Primary CNS lymphoma.

Non-Hodgkin's lymphoma invades the brain, the vitreous body and nerves of the eye, the meninges, and the nerve roots of brain and spine, leading to the development of a primary CNS lymphoma. The mechanism of involvement of these locations by malignant B lymphocytes is unknown, but it might involve molecular targeting of lymphoma cells generated at cryptic systemic sites. The diagnosis of primary CNS lymphoma has been facilitated by advances in imaging techniques and the discovery of molecular markers. Methotrexate-based regimens, even when radiation is deferred, prolong overall survival to over 5 years, but relapses eventually occur in most cases. Better tools for earlier diagnosis and monitoring of treatment response will emerge from molecular studies of therapeutic targets.