What is primary CNS lymphoma?

➢ occurs mostly as diffuse large B-cell lymphomas ➢ accounts for 2% of extranodal lymphomas and 1% of intracranial tumors. ➢ It is the most common CNS neoplasm in immunosuppressed individuals ➢ In nonimmunosuppressed populations, the age spectrum is relatively wide, with the incidence increasing after 60 years of age. ➢ aggressive disease with a relatively poor response to chemotherapy as compared with peripheral lymphomas. ➢ often multiple tumor nodules within the brain parenchyma, in perivenytricular areas; yet involvement of sites outside of the CNS is uncommon. ➢ Conversely, lymphoma originating outside the CNS rarely spreads to the brain parenchyma