Primary central nervous system (CNS) lymphoma is a disease in which malignant (cancer) cells form in the lymph tissue of the brain and/or spinal cord.
Lymphoma is a disease in which malignant (cancer) cells form in the lymph system. The lymph system is part of the immune system and is made up of the lymph, lymph vessels, lymph nodes, spleen, thymus, tonsils, and bone marrow. Lymphocytes (carried in the lymph) travel in and out of the central nervous system (CNS). It is thought that some of these lymphocytes become malignant and cause lymphoma to form in the CNS. Primary CNS lymphoma can start in the brain, spinal cord, or meninges (the layers that form the outer covering of the brain). Because the eye is so close to the brain, primary CNS lymphoma can also start in the eye (called ocular lymphoma).