Central Nervous System Lymphoma.

Primary central nervous system lymphoma (PCNSL) is an uncommon subtype of extranodal non-Hodgkin lymphoma (NHL) with less than 1500 cases annually. Incidence of PCNSL has remained stable in the post-highly active antiretroviral therapy era, owing to increasing incidence in elderly, immunocompetent patients. Most PCNSL is diffuse large B cell in origin, with less frequent involvement of T-cell and Burkitt lymphoma. Secondary central nervous system lymphoma is more likely to occur in the relapsed setting of a systemic NHL. Methotrexate forms the backbone of management for prophylaxis and treatment of disease. Treatments are currently under investigation for both disease entities.