A comparison between ventricular and lumbar cerebrospinal fluid cytology in adult patients with leptomeningeal metastases

Leptomeningeal metastases (LMs) are common metastatic complications, occurr ing in at least 5% of patients with disseminated cancer. Cerebrospinal flui d (CSF) cytology remains the standard for diagnosis and assessment of treat ment response, but may be inadequate. Our objective was to compare ventricu lar and lumbar CSF cytology in patients who had cytologically proven LM and were receiving intra-CSF chemotherapy. Sixty patients with LM, positive lu mbar CSF cytology documented at diagnosis, limited extent of CNS disease, a nd no evidence of CSF flow obstruction were treated with a variety of intra -CSF chemotherapies. All patients underwent a single simultaneous ventricul ar and lumbar CSF sampling (mean volume of CSF per site examined, 10 ml) to assess response to therapy at either 1 or 2 months after treatment initiat ion. Ventricular CSF cytology was positive in 44 patients (73%), 35 of whom were also positive by lumbar CSF cytology. Lumbar CSF cytology was positiv e in 45 patients (75%), of which 35 were also positive by ventricular CSF c ytology. Samples were negative at both ventricular and lumbar sites in 6 pa tients (10%). Paired CSF cytologies were discordant in 19 (32%) patients. T he lumbar cytology was negative in 9, whereas the ventricular cytology was positive (lumbar false-negative rate of 17%); the ventricular cytology was negative in 10, whereas the lumbar cytology was positive (ventricular false -negative rate of 20%). In the presence of spinal signs or symptoms of LM, the lumbar CSF cytology was more likely to be positive than was the ventric ular (odds ratio = 2.86; 95% confidence interval, 0.86-9.56). Conversely, i n the presence of cranial signs or symptoms, the ventricular CSF cytology w as more likely to be positive than was the lumbar (odds ratio = 2.71; 95% c onfidence interval, 0.76-9.71). In this cohort of patients, whose LM was do cumented initially by positive lumbar CSF cytology, ventricular and lumbar CSF samples obtained during treatment had similar false-negative rates, dep ending on the site of clinical or radiologic disease. This suggests that bo th lumbar and ventricular sites must be sampled when assessing treatment re sponse. If clinical or radiographic disease is present only at 1 site, then CSF from that site is more likely to be positive than is CSF obtained from the more distant site.