Cerebrospinal fluid from patients with hematopoietic neoplasms: the need for an integrated approach

Cerebrospinal fluid (CSF) evaluation plays an increasing role in the diagnosis and staging of hematopoietic neoplasms. The evaluation is based on the cytomorphologic evaluation (CE) of the specimen and flow cytometry study (FCS). The impact of the increased sensitivity of multicolor FCS and its correlation with the morphological analysis of CSF needs to be evaluated to better guide clinical management.

CSF specimens sent for CE and FCS obtained over a 9-month period were retrospectively analyzed. Cases were considered completely discordant if one method detected an abnormal hematologic population and the corresponding method was negative and partially discordant if FCS detected an abnormal hematologic population and the CE was atypical or suspicious. Root cause analysis of these discrepancies was performed.

A total of 78 of 361 cases (22%) had discordant results; 72 cases were from patients with hematopoietic neoplasms-22 cases were completely discordant and 50 were partially discordant. FCS had a sensitivity of 95.3% and a specificity of 98.1% for detecting abnormal hematopoietic populations. CE rendered a positive diagnosis in 17.6% of cases with a specificity of 100%.

Our series demonstrates evaluation of CSF involvement by hematopoietic malignancy with FCS is more sensitive than and equally specific as CE. Nonetheless, CE remains one of the mainstays in the evaluation of CSF specimens. Optimizing cytologic evaluation through process modifications including decreasing screening area and evaluation of multiple preparations increased the detection rate of malignant cells. As such, optimal CSF evaluation and integration FCS is critical in patient management.