What is non-Hodgkin lymphoma?

Non-Hodgkin lymphoma (also known as non-Hodgkin's lymphoma, NHL, or sometimes just lymphoma) is a cancer that starts in cells called lymphocytes, which are part of the body's immune system. Lymphocytes are in the lymph nodes and other lymphoid tissues (such as the spleen and bone marrow). These will be described in more detail below.

Some other types of cancer – lung or colon cancers, for example – can spread to lymph tissue such as the lymph nodes. But cancers that start in these places and then spread to the lymph tissue are not lymphomas.

There are 2 main types of lymphomas.

    Hodgkin lymphoma (also known as Hodgkin's lymphoma, Hodgkin disease, or Hodgkin's disease), which is named after Dr. Thomas Hodgkin, who first described it
    Non-Hodgkin lymphoma

These 2 types of lymphomas behave, spread, and respond to treatment differently.

Doctors can usually tell the difference between them by looking at the cancer cells under a microscope. In some cases, sensitive lab tests may be needed to tell them apart.

Hodgkin disease is discussed in a separate American Cancer Society document. We also have other documents that focus on non-Hodgkin lymphoma in children and lymphoma of the skin.

The rest of this document focuses only on non-Hodgkin lymphoma in adults.
The lymph system and lymphoid tissue

To know what lymphoma is, it helps to understand the body's lymph system.

The lymph system (also known as the lymphatic system) is composed mainly of lymphoid tissue, lymph vessels, and a clear fluid called lymph. Lymphoid tissue includes the lymph nodes and related organs that are part of the body's immune and blood-forming systems, such as the spleen and bone marrow.
Lymphocytes

Lymphoid tissue is made up of several types of immune system cells that help the body fight infections. Most of the cells in lymphoid tissue are lymphocytes, a type of white blood cell. The 2 main types of lymphocytes are B lymphocytes (B cells) and T lymphocytes (T cells). Normal B cells and T cells do different jobs within the immune system.

B lymphocytes: 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 immune system cells. Antibodies also attract certain blood proteins that can kill bacteria.

T lymphocytes: There are several types of T cells, each with a special job. Some T cells can directly destroy cells infected with viruses, fungi, or certain kinds of bacteria. T cells can also release substances that attract other types of white blood cells, which then digest the infected cells. Some types of T cells play a role in either boosting or slowing the activity of other immune system cells.

Both types of lymphocytes can develop into lymphoma cells, 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 each lymphoma depends on which type it is, so determining the exact type of lymphoma is important.
Organs that have lymphoid tissue


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