Clinical features:
(1) rapidly progressive dementia
(2) unsteadiness of gait
(3) cranial nerve palsy
(4) personality changes
Findings on imaging studies:
(1) diffuse infiltration in the white matter of the brain on MRI T2 weighted images, with bilateral involvement of cerebral hemispheres, brainstem, basal ganglia and thalamus. These areas do not show gadolinium contrast enhancement.
(2) FDG-PET scanning shows hypermetabolism
(3) later the more typical nodular lesions with contrast enhancement may develop
Laboratory testing:
(1) flow cytometry on CSF may show a monoclonal population
(2) all studies for infectious agents are negative
(3) brain biopsy shows a lymphomatous infiltrate
Differential diagnosis:
(1) Binswanger's disease (FDG-PET shows hypometabolism)
(2) leukoencephalopathy
(3) encephalomyelitis
(4) autoimmune encephalitis in SLE or Sjogren's syndrome
