Ten antibodies, six colors, twelve parameters: a multiparameter flow cytometric approach to evaluate leptomeningeal disease in B-cell non-Hodgkin's lymphomas.

Background: Flow cytometry (FC) is considered a sensitive and specific technique for the detection of occult lymphoma cells in cerebrospinal fluid (CSF).

Methods: The diagnostic sensitivity of a FC approach which uses a combination of 10 antibodies, a single-tube evaluation, and a six-color instrument, was evaluated and compared to conventional cytology (CC) for the detection of lymphomatous cells in the CSF of 44 patients affected by B-cell non-Hodgkin's lymphoma (B-NHL) considered at high risk of central nervous system spread.

Results: The CSF obtained from 36 newly diagnosed and 8 relapsed patients affected by B-cell lymphoma was assessed by FC and CC on a total of 62 samples; 52/62 (82.6%) were considered paucicellular as they had fewer than 10 cells/μl. All cases were evaluated by both methods. FC gave 15/62 (24%) positive results, CC 10/62 (16%) positive results; none of the samples evaluated had a positive CC with a negative FC result.

Conclusions: The use of a multiparameter FC approach, which collects an elevated number of monoclonal antibodies in a single tube and identify different cell populations with a selective gating strategy analysis, allows for the evaluation of lymphocyte subsets and the detection of leptomeningeal disease in B-NHL, even in the presence of paucicellularity of samples.