Diagnosing lymphoproliferative disorders involving the cerebrospinal fluid: increased sensitivity using flow cytometric analysis.

Flow cytometric immunophenotypic analysis (FCA) can be performed to evaluate lymphoid cells in cerebrospinal fluid (CSF). We compared this method with conventional cytologic diagnosis to determine its utility. A retrospective comparison of 35 consecutive CSF flow cytometry results with the corresponding cytologic diagnoses was undertaken. Twenty-five of 35 CSFs (71%) were successfully analyzed by flow cytometry. The 10 samples which could not be analyzed were either too old (greater than 3 days) or had an insufficient number of cells. A total of 9 lymphomas was detected: 4 by both flow cytometry and cytology; 2 by cytology alone; and 3 by flow cytometry alone. This represents a 50% increase in the detection of lymphoproliferative disorders in CSF by a combination of flow cytometry and cytology vs. cytology alone. Furthermore, in 3 cases with follow-up where the cytologic diagnosis was "atypical cells of undetermined significance" and the flow cytometric findings were negative for malignancy, the clinical course confirmed a benign pleocytosis in all three. We conclude that flow cytometric analysis markedly improves sensitivity when used in combination with cytology in the evaluation of lymphoid cells in CSF. Copyright 2000 Wiley-Liss, Inc.