A rare and highly aggressive lymphoma confined to the CNS and is of diffuse large B-cell histology in over 90% of cases; the remainder are indolent B-cell lymphomas, BL, and peripheral TCLs.
The incidence of PCNSL is particularly high in the setting of HIV infection, in which it often presents with multifocal disease and is virtually always associated with EBV.
HIV-negative patients often presents with solitary (66%) intracranial masses and is almost never associated with EBV.
- Homogenously enhancing mass lesion.
- Supratentorial (87%), involvement of the frontoparietal lobes (39%), eyes (15% to 25%), CSF (7% to 42%), and in rare cases, the spinal cord are involved.
Most DLBCLs that arise in the CNS are of the ABC subtype and a high proportion have mutations in the BCR and MYD88.
Cognitive and personality changes are more common due to a predilection for involvement in the frontal lobes, corpus callosum, and periventricular area.
PET scanning may distinguish lymphoma and toxoplasmosis and obviate the need for biopsy in some AIDS patients.
Primary ocular lymphoma is part of the spectrum of CNS lymphoma, usually with DLBCL histology.
Approximately 5% to 15% of PCNSL have ocular involvement at diagnosis whereas CNS involvement may follow isolated ocular lymphoma in 50% to 80% of patients.

Prognosis

The IELSG score