Hodgkin lymphoma

Hodgkin lymphoma or Hodgkin’s lymphoma (HL) is a blood cancer that occurs in the lymph system, also called the lymphatic system. It is marked by the involvement of Reed-Sternberg cells, which differentiates it from Non-hodgkin lymphoma (NHL).

Five-year Hodgkin lymphoma cancer survival rates

Overview

The lymph system helps control the flow of fluids in the body and is part of the immune system. The lymph system consists mainly of a type of white blood cell called lymphocytes—there are two main types:

  • T lymphocytes (T cells). There are many types of T cells. Some T cells destroy germs or abnormal cells in the body, while other T cells help boost or slow the activity of other immune system cells.
  • B lymphocytes (B cells). They make proteins called antibodies that help protect the body from bacteria and viruses. Hodgkin lymphoma usually starts in B cells.

Lymph tissue is in many parts of your body, so Hodgkin lymphoma can start almost anywhere.

Major sites of lymphoid tissue

  • Lymph nodes. Lymph nodes are bean-sized collections of lymphocytes and other immune system cells. They’re found throughout the body, including inside the chest, abdomen (belly), and pelvis. They’re connected to each other by a system of lymphatic vessels.
  • Lymph vessels. A network of tiny tubes (a lot like blood vessels) that connect lymph nodes and carry immune cells in a clear fluid called lymph. Lymph is collected from around the body and put into the bloodstream.
  • Spleen. The spleen is an organ that’s under the lower ribs on your left side. The spleen is part of your immune system. It 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 liquid, spongy tissue inside certain bones. New blood cells (including some lymphocytes) are made there.
  • Thymus. The thymus is a small organ behind the upper part of the breastbone and in front of the heart. It’s important for T lymphocyte development.
  • Adenoids and tonsils. These are collections of lymph tissue in the back of your 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.

Although Hodgkin lymphoma can start almost anywhere, most often it starts in lymph nodes in the upper part of the body. The most common sites are in the chest, neck, or under the arms.

Hodgkin lymphoma most often spreads through the lymph vessels from lymph node to lymph node. Rarely, late in the disease, it can invade the bloodstream and spread to other parts of the body, such as the liver, lungs, and/or bone marrow.

 

We know that Hodgkin lymphoma is linked with a number of risk factors, but we are still researching the cause of most lymphomas.

Genetic causes

We do have a better understanding now how certain changes in DNA can cause normal lymphocytes to become lymphoma cells. Oncogenes are genes that help cells grow, divide, and stay alive—tumor suppressor genes help keep cell division under control, or make cells die at the right time. We know that some lymphoma cancers are caused by DNA mutations that turn on oncogenes or turn off tumor suppressor genes. A family history of lymphoma does seem to increase the risk of lymphoma.

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Different types of HL can grow and spread differently and may be treated differently.

Classic Hodgkin lymphoma (cHL). Accounts for more than 90% of cases of Hodgkin lymphoma in developed countries. The cancer cells in cHL are called Reed-Sternberg cells, usually an abnormal type of B lymphocyte.

Classic HL has four subtypes:

  • Nodular sclerosis Hodgkin lymphoma (NSCHL). The most common type of Hodgkin disease in developed countries, accounting for about seven out of 10 cases. Typically starts in lymph nodes in the neck or chest.
  • Mixed cellularity Hodgkin lymphoma (MCCHL). The second-most common type, occurring mostly in people with HIV infection. It can start in any lymph node, but most often occurs in the upper half of the body.
  • Lymphocyte-rich Hodgkin lymphoma. Not common. Usually occurs in the upper half of the body and is found in only a few lymph nodes.
  • Lymphocyte-depleted Hodgkin lymphoma. A rare form of Hodgkin disease, occurring mainly in older people and those with HIV infection. Found most often in lymph nodes in the abdomen as well as in the spleen, liver, and bone marrow. It’s more aggressive than other types, and likely to be advanced when discovered.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL). Accounts for about 5% of cases. The cancer cells are large and called popcorn cells because they look like popcorn—they are also called lymphocytic and histiocytic (L&H) cells—which are variants of Reed-Sternberg cells. NLPHL typically starts in lymph nodes in the neck and armpit and tends to grow slower and is treated differently from cHL types.