American Cancer Society Description of Primary Mediastinal B-Cell Lymphoma

This type accounts for about 2% of all lymphomas. The cells are large and resemble those of diffuse large B-cell lymphomas.

This lymphoma starts in the mediastinum (the area around the heart and behind the chest bone). It usually is localized at the beginning and rarely involves the bone marrow. It can cause trouble breathing because it often presses on the windpipe (trachea) leading into the lungs. It can also block the superior vena cava (the large vein that returns blood to the heart from the arms and head). This can cause the arms and face to swell.

About 2 out of 3 people with this lymphoma are women. Most are young -- in their 30s. It is a fast growing lymphoma but it is treatable. About half of patients can be cured.