2. All patients with the exception of those with primary brain tumors, must have histologic diagnosis of systemic malignancy. Patients must have the presence of malignant cells in CSF (+CSF) or clinical signs and symptoms of leptomeningeal disease and radiographic abnormalities without malignant cells identified in the CSF (-CSF). Clinical signs/symptoms include cerebral hemispheric, cranial nerve, and/or spinal cord/root dysfunction.