What Is Non-Hodgkin Lymphoma?

Cancer starts when cells in the body begin to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other areas of the body. To learn more about how cancers start and spread, see What Is Cancer?

Non-Hodgkin lymphoma (also known as non-Hodgkin’s lymphoma, NHL, or sometimes just lymphoma) is a cancer that starts in white blood cells called lymphocytes, which are part of the body’s immune system.

There are two types of lymphoma. They are treated differently, so it’s important to know which one you have. The information here focuses on non-Hodgkin lymphoma in adults.

For information on the other type of lymphoma, seeHodgkin Lymphoma. We also have separate information aboutnon-Hodgkin lymphoma in children and lymphoma of the skin.

The lymph system

To understand what lymphoma is, it helps to know about the body’s lymph system (also known as the lymphatic system). The lymph system is part of the immune system, which helps fight infections and some other diseases. The lymph system also helps fluids move through the body.

Lymphocytes

The lymph system is made up mainly of immune system cells that help the body fight infections. Most of these cells are lymphocytes, a type of white blood cell. There are 2 main types of lymphocytes:

B lymphocytes (B cells):B cells normally help protect the body against germs (bacteria or viruses) by making proteins called antibodies. The antibodies attach to the germs, marking them for destruction by other parts of the immune system.

T lymphocytes (T cells):There are several types of T cells. Some T cells destroy germs or abnormal cells in the body. Other T cells help boost or slow the activity of other immune system cells.

Non-Hodgkin lymphoma can develop from either type of lymphocyte, but B-cell lymphomas are much more common in the United States than T-cell lymphomas. Different types of lymphoma can develop from each type of lymphocyte, based on how mature the cells are when they become cancerous and other factors.

Treatment for non-Hodgkin lymphoma depends on which type it is, so it’s important for doctors to find out theexact type of lymphomayou have.

How non-Hodgkin lymphoma starts and spreads

Lymph tissue is found in many places throughout the body, so lymphomas can start almost anywhere.

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The major sites of lymph tissue are:

  • Lymph nodes: Lymph nodes are bean-sized collections of lymphocytes and other immune system cells throughout the body, including inside the chest, abdomen, and pelvis. They are connected by a system of lymphatic vessels.
  • Spleen: The spleen is an organ under the lower ribs on the left side of the body. The spleen makes lymphocytes and other immune system cells. It also stores healthy blood cells and filters out damaged blood cells, bacteria, and cell waste.
  • Bone marrow: The bone marrow is the spongy tissue inside certain bones. This is where new blood cells (including some lymphocytes) are made.
  • Thymus: The thymus is a small organ behind the upper part of the breastbone and in front of the heart. It’s important in the development of T lymphocytes.
  • Adenoids and tonsils: These are collections of lymph tissue in the back of the throat. They help make antibodies against germs that are breathed in or swallowed.
  • Digestive tract: The stomach, intestines, and many other organs also have lymph tissue.

There are many different types of non-Hodgkin lymphoma, which can start in different parts of the body. This can affect which symptoms a person has.

Non-Hodgkin lymphoma can also grow and spread at different rates, depending on which type it is:

  • Some types of lymphoma tend to grow and spread slowly. These are known as indolent lymphomas. Some indolent lymphomas might not need to be treated right away, but can be watched closely instead. The most common type of indolent lymphoma in the United States is follicular lymphoma.
  • Some types of lymphoma tend to grow and spread quickly. These are known as aggressive lymphomas, and they usually need to be treated right away. The most common type of aggressive lymphoma in the United States is diffuse large B cell lymphoma (DLBCL).
  • Some types of lymphoma don’t fit neatly into either of these categories.

Regardless of how quickly they grow, all non-Hodgkin lymphomas can to spread to other parts of the lymph system if not treated. Eventually, they can also spread to other parts of the body, such as the liver, brain, or bone marrow.