Primary CNS Lymphoma: Diagnosis and Tests

This page is for people being tested for primary CNS lymphoma, a cancer of immune cells that starts in the brain, spinal cord, or eyes (the central nervous system, or CNS). It explains the tests, why timing of steroids matters, and what to ask.

Primary CNS lymphoma grows in the brain, spinal cord, or eyes. Symptoms often include headache, confusion, and seizures. Some people notice arm or leg weakness, double vision, hearing loss, or nausea and vomiting. NCI notes these symptoms can also be caused by other conditions, so tests are needed to tell the difference.

MRI of the brain is the key imaging test. It uses a contrast dye called gadolinium, which shows the tumor's location clearly. A lumbar puncture, also called a spinal tap, collects fluid from around the spinal cord to check for lymphoma cells. A stereotactic biopsy, which uses computer imaging to guide the needle, removes a small tissue sample for a definite diagnosis. Because this lymphoma can also affect the eyes, a dilated eye exam is one of the tests NCI lists. An HIV test is another, since HIV status affects the outlook and treatment options.

Steroids called glucocorticoids have an anticancer effect in lymphomas, according to NCI. If you have been given steroids, or are offered them, ask your team whether that matters for your testing and when the biopsy should happen. Tell the team right away if you have already started steroids elsewhere.

Many other brain tumors are treated by surgical removal. Primary CNS lymphoma is not. The biopsy is meant only to confirm the diagnosis, not to treat the disease. Treatment instead relies on chemotherapy, particularly high-dose methotrexate, sometimes combined with radiation.

Timing varies. Symptoms like confusion or vision changes can progress urgently. Ask your team directly how quickly a treatment plan can start, once the diagnosis is confirmed.

• Has a biopsy been done, or only imaging so far?
• Have I been given steroids, and does that matter for my testing?
• Were a lumbar puncture and eye exam done to check for spread?
• Was I tested for HIV, and how does that affect the treatment plan?
• How soon can treatment start once the diagnosis is confirmed?

• Call 911 or go to an emergency department if you have a seizure, or if weakness in an arm or leg, confusion, or slurred speech comes on over hours. Do not drive yourself.
• Call 911 or go to an emergency department if a severe headache comes with repeated vomiting, and you are getting drowsy, hard to wake, or losing vision. A tumor in the brain can raise the pressure inside the skull, and that pressure has to be brought down quickly. Do not drive yourself.
• Call your care team the same day if double vision, hearing loss, or a headache with mild nausea appears or clearly worsens while you are waiting for the biopsy or the results.
• Call your care team within a day or two if family or friends notice your thinking, memory, or personality drifting, even when you feel much the same. Changes like these often show from the outside first.

• National Cancer Institute — Primary CNS Lymphoma Treatment (PDQ).