Comparison of CSF cytology and spinal magnetic resonance imaging in the detection of leptomeningeal disease in pediatric medulloblastoma or primitive neuroectodermal tumor

purpose: Leptomeningeal disease (LMD) significantly affects the prognosis and treatment of pediatric patients with medulloblastoma: or primitive neuroectodermal tumor (PNET). Examination of CSF for malignant cells, detection of LMD on spinal magnetic resonance imaging (MRI), or both are the methods routinely used to diagnose LMD. A recent study suggested 100% correlation between CSF and MRI findings in children with medulloblastoma. To determine the validity of this hypothesis, we compared the rate of detection of LMD between concurrent lumbar CSF cytology and spinal MRI per formed at diagnosis in patients with medulloblastoma or PNET. Patients and Methods: As a part of diagnostic staging, 106 consecutive patients newly diagnosed with medulloblastoma or PNET were evaluated with concurrent lumbar CSF cytology and spinal MRI. CSF cytology wets examined for the presence of malignant cells and spined MRI wets reviewed independently for the presence of LMD. Results: Thirty-four patients (32%) were diagnosed with LMD based on CSP cytology, spinal MRI, or both. There were 21 discordant results, Nine patients (8.5%) with positive MRI had negative CSF cytology. Twelve patients (11.3%) with positive CSF cytology had negative MRIs. The exact 95% upper bounds on the proportion of patients with LMD whose disease would have gone undetected using either CSF cytology or MRI as the only diagnostic modality were calculated at 14.4% and 17.7%, respectively Conclusion: With the use of either CSF cytology or spinal MRI alone, LMD would he missed in up to 14% to 18% of patients with medulloblastoma or PNET. Thus, both CSF cytology and spinal MRI should routinely be used to diagnose LMD in patients with medulloblastoma or PNET. (C) 1999 by American Society of Clinical Oncology.