Update on the management of primary CNS lymphoma.

Primary central nervous system (CNS) lymphoma is a non-Hodgkin's lymphoma restricted to the nervous system. The incidence of this lymphoma is rising in the immunocompetent population but may be decreasing in patients with the acquired immune deficiency syndrome (AIDS) due to the introduction of highly active antiretroviral therapy. A periventricular, diffusely enhancing lesion on magnetic resonance imaging (MRI) is suggestive of primary CNS lymphoma, but a stereotactic biopsy is needed to make a definitive diagnosis. Concurrent leptomeningeal and ocular involvement is common in this brain tumor. Because primary CNS lymphoma is exquisitely sensitive to steroids, these drugs should be withheld until tissue is obtained for diagnosis. Age and performance status are important prognostic factors, regardless of specific treatment. Methotrexate in high doses is the single most effective chemotherapeutic agent for primary CNS lymphoma. It substantially improves survival when combined with radiation therapy and is better than radiotherapy alone as a single agent. Multimodality treatment results in delayed cognitive neurotoxicity, particularly in older patients. New treatment protocols have focused on the use of chemotherapy alone.