DISEASE CHARACTERISTICS: Histologically confirmed malignancy that is metastatic to the CSF or leptomeningeal/subarachnoid space, including the following: Leukemia Lymphoma Germ cell tumors Persistent or recurrent disease required Cytologic evidence of malignancy in CSF or evidence of leptomeningeal tumor by CT or MRI No obstructive hydrocephalus or complete block of spinal CSF pathways on pre- study MRI or CT No rapidly progressing or deteriorating neurological deficit