Primary mediastinal large B-cell lymphoma

Primary mediastinal large B-cell lymphoma (PMBCL) may also be called mediastinal B-cell lymphoma or mediastinal (thymic) large B-cell lymphoma. It is a fast-growing (aggressive) subtype of diffuse large B-cell lymphoma (DLBCL). It occurs in the thymus or in lymph nodes in the centre of the chest (called the mediastinum).

PMBCL is not common and occurs most often in people between the ages of 30 and 40. It is more common in women than in men.


People with PMBCL often have a large (bulky) mass in the chest. The mass can cause symptoms as it grows bigger, such as:

  • shortness of breath
  • cough
  • chest pain
  • a partial blockage of the main vein that carries blood from the upper body to the heart (called the superior vena cava), which can lead to superior vena cava syndrome

If PMBCL comes back (recurs) after treatment, it often comes back in organs or tissues outside the lymph nodes (called extranodal sites). These organs and tissues include the kidneys or brain and spinal cord (called the central nervous system, or CNS).


The following are treatment options for PMBCL.


Chemotherapy is often offered to treat PMBCL. A common combination of chemotherapy drugs used is CHOP:

  • cyclophosphamide (Cytoxan, Procytox)
  • doxorubicin (Adriamycin)
  • vincristine (Oncovin)
  • prednisone

When rituximab (Rituxan) is added to this combination, it is called R-CHOP.

Targeted therapy

Targeted therapy uses drugs to target specific molecules (such as proteins) on the surface of cancer cells. These molecules help send signals that tell cells to grow or divide. By targeting these molecules, the drugs stop the growth and spread of cancer cells while limiting harm to normal cells.

Rituximab (Rituxan) is a targeted therapy drug that can be used in combination with chemotherapy to treat PMBCL.

Radiation therapy

External beam radiation therapy directed at the mass in the chest is often given after chemotherapy.


Immunotherapy uses drugs to help the body’s immune system fight cancer cells.

Pembrolizumab (Keytruda) is an immune checkpoint inhibitor that may be used to treat primary mediastinal large B-cell lymphoma that is refractory (has not responded to treatment) or relapsed (has come back after treatment).

Axicabtagene ciloleucel (Yescarta) is a CAR T-cell therapy approved to treat people with primary mediastinal large B-cell lymphoma that has relapsed or is refractory after at least 2 other treatments.

Expert review and references

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