compared the distribution of different subpopulations of CSF leukocytes and the clinico-biologic characteristics of CSF+ versus CSF-, patients, in an attempt to define new algorithms useful for predicting CNS disease. RESULTS: Overall, 27 (22%) of 123 patients showed infiltration by FCM, while CC was positive in only seven patients (6%), with three other cases being suspicious (2%). CC+/FCM+ samples typically had more than 20% neoplastic B cells and/or >or= one neoplastic B cell/microL, while FCM+/CC- samples showed lower levels (P < .0001) of infiltration. Interestingly, in Burkitt lymphoma, presence of CNS disease by FCM could be predicted with a high specificity when increased serum beta2-microglobulin and neurological symptoms coexisted, while peripheral blood involvement was the only independent parameter associated with CNS disease in diffuse large B-cell lymphoma, with low predictive value. CONCLUSION: FCM significantly improves the sensitivity of CC for the identification of leptomeningeal disease in aggressive B-NHL at higher risk of CNS disease, particularly in paucicellular samples.