Primary CNS lymphoma.

Primary CNS lymphoma, an uncommon form of extranodal non-Hodgkin's lymphoma, has increased in incidence and occurs in both immunocompromised and immunocompetent hosts. Primary CNS lymphoma in immunocompetent patients is associated with unique diagnostic, prognostic and therapeutic issues and the management of this malignancy is different from other forms of extranodal non-Hodgkin's lymphoma. Characteristic imaging features should lead to suspicion of the diagnosis, avoidance of corticosteroids (if possible) and early neurosurgical consultation for stereotactic biopsy. Since primary CNS lymphoma may involve the brain, cerebrospinal fluid and eyes, diagnostic evaluation should include assessment of all of these regions as well as screening for the possibility of occult systemic disease. Resection provides no therapeutic benefit and should be reserved for the rare patient with neurological deterioration due to brain herniation. Whole-brain radiation therapy alone is insufficient for durable tumor control and is associated with a high risk of neurotoxicity in patients over 60 years of age. Neurotoxicity is typically associated with significant cognitive, motor and autonomic dysfunction and has a negative impact on quality of life. Chemotherapy and whole-brain radiation therapy together improve tumor response rates and survival compared with whole-brain radiation therapy alone. Methotrexate-based multiagent chemotherapy without whole-brain radiation therapy is associated with similar tumor response rates and survival compared with regimens that include whole-brain radiation therapy, although controlled trials have not been performed. The risk of neurotoxicity is lower in patients treated with chemotherapy alone. The incidence of HIV-related primary CNS lymphoma has decreased in the era of highly active antiretroviral therapy. Patients with HIV-associated primary CNS lymphoma have a worse prognosis but may respond to highly active antiretroviral therapy, whole-brain radiation therapy or therapies directed against the Epstein-Barr virus.