Supplementary Material for: Assessment of the Utility of Cytology and Flow Cytometry of Cerebrospinal Fluid Samples in Clinical Practice

Objectives: We sought to assess the utility and limitations of both flow cytometry (FC) and cytology for the analysis of cerebrospinal fluid (CSF) in a practical clinical setting. Methods: A total of 393 consecutive CSF samples from 171 patients submitted for both cytomorphologic and FC assessments were analyzed. Results: Both FC and cytology findings were negative for malignancy in 315/393 samples (80%), and either positive (POS) or suspicious/atypical (SUSP/AT) in 7% of samples. This resulted in high agreement between FC and cytology (87%). Minor discrepancies were present in 4% of the cases. In 28 samples, an abnormal population was detected by FC but not by cytology. Conclusions: FC and cytology are important complementary methods for analyzing CSF samples. In cases where cytology is SUSP/AT and FC is inconclusive or negative, additional specimens should be submitted for immunostaining, cytogenetics, and/or molecular studies.