Intraaxial / Primary CNS Lymphoma

Pre-contrast CT	Post-contrast CT

Extraaxial(dural) / Secondary (Metastatic) CNS Lymphoma

Sagittal pre-contrast T1W MR	Sagittal Gd Enhanced MR

WHO Grade IV

Cell of Origin: Lymphocytes, usually B-cell lineage

Synonyms: PCNSL, Primary cerebral lymphoma

Common Locations: Basal ganglia, periventricular, gray-white junction. May involve corpus callosum. Rarely may arise in leptomeninges.

Demographics: Most frequent in 5th or 6th decade in non-AIDS cases. Some series show male predominance of up to 2:1. Increased incidence in immune-suppressed, including AIDS, transplantation, and other neoplasms. May express Epstein-Barr virus surface markers.

Clinical Presentation: Variable presentation, including focal neurologic deficit, increased intracranial pressure, cognitive dysfunction, seizures.

Histology: Infiltrative lesions with patchy cellularity characterized by angiocentricity and angioinvasion. Round lymphocytes with large round nuclei with prominent nucleoli.

Special Stains: Epstein-Barr virus PCR positivity demonstrated in PCNSL arising in immunocompromised patients.

Progression: Rapid growth, especially in association with AIDS. Local recurrence and CSF dissemination common.

Radiology: Iso- to slightly hyperdense on CT; may be iso- or hypointense on T2-weighted MR images. Single or multiple, homogeneously or ring-enhancing lesions. Subependymal, callosal, or CSF spread best demonstrated by MR.

Comments: Dramatic increase in incidence in recent decades only partially attributable to AIDS-related cases.