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Primary mediastinal B-cell lymphoma


Primary mediastinal lymphoma


Primary mediastinal B-cell lymphoma is a subset of Diffuse Large B-cell lymphoma, which arises in the thymus, and presents as a mass in the mediastinum.

It primarily affects younger patients in their 30's and 40's, and is more common in women than men. It closely resembles Hodgkin's lymphoma, and has a similar prognosis to similarly staged DLBC.

PMBCL is an aggressive lymphoma which often presents with symptoms related to its location. Breathing problems, shortness of breath, pleural effusions, superior vena cava syndrome, fevers. etc. On initial diagnosis it is almost always limited to the mediastinal mass, but if a relapse occurs it is likely to occur in the kidneys, liver, central nervous system.

Diagnosis and Prognosis

PMBCL therapy and prognosis are the same for similarly staged patients with diffuse large b-cell lymphoma. The International Prognostic Index can assist with determining the overall prognosis.


Treatment consists of aggressive combination chemotherapy with the goal of curing the disease. In the event of a relapse a stem cell transplant is the preferred treatment option as is the case with other relapsed aggressive lymphomas.  Historically CHOP or MACOP would be used, but with the introduction of Rituxan MACOP may not be as popular. R-CHOP is one option but some evidence is showing that Dose Adjusted R-EPOCH may have better results. (1)

The role of radiotherapy is uncertain. It was commonly used and often considered necessary due to the size of the tumours and the location. However radiation to the mediastinum carries risks  to the heart, lungs and breast tissue. Here again, the addition of Rituxan to chemotherapy may eliminate the need for radiation due to the dramatic survival benefit Rituxan adds. (1) (2) (3) The choice of whether or not to use radiotherapy should be made in consultation with the doctor and after a review of the post chemotherapy CT and/or PET scans. 

Proton Beam Radiation instead of traditional radiation may be a better option. It appears deliver significantly less radiation to the major organs like the heart and lungs, when radiating a mediastinal mass. (4)

Additional topics

A highly detailed look at primary mediastinal lymphoma from The Oncologist Journal

Primary mediastinal lymphoma from e-medicine


  1. Primary mediastinal B-cell lymphoma and mediastinal gray zone lymphoma: do they require a unique therapeutic approach?

  2. Outcome of primary mediastinal large B-cell lymphoma (PMBCL) in the pre- and post-rituximab era: The Stanford University experience

  3. Role of radiation (RT) in primary mediastinal large B-cell lymphoma (PMBCL): An analysis of the Surveillance, Epidemiology, and End Results (SEER) database

  4. Rationale for and Preliminary Results of Proton Beam Therapy for Mediastinal Lymphoma.