Is flow cytometry useful in determining central nervous system involvement in patients with hematological malignancy? Analysis with a prospective cohort.

Central nervous system (CNS) involvement occurs in approximately 5-15% of patients in hematological malignancies. Early diagnosis and treatment is essential for a successful approach to CNS involvement. The gold standard method for diagnosis is cytological evaluation, but its sensitivity is low. Flow cytometry (FCM) from cerebrospinal fluid(CSF) is another method used to identify small groups of cells with abnormal phenotype. In our study, we compared FCM and cytological findings in the evaluation of CNS involvement in our patients with hematological malignancies. 90 patients [58 males, 32 females] were included in the study. CNS involvement was positive in 35(%38.9) patients, negative in 48(%53.3) patients, and suspicious (atypical) in 7(%7.8) patients by flow cytometry and it was positive in 24(%26.7) patients, negative in 63(%70) patients, and atypical in 3(%3.3) patients by cytology. While the sensitivity and specificity were found to be respectively 68.5% and 100% by cytology, it was found to be 94.2% and 85.4% by flow cytometry. Flow cytometry, cytology and MR findings were significantly correlated with each other in both prophylaxis (p < 0.001) and patients with prediagnosis of CNS involvement. Although the gold standard diagnostic method in the diagnosis of CNS involvement is cytological, its sensitivity is low and it can give false negative results at a rate of 20-60%. Flow cytometry is an ideal objective and quantitative method for identifying small groups of cells with abnormal phenotype. Flow cytometry can be used routinely in the diagnosis of CNS involvement in patients with hematological malignancies with cytology, since it can detect fewer malignant cells, has a higher sensitivity, and provides easy and faster results.