About the lymphatic system
The lymphatic system is made up of thin tubes that branch out to all parts of the body. 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 and help fight germs in the body.
There are several types of lymphocytes, including:
B-lymphocytes, or B cells, that make antibodies to fight bacteria and other infections
T-lymphocytes, or T cells, that kill viruses and foreign cells and trigger the B cells to make antibodies.
Groups of bean-shaped organs called lymph nodes are located throughout the body at different areas in the lymphatic system. The largest groups of lymph nodes are found in the abdomen, groin, pelvis, underarms, and neck.
Other parts of the lymphatic system include the:
Spleen, which makes lymphocytes and filters the blood
Thymus, which is an organ located behind the breastbone
Tonsils, which are located in the throat.
About Hodgkin lymphoma
Hodgkin lymphoma, which used to be called Hodgkin’s disease, is one of many types of cancer that develops in the lymphatic system. Lymphoma begins when healthy cells in the lymphatic system change and grow uncontrollably. 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 the area between the lungs and behind the breastbone. 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, it may spread to the spleen, liver, bone marrow, or bone. Hodgkin lymphoma can spread to other parts of the body, but this is unusual.
Types of Hodgkin lymphoma
There are different types of Hodgkin lymphoma. It is important to know the type, as this may affect how the cancer is treated. Doctors determine the type of Hodgkin lymphoma based on how the cells in a tissue biopsy (see the Diagnosis section) look under a microscope and whether the cells contain certain abnormal proteins.
The American Joint Committee on Cancer (AJCC) recognizes 2 major categories of Hodgkin lymphoma: classical Hodgkin lymphoma, which is divided into 4 subtypes based on the appearance of the cells, and nodular lymphocyte-predominant Hodgkin lymphoma.
Classical Hodgkin lymphoma (cHL)
cHL is the most common type of Hodgkin lymphoma. It occurs about 95% of the time. cHL is diagnosed when characteristic abnormal lymphocytes, known as Reed-Sternberg cells, are found. cHL is divided into 4 different subtypes:
Nodular sclerosis Hodgkin lymphoma. Nodular sclerosis Hodgkin lymphoma is the most common type 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 found in the lymph node. This type of lymphoma often affects the lymph nodes in the central part of the chest called the mediastinum.
Lymphocyte-rich classical Hodgkin lymphoma. About 6% of people with cHL are diagnosed with lymphocyte-rich classical Hodgkin lymphoma. It is more common in men and usually affects areas other than the mediastinum. The lymph node tissue contains many normal lymphocytes, in addition to Reed-Sternberg cells.
Mixed cellularity Hodgkin lymphoma. This subtype of lymphoma occurs in older adults. It commonly develops in the abdomen and carries many different cell types, including large numbers of Reed-Sternberg cells.
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 or 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 patients.
Nodular lymphocyte-predominant Hodgkin lymphoma is more similar at the protein and genetic level to B-cell non-Hodgkin lymphoma. People with this type of Hodgkin lymphoma not only have Reed-Sternberg-like cells, but a marker called CD20 on the surface of the lymphoma cells as well. 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 than 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 the monoclonal antibody rituximab (Rituxan).
People with nodular lymphocyte-predominant Hodgkin lymphoma tend to have a very good prognosis. This means the treatment has a very good chance of being successful and helps the patient recover. However, a small number of patients 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.
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