Cytologic Analysis of Malignant Tumor Cells in Cerebrospinal Fluid

Cytologic evaluation of cerebrospinal fluid(CSF) is an effective tool in diagnosing many disorders involving the central nervous system(CNS). CSF examination has been found to be of particular value in the diagnosis of metastatic carcinoma, lymphomatous or leukemic involvement of CNS and certain primary CNS tumors. As a survey of metastatic tumors to CSF and an evaluation of the preparation techniques increasing cellular yield in our laboratory, 713 CSF specimens examined between July 1995 and April 1997(1 year 10 months), were reviewed. There were 75 positive and 5 suspicious cases, the latter have had no evidence of tumors clinically. Primary tumors of 75 positive cases were classified as follows; 4(5.3%) as primary brain tumors, 40(53.3%) as secondary carcinomas, 13(17.3%) as leukemias, and 18 (24.0%) as lymphomas. The most common primary site of metastatic carcinomas was the lung in 17 cases(42.5%) followed by the stomach in 13(32.5%), breast in 8 (20.0%), and unknown primary in 2(5.0%). Four primary brain tumors were 3 cerebellar medulloblastomas and a supratentorial primitive neuroectodermal tumor (PNET). All 40 metastatic carcinomas were adenocarcinoma presented as single cells or cell clusters. Although signet ring cells were frequent in the cases of gastric primary cancers, no significant cytologic differences according to the primary site were observed. The cytologic features of leukemia and lymphoma were characterized by hypercellular smears presenting as individual atypical cells with increased N/C ratio, presence of nucleoli, and nuclear protrusions. In medulloblastomas and PNET, the principal cytologic findings were small undifferentiated cells arranged singly or in loose clusters with occasional rosettoid features. This study suggests that the CSF cytology is useful in the diagnosis of malignancy, especially metastatic extracranial tumors and the diagnostic accuracy can be improved by increasing cellular yield using cytocentrifuge.