What is Primary CNS Lymphoma?

Medically Reviewed by Melinda Ratini, MS, DO on February 18, 2024
3 min read

Primary central nervous system (CNS) lymphoma is a rare type of non-Hodgkin’s lymphoma (cancer of the lymphatic system). Your CNS is made up of the brain, its outer covering, and the spinal cord.

The lymphatic system is a key part of your immune system. It’s made up of many parts but includes your spleen, tonsils, bone marrow, and lymph nodes. Special white blood cells called lymphocytes fight off infections in your CNS. If these cells become cancerous, they can cause lymphoma to form there. (It also can start in the eye, since the eyes are so close to the brain. This is called ocular lymphoma).

Primary CNS lymphoma is rare. Men are more likely to get it than women, and the median age of people who are diagnosed is 55. However, people with AIDS who get this type of cancer are often much younger, often in their mid-30s.

Doctors don’t know exactly what causes primary CNS lymphoma, but some things can make it more likely:

  • Your immune system is weakened by an immune disorder, like AIDS.
  • You’re taking drugs to suppress your immune system because you’ve had an organ transplant.

Depending on where the tumor is, the symptoms can include:

Your doctor will perform tests to check your brain, spinal cord, and eyes if they suspect you may have primary CNS lymphoma. They may do some of the following:

  • Physical exam. Your doctor will check your body for any signs of disease and ask about your medical history.
  • Neurological exam. This tests your brain, spinal cord, and nerve function. This includes a series of questions about your coordination, senses, mental processes, and more.
  • Slit-lamp eye exam. Your doctor will look inside your eye using a bright, narrow beam of light and a microscope.
  • MRI. This takes a detailed picture of the inside of your brain and spinal cord. You may be injected with something that makes any cancer cells appear brighter in the image.
  • PET scan. This imaging method helps your doctor look for cancer cells in your body.
  • Lumbar puncture. Your doctor will insert a needle into your spine and take a sample of fluid. It will be examined under a microscope for cancer cells or anything else that doesn’t look right.
  • Stereotactic biopsy. Your doctor takes tissue from a tumor with the help of a computer and 3-D scanning device to pinpoint it. A number of different lab tests can be done on the sample.
  • Complete blood count (CBC) with differential. This is a test that checks on the overall health of your blood. Your doctor might order other kinds of blood tests, too.

The kind of treatment you need for primary CNS lymphoma will depend on things like your overall health and how advanced your cancer is. It can include:

  • Chemotherapy. This is usually the first treatment. Cancer-fighting drugs are injected into your body through a vein. It can also be injected into the fluid that surrounds the brain and spinal cord.
  • Radiation therapy. X-rays or other types of radiation kill the cancer cells or stop them from growing. External radiation is used for primary CNS lymphoma. It involves a machine that beams radiation to your entire brain.
  • Steroid therapy: In some cases, doctors use a type of steroid drug called a glucocorticoid. It helps reduce swelling caused by the disease.
  • Stem cell transplant. This may be offered to some younger, otherwise healthy patients whose CNS lymphoma has responded to chemotherapy.