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

Primary mediastinal large B-cell lymphoma (PMBCL) is a fast-growing type of non-Hodgkin lymphoma (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.


Symptoms of primary mediastinal large B-cell lymphoma (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

Doctors call this group of symptoms B symptoms.

Causes of primary mediastinal large B-cell lymphoma (PMBCL)

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

We have more information about causes and risk factors for non-Hodgkin lymphoma (NHL).

Diagnosis of primary mediastinal large B-cell lymphoma (PMBCL)

Biopsy for lymphoma

The most common test for this lymphoma is to remove part or all of an enlarged lymph node (a biopsy). This may be done under local or general anaesthetic. The biopsy is then sent to a laboratory to be checked for lymphoma cells. You may also have biopsies taken from other areas of the body.

You can read more about further tests you may have in our information about non-Hodgkin lymphoma.

Waiting for test results can be a difficult time. It may help to talk to your family, friends or specialist nurse.

Staging and grading of primary mediastinal large B-cell lymphoma (PMBCL)

The results of your tests help your doctors find out how many areas of the body are affected by lymphoma and where these areas are. This is called staging. Doctors may use the term bulky disease to describe tumours in the chest that are 10cm (4 inches) across or bigger.

Lymphomas are also grouped as either low-grade or high-grade. Low-grade lymphomas are usually slow growing and high-grade lymphomas grow more quickly. PMBCL is a high-grade lymphoma and is usually diagnosed at an early stage.

We have more information about staging and grading of non-Hodgkin lymphoma.

Treatment for primary mediastinal large B-cell lymphoma (PMBCL)

A team of specialists will meet to discuss the best possible treatment for you. This is called a multidisciplinary team (MDT).

Your doctor or cancer specialist or nurse will explain the different treatments and their side effects. They will also talk to you about things to consider when making treatment decisions.

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.

Some treatments for PMBCL can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor or nurse before you start treatment.

Treatments for PMBCL may include the following:

  • Targeted therapy

    The targeted therapy drug called rituximab is often used with chemotherapy to treat PMBCL.

  • Chemotherapy

    The main treatment for PMBCL is chemotherapy combined with a targeted therapy called rituximab.

    Commonly used treatments include:

    • R-CHOP
    • 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.

  • Radiotherapy

    Radiotherapy uses high-energy rays to destroy cancer cells, while doing as little harm as possible to normal cells. Some people have radiotherapy after chemotherapy and rituximab to treat an area of lymphoma. It can also reduce the risk of lymphoma coming back in that area.

  • Stem cell transplants

    Stem cell transplants are sometimes used to treat lymphoma that has come back after treatment. Stem cell transplants are intensive treatments, so they are not suitable for everyone. You may have a transplant using your own stem cells autologous stem cell transplant or cells from a donor allogeneic stem cell transplant.

You may have some treatments as part of a clinical trial.

PMBCL usually responds well to treatment. But if it does not respond or if the lymphoma comes back, you will need more treatment.

We have more information about treating lymphoma that has come back.

After primary mediastinal large B-cell lymphoma (PMBCL)

You have regular follow-up appointments after treatment. 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.

Well-being and recovery

Even if you already have a healthy lifestyle, you may choose to make some positive lifestyle changes after treatment.

Making small changes such as eating well and keeping active can improve your health and wellbeing and help your body recover.

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.

Macmillan is also here to support you. If you would like to talk, you can:

The organisations below also offer information and support:

  • Blood Cancer UK

    Blood Cancer UK is a blood cancer research charity that provides information and support on any type of blood cancer.

  • Lymphoma Action

    Lymphoma Action 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.

About our information

  • References

    Below is a sample of the sources used in our primary mediastinal large B-cell lymphoma (PMBCL) information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    Vitolo U, Seymour JF, et al. Extranodal diffuse large B-cell lymphoma and primary mediastinal B-cell lymphoma: ESMO Clinical Practice Guidelines. Annals of Oncology. 2016. 27 (Supplement 5), v91-v102. Available from: www.annalsofoncology.org/article/S0923-7534(19)31640-0/pdf

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Professor Rajnish Gupta, Macmillan Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

Reviewed: 31 January 2018
Reviewed: 31/01/2018
Next review: 31 January 2012
Next review: 31/01/2012