A 73-year-old man presented a progressive neurologic syndrome with impairment of multiple cranial nerves, ataxia and limb weakness. Neuroradiological evaluation showed multiple supra and infratentorial lesions, which completely disappeared after steroid treatment on two occasions. These neuroradiological modifications were closely correlated with clinical picture and CSF findings. Post-mortem examination showed multifocal primary CNS immunoblastic large cell lymphoma. Immunohistochemistry showed that the tumor was of B-cell origin.