Flow chart of management of PCNSL from presentation to therapeutic decision in ordinary clinical practice. MRI indicates magnetic resonance imaging; CT, computerized tomography; CSF, cerebrospinal fluid; LDH, lactate dehydrogenase serum level; and ADC, average diffusion coefficient. Deep regions refers to basal ganglia, corpus callosum, periventricular areas, brain stem, and/or cerebellum. (1) Ocular examination should include slit-lamp examination, indirect ophthalmoscopy,and ophthalmic ultrasonography. (2) Cerebrospinal fluid evaluation should include cell counts, protein and glucose levels, cytology, flow cytometry, and IgHV gene rearrangement studies.