Lymphoid and myeloid neoplasms involving cerebrospinal fluid: comparison of morphologic examination and immunophenotyping by flow cytometry.

We studied 53 samples of cerebrospinal fluid (CSF) by cytologic examination and immunophenotyping by flow cytometry. The samples were taken from 43 patients; 25 had a previous diagnosis of malignant lymphoma/leukemia and the remaining 18 a variety of other diseases involving the central nervous system (CNS). Lymphoma/leukemia was detected in 21 samples: 12 by morphologic examination and immunophenotyping and nine by immunophenotyping alone. There were two cases with a suspicious morphologic examination and negative immunophenotyping in which the final diagnosis were cryptococcal and viral meningitis. In the group of 18 patients, one was diagnosed as a primary malignant lymphoma of the CNS and was positive with cytology and immunophenotyping. The other 17 were negative with both methods and follow-up showed no evidence of lymphoma/leukemia. This study shows that morphologic examination combined with flow cytometry enhances the detection rate by 75% over morphologic examination alone in CSF samples.