Accuracy of flow cytometry and cytomorphology for the diagnosis of meningeal involvement in lymphoid neoplasms: A systematic review.

Central nervous system (CNS) involvement by lymphoid neoplasms is a relatively infrequent event that demands accurate identification. The purpose of this article is to review studies comparing diagnostic accuracy of flow cytometry (FCM) and cytomorphology (CM) for meningeal involvement from lymphoid neoplasms. Primary publications from the last 26 years were identified searching MedLine, Scopus, and Web of Science and systematically scanning bibliographies of identified articles. Only studies reporting complete results were included. We assessed study quality using the QUADAS-2 tool. For each study, we extracted informations regarding study population, technical details about sample preparation, data analysis, and results. Twenty-seven studies were included. A great heterogeneity regarding study populations and analytical procedures was observed among studies. Percentages of samples giving a positive result with both FCM and CM range from 0.3% to 42.9% among studies, whereas double negative samples go from 0% to 96.3%. Samples with positive FCM but negative CM are reported by 89% (24/27) of the studies with rates ranging from 3.5% to 61.5% of total specimens. On the contrary, samples with positive CM and negative FCM are found in 48% (13/27) of the studies with percentages ranging from 0.5% to 10%. Despite all the differences observed among studies, almost all of them state that employing flow cytometry along with conventional cytology increases the number of positive CSF samples for lymphoma involvement, although a few cases remain in whom only morphology can correctly identify malignant cells. Diagn. Cytopathol. 2016;44:841-856.