Diagnostic Accuracy of Cerebrospinal Fluid (CSF) Cytology in Metastatic Tumors: An Analysis of Consecutive CSF Samples

BACKGROUND Cerebrospinal fluid (CSF) examination can be used to verify the presence of primary malignancies as well as cases of central nervous system (CNS) metastasis. Because of its importance, there have been several studies concerning the sensitivity of CSF cytology. To determine the practical use and reproducibility of diagnoses based on CSF cytology, we evaluated this test by analyzing cytology results from consecutive CSF samples. METHODS Between July 2010 and June 2013, 385 CSF cytology samples from 42 patients were collected. The samples were gathered using a ventricular catheter and reservoir. CSF cytology of all patients was examined more than two times with immunocytochemistry for cytokeratin. RESULTS Primary neoplastic sites and histologic types of patients' metastatic cancer were diverse. The overall sensitivity for detecting malignancy was 41.3%. Even within short-term intervals, diagnoses frequently changed. CONCLUSIONS Our results were inconsistent, with low sensitivity, when compared to the results of previous studies. However, CSF evaluation can still provide valuable diagnostic and prognostic information because adjuvant treatments are now routinely performed in patients with CNS metastasis. Negative CSF cytology results should not be ignored, and continuous CSF follow-up is essential for following the clinical course of patients with metastatic cancer involving the CNS.