Diagnosis

Diagnosing central nervous system (CNS) lymphoma often involves several steps. CNS lymphoma can look like other brain conditions on scans, including gliomas, brain metastases and infections. In people with weak immune systems, an infection called toxoplasmosis also can cause brain lesions that may look similar to CNS lymphoma. Because of this, several tests may be needed to confirm the diagnosis.

To find out if someone has CNS lymphoma, a healthcare professional may suggest the following:

  • Neurological exam. A neurological exam tests vision, balance, coordination, strength, reflexes and thinking skills. Any changes can help show which part of the nervous system might be involved.
  • Imaging tests. Imaging tests help create detailed pictures of the brain and spinal cord. MRI is often used. Sometimes a CT scan may be done instead. Additional imaging tests may be done to check for lymphoma in other parts of the body.
  • Biopsy. A biopsy removes a small piece of tissue from the affected area. The sample is checked in a lab for cancer cells. A biopsy is usually needed to confirm CNS lymphoma.
  • Spinal fluid tests. A lumbar puncture is a procedure to collect fluid from around the spinal cord. A lumbar puncture, also called a spinal tap, is done using a needle. A healthcare professional inserts the needle between two bones in the lower back and draws out some of the fluid that surrounds the brain and spinal cord. This fluid is called cerebrospinal fluid. The fluid goes to a lab where it's tested for cancer cells.
  • Eye exam. If there are eye symptoms, an eye specialist may perform a full exam. This can include using a microscope with a bright light, called a slit-lamp eye exam, to check for signs of lymphoma.

On MRI or CT scans, CNS lymphoma usually looks like a spot that gets brighter after contrast is used. This is called enhancement. Sometimes the outer edge looks brighter than the center, creating a ring shape called ring enhancement. These findings can suggest lymphoma, but imaging alone cannot confirm the diagnosis. A biopsy is usually needed.

Your care team also may do other tests to see if lymphoma is in other parts of the body. These tests help show if the CNS lymphoma started in the brain or spread from somewhere else, which guides treatment choices.

Staging

Many cancers use stages, such as stage 1, 2, 3 or 4, to describe how far the cancer has spread. CNS lymphoma is often described differently. Instead of focusing on numbered stages, healthcare professionals focus on where the lymphoma is found and whether it is limited to the nervous system or also involves other parts of the body.

The healthcare team uses tests to learn:

  • Where the lymphoma is located, such as the brain, the spinal cord or the fluid surrounding them, and whether it involves the eyes.
  • Whether the lymphoma started in the central nervous system or spread there from another part of the body.
  • How much the lymphoma has spread within the central nervous system.

To do this, your healthcare team may use tests to check:

  • The brain and spinal cord.
  • The eyes.
  • The fluid around the brain and spinal cord, called cerebrospinal fluid.
  • Other parts of the body, such as the lymph nodes, chest, abdomen, testicles or bone marrow.

These tests help your healthcare team understand the extent of CNS lymphoma and plan treatment. In some cases, healthcare professionals also use the Ann Arbor staging system to describe lymphoma. In that system, primary CNS lymphoma may be described as stage 1E. This means lymphoma is in one area outside the lymph nodes.

Treatment

Treatment for central nervous system (CNS) lymphoma usually begins with chemotherapy. Other treatments include immunotherapy, targeted therapy, corticosteroids, radiation therapy and chimeric antigen receptor (CAR)-T cell therapy. This also is called CAR-T cell therapy. Sometimes healthcare teams use high-dose chemotherapy followed by a bone marrow transplant, also called a bone marrow stem cell transplant to treat this cancer.

Treatment depends on the type of CNS lymphoma, your overall health, your age and how much of the central nervous system is involved. The goal of treatment is to control the cancer, ease symptoms and protect brain function.

Chemotherapy

Chemotherapy treats cancer with strong medicines. There are many chemotherapy medicines. Most chemotherapy medicines are given through a vein. Some come in pill form.

Chemotherapy is the main treatment for many people with CNS lymphoma. High doses of certain chemotherapy medicines may be used because they can reach the brain and spinal cord.

Radiation therapy

Radiation therapy treats cancer with powerful energy beams. The energy can come from X-rays, protons or other sources. During radiation therapy, you lie on a table while a machine moves around you. The machine directs radiation to precise points in your body.

Radiation therapy may be used alone or after chemotherapy to treat CNS lymphoma. Because radiation to the brain can affect memory and thinking, healthcare professionals carefully weigh the benefits and risks before recommending this treatment.

Bone marrow transplant

Sometimes healthcare professionals recommend high-dose chemotherapy followed by a bone marrow transplant, also called a bone marrow stem cell transplant, to treat CNS lymphoma. This approach may be used after the lymphoma responds to initial treatment or if the lymphoma comes back.

A bone marrow transplant replaces blood-forming cells that are damaged by high doses of chemotherapy. This helps the body recover and allows healthcare professionals to use intensive chemotherapy to treat the lymphoma.

Immunotherapy and targeted therapy

Immunotherapy and targeted therapy use medicines that help the body find and attack cancer cells. Some help the immune system recognize cancer. Others block signals that cancer cells need to grow.

These treatments may be used to treat CNS lymphoma in some cases. They may be given with chemotherapy or used if the lymphoma returns or does not respond to other therapies.

Steroids

Corticosteroids may be used to reduce swelling in the brain and ease symptoms. In some cases, these medicines may be delayed until after a biopsy is done because they can affect test results.

CAR-T cell therapy

Chimeric antigen receptor (CAR)-T cell therapy trains immune system cells, called T cells, to fight cancer. This treatment begins with removing some white blood cells, including T cells, from the blood.

The cells are sent to a lab. In the lab, the cells are treated so that they make special receptors. The receptors help the cells recognize a marker on the surface of cancer cells. Then the cells go back into the body. They can find and destroy cancer cells.

CAR-T cell therapy may be an option for some people with primary CNS lymphoma that has not improved with other treatments, known as refractory disease. It also may be used if the lymphoma returns after treatment, which is called relapsed disease.

HIV treatment

If CNS lymphoma is related to HIV infection, treatment of HIV with antiretroviral therapy is an important part of care. These medicines help strengthen the immune system and improve treatment outcomes.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.

Coping and support

Finding out you have central nervous system (CNS) lymphoma can be hard. Give yourself time to understand your condition and the treatments available. Ask your healthcare team any questions you have and make notes about important details.

Your family and friends can support you during treatment. Talking with others who have cancer also may bring comfort. Support groups let you share your experiences and learn from people facing similar challenges. Find support online through Mayo Clinic Connect, a community where you can connect with others for support, practical information and answers to everyday questions.

If you feel overwhelmed, talk with your care team. Your team can help you find counselors, social workers or other support.

Preparing for your appointment

If you notice symptoms that worry you, make an appointment with your regular healthcare professional. If your tests point to central nervous system (CNS) lymphoma, you might be sent to see a specialist, such as a neurologist or a hematologist.

Appointments can be brief, and there may be a lot of information to cover. Preparing ahead of time can help you make the most of your visit.

What you can do

  • List any symptoms you have, when they began and if they have changed over time.
  • Note any important personal details, such as major stresses, recent illnesses or changes in your health.
  • Make a list of all medicines you take, including prescription medicines, medicines you can buy without a prescription, vitamins and supplements, and the doses.
  • Bring any copies of your medical records, scans or test results if you have them.
  • Consider bringing a family member or friend. Someone who comes with you may help remember information.
  • Write down any questions you want to ask your healthcare professional.

Questions to ask may include:

  • What could be causing my symptoms?
  • What tests do I need?
  • Is my condition likely to be temporary or long term?
  • What treatment options are available?
  • What side effects might the treatment have?
  • What should I expect going forward?

What to expect from your doctor

Your healthcare professional likely will ask about your symptoms and health history, such as:

  • When did your symptoms begin?
  • Have your symptoms changed over time?
  • Do you have headaches, vision changes or issues with balance?
  • Have you had cancer or any concerns with your immune system?
  • What medicines do you take?

Your answers can help guide testing and treatment decisions.

April 01, 2026
  1. Shah T, et al. Central nervous system lymphoma. Seminars in Neurology. 2023; doi:10.1055/s-0043-1776783.
  2. Central nervous system (CNS) lymphoma. Blood Cancer United. https://bloodcancerunited.org/central-nervous-system-cns-lymphoma. Accessed Jan. 25, 2026.
  3. Central nervous system cancers. National Comprehensive Cancer Network. https://www.nccn.org/professionals/physician_gls/default.aspx. Accessed Jan. 25, 2026.
  4. Nayak L. Primary central nervous system lymphoma: Clinical features, diagnosis, and extent of disease evaluation. https://www.uptodate.com/contents/search. Accessed Jan. 25, 2026.
  5. Baehring JM. Secondary central nervous system lymphoma: Clinical features and diagnosis. https://www.uptodate.com/contents/search. Accessed Jan. 25, 2026.
  6. Hoffman R. Diffuse large B-cell lymphoma of the central nervous system. In: Hematology: Basic Principles and Practice. 8th ed. Elsevier; 2023. https://www.clinicalkey.com. Accessed Feb. 2, 2026.
  7. Ropper AH, et al. Intracranial neoplasms and paraneoplastic disorders. In: Adams and Victor's Principles of Neurology. 12th ed. McGraw Hill; 2023. https://accessmedicine.mhmedical.com. Accessed Feb. 2, 2026.
  8. AskMayoExpert. Primary central nervous system lymphoma: Diagnosis through treatment. Mayo Clinic; 2023.
  9. Cwynarski K. Management of secondary central nervous system lymphoma. British Journal for Haematology. 2023; doi:10.1111/bjh.18539.
  10. Primary central nervous system lymphoma. American Brain Tumor Association. https://www.abta.org/tumor_types/primary-central-nervous-system-lymphoma. Accessed Feb. 9, 2026.
  11. Kaplan LD, et al. HIV-related lymphomas: Primary central nervous system lymphoma. https://www.uptodate.com/contents/search. Accessed Feb. 9, 2026.
  12. Strowd RE. Approach to the patient with CNS lymphoma. In: Neuro-Oncology for the Clinical Neurologist. Elsevier; 2021. https://www.clinicalkey.com. Accessed Feb. 13, 2026.
  13. Rachdi A, et al. Recent advances in the diagnosis and the treatment of primary CNS lymphoma. Revue Neurologique. 2023; doi:10.1016/j.neurol.2023.03.012.
  14. Nayak L, et al. Primary central nervous system lymphoma: Treatment and prognosis. https://www.uptodate.com/contents/search. Accessed Feb. 13, 2026.
  15. Abramson JS. Secondary central nervous system lymphoma: Treatment and prognosis. https://www.uptodate.com/contents/search. Accessed Feb. 13, 2026.
  16. Questions to ask when you've been diagnosed with cancer. American Cancer Society. https://www.cancer.org/cancer/managing-cancer/making-treatment-decisions/questions-to-ask-your-doctor.html. Accessed Feb. 15, 2026.
  17. Communicating with your blood cancer specialist or care team. Blood Cancer United. https://bloodcancerunited.org/blood-cancer-care/adults/communicating-your-blood-cancer-specialist-care-team. Accessed Feb. 15, 2026.
  18. Ribas GA, et al. Primary central nervous system lymphoma: Imaging features and differential diagnosis. The Neuroradiology Journal. 2024; doi:10.1177/19714009241252625.
  19. Price M, et al. CBTRUS statistical report: Primary brain and other central nervous system tumors diagnosed in the United States in 2018–2022. Neuro-Oncology. 2025; doi:10.1093/neuonc/noaf194.
  20. Yescarta (approval letter). Biologic License Application 125643. U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/yescarta. Accessed March 5, 2026.
  21. Chimeric antigen receptor (CAR) T-cell therapy. Blood Cancer United. https://bloodcancerunited.org/blood-cancer-care/adults/types-blood-cancer-treatment/immunotherapy/chimeric-antigen-receptor-car-t-cell-therapy. Accessed March 8, 2026.
  22. Yescarta (prescribing information). Kite Pharma; 2026. https://www.yescarta.com. Accessed March 25, 2025.