Comparison of lumbar and shunt cerebrospinal fluid specimens for cytologicdetection of leptomeningeal disease in pediatric patients with brain tumors

Purpose: Leptomeningeal disease (LMD) significantly affects the prognosis a nd treatment of pediatric patients with primary CNS tumors. Cytologic exami nation of lumbar CSF is routinely used to detect LMD. To determine whether examination of CSF obtained from ventricular shunt taps is a more sensitive method of detecting LMD in these patients, we designed a prospective study to compare the findings of cytologic examinations of CSF obtained from con current lumbar and ventriculoperitoneal (VP) shunt taps. Patients and Methods: As a parr of diagnostic staging, follow-up testing, o r both, 52 consecutive patients underwent concurrent lumbar and shunt taps on 90 separate occasions, ranging from the time of diagnosis to treatment f ollow-up. CSF from both sites was examined cytologically for malignant cell s. Results: The median age of the 28 males and 24 females was 7.5 years (range , 0.6 to 21.4 years). The primary CNS tumors included medulloblastoma. (n = 29), astrocytoma (n = 10),ependymoma(n = 5), germinoma (n = 3), atypical t eratoid rhabdoid tumor (n = 2), choroid plexus carcinoma (n = 2), and pineo blastoma (n = 1). Each site yielded a median CSF volume of 1.0 mt. Fourteen of 90 paired CSF test results were discordant: in 12, the cytologic findin gs from shunt CSF were negative for malignant cells, but those from lumbar CSF were positive; in two, the reverse was true. Malignant cells were detec ted at a higher rate in lumbar CSF than in shunt CSF (P = .0018). When repe at analyses were excluded, examination of lumbar CSF remained significantly more sensitive in detecting malignant cells (P = .011). Analysis of the su bset of patients with embryonal tumors showed similar results (P = .0008). Conclusion: Cytologic examination of lumbar CSF is clearly superior to cyto logic examination of: VP shunt CSF for detecting leptomeningeal metastases in pediatric patients with primary CNS tumors. (C) 1999 by American Society of Clinical Oncology.