Primary CNS lymphoma
A primary CNS lymphoma is a type of lymphoma (cancerous tumour of the lymph cells) that starts in the central nervous system (CNS).
This information describes primary CNS lymphomas, their symptoms, tests, and possible treatments. It should ideally be read with our general information about brain tumours.
We hope this information answers your questions. If you have any further questions, you can ask your doctor or nurse at the hospital where you are having treatment.
The central nervous system (CNS) is made up of the brain and spinal cord. A lymphoma is a cancerous tumour of the lymph cells, which are part of the body’s immune system and help fight infection.
Lymphomas that start in the CNS are called primary CNS lymphomas. Most of those affecting the brain are high grade non-Hodgkin lymphomas.
Some lymphomas in the head will have spread from lymphomas in other parts of the body (secondary lymphoma). It’s important to know if a lymphoma in the brain is a primary or secondary because they are treated differently.
The most common site for a primary CNS lymphoma is the cerebrum (see the diagram below). Sometimes more than one tumour is present. Less commonly, other parts of the CNS can be the primary site, including the lining of the brain (meninges), the eyes or the spinal cord.
Causes of primary CNS lymphoma
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Usually the cause is not known and research is being carried out to look into possible causes. Most people who develop this type of cancer have a normal immune system. However, primary CNS lymphoma may affect people whose immune system is not working properly – for example, after organ transplants or in people with HIV.
Tumours affecting the CNS are fairly rare. Each year about 9,000 people in the UK are diagnosed with tumours of the CNS. Around 1 in 25 (4%) of these are primary CNS lymphomas.
Raised intracranial pressure
The main symptoms arise from increased pressure within the skull, which is known as raised intracranial pressure. The pressure can increase because of a blockage in the ventricles (fluid-filled spaces in the brain), which leads to a build-up of cerebral spinal fluid (CSF). CSF is the fluid that surrounds and protects the brain and spinal cord. The increased pressure may also be caused by the tumour itself.
Raised intracranial pressure can cause headaches, sickness (vomiting) and problems with vision.
Seizures can occur with this type of tumour and the person may appear to be confused at times. Changes in behaviour and personality may also occur.
Changes in balance/movement
A tumour in the cerebrum may cause a weakness on one side of the body (hemiparesis). If the area known as the cerebellum is affected, there may be signs of loss of coordination and balance. People with a tumour in this part of the brain may walk awkwardly or stumble. They can also have trouble keeping their balance.
Tests and investigations
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Your doctors need to find out as much as possible about the type, position and size of the tumour so they can plan your treatment. You may have a number of tests and investigations.
The doctor will examine you thoroughly and test your reflexes and the power and feeling in your arms and legs.
Your doctor will look into the back of your eyes using an ophthalmoscope to see if the nerve at the back of the eye is swollen. This can be caused by oedema (swelling of the tissues within the brain), which may occur due to an increase in the amount of fluid in the brain.
You will have a CT or MRI scan to find out the exact position and size of the tumour.
CT (computerised tomography) scan
A CT scan takes a series of x-rays that build up a three-dimensional picture of the inside of the body. The scan is painless but takes 10–30 minutes. CT scans use small amounts of radiation, which will be very unlikely to harm you or anyone you come into contact with.
You may be given an injection of a dye, which allows particular areas to be seen more clearly. This may make you feel hot all over for a few minutes. If you’re allergic to iodine or have asthma you could have a more serious reaction to the injection, so it’s important to let your doctor know beforehand.
MRI (magnetic resonance imaging) scan
This test is similar to a CT scan but uses magnetism instead of x-rays to build up a detailed picture of areas of your body. Before the scan you may be asked to complete and sign a checklist. This is to make sure it’s safe for you to have an MRI scan.
Before having the scan, you’ll be asked to remove any metal belongings including jewellery. Some people are given an injection of dye into a vein in the arm. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test you will be asked to lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It’s painless but can be slightly uncomfortable, and some people feel a bit claustrophobic during the scan. It’s also noisy, but you’ll be given earplugs or headphones.
A lumbar puncture is carried out to see if there are any tumour cells present in the cerebrospinal fluid (CSF). CSF is the fluid that surrounds and protects the brain and spinal cord.
The skin on your back is numbed with local anaesthetic and a hollow needle is inserted between two of the spinal bones and into the spinal canal. A small amount of spinal fluid is withdrawn for tests.
To give an exact diagnosis, a sample of cells from the tumour (biopsy) is sometimes taken, then looked at under a microscope. The biopsy involves an operation. Your doctor will discuss whether this is necessary in your case and explain exactly what the operation will involve.
The treatment for a primary CNS lymphoma depends on a number of things including your general health, the size and position of the tumour, and whether or not it has spread. The results of your tests will enable your doctor to decide on the best type of treatment for you.
Your treatment will usually be planned by a team of specialists known as a multidisciplinary team (MDT). The team will usually include:
a doctor who specialises in treating cancer (an oncologist)
a doctor who specialises in treating illnesses of the brain and nervous system (a neurologist)
a specialist nurse
and other healthcare professionals, such as a physiotherapist or dietitian.
Before you have any treatment, your doctor will tell you about its aims and what it involves. They will also discuss any significant risks or side effects. They will usually ask you to sign a form saying that you give your permission (consent) for the hospital staff to give you the treatment. No medical treatment can be given without your consent.
Benefits and disadvantages of treatment
Treatment can be given for different reasons and the potential benefits will vary for each person. If you have been offered treatment that aims to cure your cancer, deciding whether to have the treatment may not be difficult. However, if a cure is not possible and the treatment is to control the cancer for a period of time, it may be more difficult to decide whether to go ahead.
If you feel that you can’t make a decision about the treatment when it’s first explained to you, you can always ask for more time to decide.
You are free to choose not to have the treatment and the staff can explain what may happen if you don't have it. Although you don’t have to give a reason for not wanting to have treatment, it can be helpful to let the staff know your concerns so that they can give you the best advice.
If you have raised intracranial pressure it’s important to reduce it before any treatment is given for the lymphoma. Steroid drugs are used to reduce swelling around the tumour, and may shrink the tumour itself.
Chemotherapy is the use of anti cancer (cytotoxic) drugs to destroy cancer cells. Chemotherapy is often used as part of the treatment for primary CNS lymphoma. It is usually given into a vein (intravenously). It can also be given into the fluid surrounding the brain by a lumbar puncture, or through a special flat plastic bubble (ommaya reservoir), which is inserted under the scalp during an operation. A number of research trials are being carried out to improve this type of treatment.
The most common chemotherapy drug used is methotrexate, which is given in high doses. It can be given on its own or in combination with other chemotherapy drugs and/or steroids.
Radiotherapy treatment uses high‑energy rays to destroy the cancer cells and is an effective treatment for primary CNS lymphoma. It may be used alone, in combination with steroids or after chemotherapy treatment.
Surgery is rarely used to treat primary CNS lymphoma. This is because there are often several tumours or the tumour is deep in the brain.
Medicines for seizures
If you experience a seizure, you may be given a medicine called an anticonvulsant to help prevent them.
You may find the idea of a tumour affecting the brain extremely frightening. You may experience many emotions, including anxiety, anger and fear. These are all normal reactions and are part of the process many people go through in trying to come to terms with their condition.
Many people find it helpful to talk things over with their doctor or nurse, or with one of our cancer support specialists. Close friends and family members can also offer support.
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In some circumstances, you may not be allowed to drive for a period of time. If you have had an epileptic fit, the Drivers and Vehicle Licensing Association (DVLA) will not allow you to drive for a year after your last fit. You can then drive again, provided you remain well.
After surgery to the cerebrum (the main part of the brain), there is a small risk that you will have epileptic fits and the DVLA requires that you do not drive for a year after this type of surgery.
You may not be allowed to drive some types of vehicle, such as an LGV (large goods vehicle) or a PCV (passenger carrying vehicle).
It is your responsibility to contact the DVLA and your doctor will advise you how to do this.
Drivers and Vehicle Licensing Association (DVLA)
The DVLA advises GPs and other members of the medical profession on the medical standards of fitness to drive. Patients should seek advice from their doctors.
This information has been compiled using a number of reliable sources, including:
Bernstein & Berger. Neuro-oncology – the essentials. 2nd edition. 2008. Thieme.
Souhami & Hochhaser. Cancer and its management. 6th edition. 2010. Wiley-Blackwell.
Hockburg et al. Clinical presentation, pathologic features, and diagnosis of primary central nervous system lymphoma. 2012. http://www.uptodate.com (accessed September 2012).
Hockburg & Batchelor. Treatment and prognosis of primary central nervous system lymphoma. 2012. http://www.uptodate.com (accessed September 2012).
Ferreri A J. How I treat primary CNS lymphoma. Blood. 2011. 118:510–522.
Cancer Stats. Key facts: Brain and other central nervous system (CNS) tumours. September 2012. Cancer Research UK.
With thanks to Dr Nick Plowman, Consultant Clinical Oncologist, and the people affected by cancer who reviewed this edition. Reviewing information is just one way you could help when you join our Cancer Voices network.