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Approved by the Cancer.Net Editorial Board, 03/2022

About the lymphatic system

The lymphatic system is made up of lymph nodes, lymphatic organs, and lymphatic vessels. Its job is to fight infection and disease. The lymphatic system carries lymph, a colorless fluid that contains lymphocytes. Lymphocytes are a type of white blood cell that make up part of the immune system. Lymphatic vessels are thin tubes that branch out to all parts of the body.

There are several types of lymphocytes, including:

  • B cells, or B-lymphocytes, which make antibodies to fight bacteria and other infections.
  • T cells, or T-lymphocytes, which kill bacteria, viruses, fungi, and abnormal cells and trigger the B cells to make antibodies.

In a routine lab test called a complete blood count (CBC), lymphocytes are measured in the blood as part of the white blood cell count.

Groups of bean-shaped organs called lymph nodes are located throughout the body at different areas within the lymphatic system. The largest groups of lymph nodes are found in the chest, abdomen, groin, pelvis, underarms, and neck.

Other parts of the lymphatic system include the:

  • Spleen, which is located in the left upper abdomen, under the rib cage. The spleen makes lymphocytes and filters the blood.
  • Thymus, which is an organ located behind the breastbone. The thymus plays an important role in the development of T cells.
  • Tonsils, which are located in the throat. The tonsils help trap bacteria entering through the mouth or nose.

About Hodgkin lymphoma

Lymphoma is a cancer of the lymphatic system. Hodgkin lymphoma, which used to be called Hodgkin’s disease, is one of many types of lymphoma. Lymphoma begins when healthy cells in the lymphatic system change and grow out of control. This uncontrolled growth may form a tumor, involve many parts of the lymphatic system, or spread to other parts of the body.

Hodgkin lymphoma most commonly affects lymph nodes in the neck or in the area between the lungs and behind the breastbone, which is called the mediastinum. It can also begin in groups of lymph nodes under an arm, in the groin, or in the abdomen or pelvis.

If Hodgkin lymphoma spreads to areas that are not lymph nodes, the most common locations include the lung, spleen, liver, bone marrow, or bone. Hodgkin lymphoma can spread to other parts of the body, but this is unusual.

This section covers Hodgkin lymphoma in adults. Learn more about childhood Hodgkin lymphoma or non-Hodgkin lymphoma in adults in other guides on this website.

Types of Hodgkin lymphoma

There are different types of Hodgkin lymphoma. It is important to know the type because this may affect how the cancer is treated. Doctors determine the type of Hodgkin lymphoma based on how the cells look under a microscope and whether the cells contain certain abnormal proteins. These cells are taken using a tissue biopsy (see Diagnosis).

The American Joint Committee on Cancer (AJCC) recognizes 2 major categories of Hodgkin lymphoma: classic Hodgkin lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma.

Classical Hodgkin lymphoma (cHL)

cHL is the most common type of Hodgkin lymphoma. About 95% of cases of Hodgkin lymphoma are within the cHL category. cHL is diagnosed when certain abnormal lymphocytes, known as Reed-Sternberg cells, are found. cHL is divided into 4 subtypes, based on the appearance of the lymph node structure and cells:

  • Nodular sclerosis Hodgkin lymphoma. Nodular sclerosis Hodgkin lymphoma is the most common subtype of cHL. It affects up to 80% of people diagnosed with cHL. Nodular sclerosis Hodgkin lymphoma is most common in young adults, especially women. In addition to Reed-Sternberg cells, there are bands of connective tissue (called fibrosis) found in the lymph node. The presence of these bands can help diagnose this type of Hodgkin lymphoma. This type of lymphoma often affects the lymph nodes in the central part of the chest, called the mediastinum.
  • Mixed cellularity Hodgkin lymphoma. This subtype of cHL occurs most often in older adults. It sometimes develops in the abdomen and carries many different cell types, including large numbers of Reed-Sternberg cells.
  • Lymphocyte-rich cHL. About 6% of people with cHL are diagnosed with lymphocyte-rich cHL. It is more common in men and usually affects areas other than the mediastinum. In addition to Reed-Sternberg cells, the lymph node tissue contains many normal lymphocytes.
  • Lymphocyte-depleted Hodgkin lymphoma. Lymphocyte-depleted Hodgkin lymphoma is the least common subtype of cHL. Only about 1% of people with cHL have this subtype. It is most common in older adults; people with the human immunodeficiency virus (HIV), the virus that causes autoimmune deficiency syndrome (AIDS); and people in non-industrialized countries. The lymph node contains almost all Reed-Sternberg cells.

Nodular lymphocyte-predominant Hodgkin lymphoma

About 5% of people with Hodgkin lymphoma have nodular lymphocyte-predominant Hodgkin lymphoma. It often develops in the lymph nodes in the neck, groin, or armpit. It is most common in younger people.

Nodular lymphocyte-predominant Hodgkin lymphoma is more similar to B-cell non-Hodgkin lymphoma. People with this type of Hodgkin lymphoma have large cells in the affected area called “popcorn cells” or “LP cells” that have a marker called CD20 on their surface. CD20 is a protein that is usually found in people diagnosed with B-cell non-Hodgkin lymphoma.

Nodular lymphocyte-predominant Hodgkin lymphoma is often treated differently from cHL. Some people with nodular lymphocyte-predominant Hodgkin lymphoma do not need treatment right away, while others may benefit from a treatment plan that includes radiation therapy, chemotherapy, or a monoclonal antibody called rituximab (Rituxan). This is explained further in Types of Treatment.

People with nodular lymphocyte-predominant Hodgkin lymphoma tend to have a very good prognosis. This means the treatment, if needed, has a very good chance of being successful and helps the patient recover. However, a small number of people with nodular lymphocyte-predominant Hodgkin lymphoma may develop a more aggressive type of non-Hodgkin lymphoma called diffuse large B-cell lymphoma through a process called transformation.