Causes

In most instances, doctors don't know what causes non-Hodgkin's lymphoma. It begins when your body produces too many abnormal lymphocytes, which are a type of white blood cell.

Normally, lymphocytes go through a predictable life cycle. Old lymphocytes die, and your body creates new ones to replace them. In non-Hodgkin's lymphoma, your lymphocytes don't die, and your body keeps creating new ones. This oversupply of lymphocytes crowds into your lymph nodes, causing them to swell.

B cells and T cells

Non-Hodgkin's lymphoma most often begins in the:

• B cells. B cells are a type of lymphocyte that fights infection by producing antibodies to neutralize foreign invaders. Most non-Hodgkin's lymphoma arises from B cells. Subtypes of non-Hodgkin's lymphoma that involve B cells include diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma and Burkitt lymphoma.
• T cells. T cells are a type of lymphocyte that's involved in killing foreign invaders directly. Non-Hodgkin's lymphoma occurs much less often in T cells. Subtypes of non-Hodgkin's lymphoma that involve T cells include peripheral T-cell lymphoma and cutaneous T-cell lymphoma.

Whether your non-Hodgkin's lymphoma arises from your B cells or T cells helps to determine your treatment options.

Where non-Hodgkin's lymphoma occurs

Non-Hodgkin's lymphoma generally involves the presence of cancerous lymphocytes in your lymph nodes. But the disease can also spread to other parts of your lymphatic system. These include the lymphatic vessels, tonsils, adenoids, spleen, thymus and bone marrow. Occasionally, non-Hodgkin's lymphoma involves organs outside of your lymphatic system.