Primary mediastinal large B-cell lymphoma

Primary mediastinal large B-cell lymphoma (PMBCL) is a rare type of non-Hodgkin lymphoma (NHL). It mainly affects young adults, and is more common in women.

PMBCL develops when the body makes abnormal B-cells – the lymphoma cells. B-cells are white blood cells that fight infection. The lymphoma cells build up between the lungs and behind the breast bone, in an area called the mediastinum. This may cause symptoms including:

  • a cough
  • aching in the chest
  • breathlessness
  • hoarseness
  • swelling in the neck, arm and face.

To diagnose PMBCL, a doctor removes some tissue from the area and checks it for lymphoma cells. You will also have tests and scans to find out whether the lymphoma has spread. This is called staging

PMBCL is fast-growing and needs to be treated quickly. This is usually with a combination of chemotherapy drugs and a targeted therapy drug called rituximab. Some people may also have radiotherapy. You may be invited to join a clinical trial looking at new ways of treating PMBCL. You can talk about this with your lymphoma doctor.

What is primary mediastinal large B-cell lymphoma (PMBCL)?

It is best to read this information with our general information about non-Hodgkin lymphoma (NHL). If you have any more questions, you can ask your doctor or nurse at the hospital where you are having treatment.

Primary mediastinal large B-cell lymphoma (PMBCL) is a fast-growing type of NHL. It is also sometimes called primary thymic mediastinal lymphoma. It develops when the body makes abnormal B-cells (also called B-lymphocytes). B-cells are white blood cells that fight infection.

The abnormal B-cells (lymphoma cells) develop in a part of the lymphatic system called the thymus gland. They then build up in lymph nodes in the space behind the breast bone and between the lungs. This area is called the mediastinum. It contains:

  • the gullet
  • the windpipe
  • the thymus
  • the heart
  • some large blood vessels
  • some lymph nodes.

The lymphatic system
The lymphatic system

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Causes and risk factors for PMBCL

The causes of PMBCL are not known. It mainly occurs in people aged 25 to 40, and is more common in women. Like other cancers, it is not infectious and cannot be passed on to other people.

We have more information about risk factors for lymphoma.


Signs and symptoms of PMBCL

Symptoms may be caused by the lymphoma pressing on structures in the chest. This can cause:

  • a cough
  • aching in the chest
  • breathlessness
  • a hoarse voice
  • swelling in the neck, arm or face
  • dizziness
  • headaches that are worse when bending forward.

Some of these symptoms can be caused by lymphoma pressing on a large vein in the chest, called the superior vena cava (SVC). This vein carries all the blood from the upper half of the body to the heart. If pressure on the SVC blocks the blood from flowing along it, doctors call this superior vena cava obstruction (SVCO).

B symptoms

Some people also have:

  • drenching night sweats
  • high temperatures (fevers) with no obvious cause
  • unexplained weight loss.

These are called B symptoms.


Diagnosing PMBCL

To diagnose PMBCL, a doctor removes samples of tissue from the tumour (biopsies). These are sent to a laboratory for testing.

You can usually have this test as a day patient. It may be done under local or general anaesthetic. The doctor makes a small cut in the skin at the base of the neck. They can then use special instruments to take samples from the area.

You may have some other tests, such as:

  • blood tests
  • x-rays
  • a CT scan
  • a PET scan.

Doctors use the information from all these tests to find out more about the lymphoma, such as its stage and grade.


Staging and grading of PMBCL

Staging

The stage of the lymphoma describes which areas of the body are affected by lymphoma. This information helps doctors plan the right treatment for you.

The stage of a lymphoma is usually described using numbers from 1 to 4. Stages 1 and 2 are also called early-stage, limited or localised lymphoma. Stages 3 and 4 are also called advanced lymphoma.

PMBCL is usually diagnosed at an early stage.

As well as giving each stage a number, doctors also add the letters A or B. A means you do not have B symptoms. B means you do have B symptoms.

Doctors may use the term bulky disease to describe tumours in the chest that are 10cm (4 inches) across or bigger.

Grading

Non-Hodgkin lymphomas are divided into two groups:

  • Low-grade (indolent) lymphomas usually grow slowly.
  • High-grade (aggressive) lymphomas grow more quickly.

PMBCL is a high-grade lymphoma.


Treating PMBCL

PMBCL is fast-growing and needs to be treated quickly. The aim of treatment is to get rid of all signs of the lymphoma and hopefully to cure you. Treatments for PMBCL may affect fertility. If you may want to get pregnant or father a child in the future, it is important to talk to your doctor about this.

The main treatment for PMBCL is chemotherapy combined with a targeted therapy called rituximab. You may also be offered radiotherapy after chemotherapy.

PMBCL usually responds well to treatment. But if it does not respond or if the lymphoma comes back, you will need more treatment. This may include a stem cell transplant.

Rituximab

The drug rituximab is often used with chemotherapy to treat this type of lymphoma. It works by targeting proteins on the surface of B-cell lymphocytes. This makes the body destroy these cells.

Rituximab is given as a drip into a vein or an injection under the skin.

Chemotherapy

Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells.

You will have a combination of different chemotherapy drugs given into a vein (intravenously), either as injections or through a drip (infusion). Your specialist will explain which combination of drugs is most appropriate for you.

Commonly used treatments include:

  • R-CHOP – this is made up of rituximab, the chemotherapy drugs cyclophosphamide, doxorubicin (also called hydroxydaunomycin) and vincristine (also called Oncovin®), and prednisolone (a steroid).
  • DA-EPOCH-R – this is made up of the chemotherapy drug etoposide, prednisolone, the chemotherapy drugs vincristine (Oncovin), cyclophosphamide and doxorubicin (hydroxydaunomycin), and rituximab. ‘DA’ stands for ‘dose-adjusted’, as the dose of drugs can be adjusted depending on how your body responds to the treatment.

Steroids

Steroids are drugs that are often given with chemotherapy to treat lymphomas. They help make chemotherapy more effective. They also help you feel better and can reduce feelings of sickness.

Radiotherapy

Radiotherapy uses high-energy rays to destroy cancer cells, while doing as little harm as possible to the healthy cells.

Radiotherapy may be given after chemotherapy and rituximab. It is given to the area where the lymphoma was. The aim is to reduce the risk of the lymphoma coming back. In some people, radiotherapy can have long-term effects. Your doctor can talk with you about the possible benefits and risks of radiotherapy in your case.

Stem cell treatment (transplants)

This treatment may be used to treat PMBCL that doesn’t respond completely to chemotherapy and rituximab. It may also be used if the lymphoma comes back after treatment. It is an intensive treatment, so it is not suitable for everyone.

Stem cells are a type of blood cell that can make all other types of blood cells.

There are different types of stem cell treatment:

High-dose treatment with stem cell support (autologous stem cell transplant)

Some people have treatment to put the lymphoma into remission. Then some of their own stem cells are collected from their blood and stored. Then they have high doses of chemotherapy to try to destroy any remaining lymphoma cells. After this, their stem cells are returned through a drip (like a blood transfusion). The stem cells help their blood cell numbers recover from the effects of chemotherapy.

Donor transplant (allogeneic transplant)

Some people have chemotherapy to put the lymphoma into remission and are then given stem cells from another person (a donor).


Clinical trials

Your lymphoma doctor may talk to you about having treatment as part of a clinical trial. Clinical trials test new treatments or new ways of giving treatments.


Follow-up after treatment

After treatment, you will have regular check-ups. These appointments are a good opportunity for you to talk to your doctor or nurse about any concerns you have. Your doctor will want to know how you are feeling generally, and to check you are recovering from any side effects of treatment. We have more information about follow-up.


Getting support

Everyone has their own way of dealing with illness and the different emotions they experience. You may find it helpful to talk things over with family and friends or your doctor or nurse. You can also call our cancer support specialists free on 0808 808 00 00. The organisations below also offer information and support:

  • Bloodwise offers support and information to people affected by blood cancers, including lymphoma.
  • The Lymphoma Association gives emotional support, advice and information on all aspects of Hodgkin lymphoma and non-Hodgkin lymphoma. It has a national network of people with lymphoma, and local groups.