Primary mediastinal large B-cell lymphoma (PMBCL)

Primary mediastinal large B-cell lymphoma is a type of non-Hodgkin lymphoma. Macmillan Cancer Support says it is sometimes called primary thymic mediastinal lymphoma. It develops when B-cells, white blood cells that normally help fight infection, become cancerous. The abnormal cells usually start in the thymus gland and then accumulate in lymph nodes behind the breastbone.

The mediastinum, which lies between the lungs, contains the gullet, windpipe, thymus, heart, large blood vessels and some lymph nodes. A growing lymphoma here can press on neighbouring structures. The NHS describes non-Hodgkin lymphoma more broadly as cancer that affects the white blood cells that help you fight infection, and PMBCL is one of several subtypes.

Macmillan says symptoms may be caused by the lymphoma pressing on structures in the chest. These include a cough, aching in the chest, breathlessness, a hoarse voice, swelling in the neck, arm or face, dizziness, and headaches that are worse when bending forward.

Some of these symptoms can be due to pressure on the superior vena cava, the large vein carrying blood from the upper body to the heart. Doctors call this superior vena cava obstruction. The NHS lists general symptoms of non-Hodgkin lymphoma as a painless lump in the neck, armpit or groin, a high temperature, night sweats, shortness of breath, itchy skin and sudden unexplained weight loss. Many of these have other causes, so they need checking rather than assuming the worst.

The NHS advises seeing a GP if you think you might have symptoms of non-Hodgkin lymphoma, because finding it early makes successful treatment more likely. A GP may feel for lumps, arrange blood tests and may make an urgent referral if symptoms could be cancer, which does not mean you definitely have cancer.

Swelling of the face, neck or arms together with breathlessness is a pattern that should not wait for a routine appointment. Contact NHS 111 for advice the same day, and call 999 or go to A&E if breathing becomes difficult or you feel faint or severely unwell. This is general safety advice rather than something taken from the pages read for this guide.

Macmillan says the most common test for diagnosing lymphoma is a biopsy, where a doctor takes a sample of tissue from the affected area. This is often an enlarged lymph node, which may be removed in whole or in part and sent to a laboratory. The NHS says needle biopsy or excision biopsy may be used, with a local or general anaesthetic, and results should usually be back within 2 weeks.

Once lymphoma is confirmed, the NHS says further tests may include blood tests, scans such as PET, CT, MRI or ultrasound, and sometimes a bone marrow biopsy. These show how far it has spread, which is called staging. Macmillan adds that doctors may use the term bulky disease for chest tumours 10cm (4 inches) across or bigger. Lymphomas are also graded, and PMBCL is high-grade.

A multidisciplinary team of specialists meets to discuss the best treatment. Macmillan says PMBCL is often treated with rituximab, an immunotherapy drug, combined with chemotherapy, called chemoimmunotherapy. Commonly used combinations include R-CHOP and DA-EPOCH-R. In DA-EPOCH-R the DA stands for dose-adjusted, which means doses can be changed depending on how the body responds. Steroids are often given alongside.

Some people have radiotherapy after chemoimmunotherapy to treat an area of lymphoma, which can also reduce the risk of it coming back in that area. Stem cell transplants are sometimes used if the lymphoma returns, and CAR-T cell therapy is sometimes used for relapsed PMBCL, although Macmillan says it is complicated, can have serious side effects and is only available in a few specialist hospitals. Some people take part in clinical trials.

Macmillan notes that some treatments for PMBCL can affect whether you can get pregnant or make someone pregnant, and advises talking with your doctor, cancer specialist or nurse before starting. The NHS gives the same advice for non-Hodgkin lymphoma, and says your specialist team will explain the benefits and side effects and help you manage them.

Treatment can be intensive, so planning for time off work, travel to appointments and support at home matters. The NHS says a clinical nurse specialist is usually your main point of contact during and after treatment. Macmillan and Lymphoma Action both offer support lines, forums and information, and Blood Cancer UK supports people with blood cancers.

Macmillan says PMBCL usually responds well to treatment, and the NHS says fast-growing non-Hodgkin lymphoma can often be completely cleared with treatment, although sometimes further treatment is needed. Because individual outlook depends on stage, how bulky the disease is and response, your own specialist is the right person to talk to about what to expect.

After treatment you will have regular check-ups, with appointments getting less frequent over time. Tell your team promptly about new symptoms between visits. Macmillan notes that some side effects can continue or appear months or years later, called late effects, and that healthy lifestyle changes may help recovery and long-term health. Feelings of relief mixed with worry about the future are common, and support is available.

In the UK, a GP refers suspected lymphoma to hospital haematology or oncology, often on an urgent suspected cancer pathway. Treatment is planned by a multidisciplinary team and given in specialist units. Biopsy, scans and blood tests are done through the same pathway.

Some people see a private haematologist for a second opinion or faster tests, and private cover can include chemotherapy. Treatment decisions for a fast-growing lymphoma should be made quickly by a specialist team with experience of lymphoma, whichever route you use. Ask for the name of your clinical nurse specialist and how to reach them.