Hodgkin disease (Hodgkin lymphoma) is a type of lymphoma, a cancer that starts in cells called lymphocytes, which are part of the body's immune system. There are 2 kinds of lymphomas:

• Hodgkin disease (named after Dr. Thomas Hodgkin, who recognized it in 1832)
• non-Hodgkin lymphoma

For information on non-Hodgkin lymphoma, see the American Cancer Society document, Non-Hodgkin Lymphoma.

The lymph system and lymphoid tissue

To better understand Hodgkin disease, it helps to know about 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 cells called lymphocytes, a type of white blood cell that fights infection. There are 2 major types of lymphocytes: B lymphocytes (B cells) and T lymphocytes (T cells). Normal T cells and B cells do different jobs within the immune system.

• B lymphocytes: B cells help protect the body from germs (bacteria and viruses). They do this by maturing into plasma cells, which make antibodies (immune proteins). These antibodies attach to the germs, marking them for destruction. Almost all cases of Hodgkin disease start in B lymphocytes.

• T lymphocytes: There are several types of T cells, and each has a specialized job. Some T cells can directly destroy certain kinds of bacteria or cells infected with viruses or fungi. Other types of T cells play a role in either boosting or slowing the activity of other immune system cells.

Organs that have lymphoid tissue

Because lymphoid tissue is found in many parts of the body, Hodgkin disease can start almost anywhere. The major sites of lymphoid tissue are listed below.

Lymph nodes: Lymph nodes are small, bean-shaped organs found throughout the body such as inside the chest, abdomen, and pelvis. They can sometimes be felt under the skin in the neck, under the arms, and in the groin.

The lymph nodes are connected by a system of lymphatic vessels. These vessels are like veins, except that instead of carrying blood, they carry lymph (a clear fluid containing waste products and excess fluid from tissues) and immune system cells.

Lymph nodes get bigger when they fight an infection. Lymph nodes that grow in reaction to infection are called reactive nodes or hyperplastic nodes and often hurt when they are touched. An enlarged lymph node is not always a sign of a serious problem. People with sore throats or colds might have enlarged lymph nodes in the neck. But a large lymph node is also the most common sign of Hodgkin disease. See the section, "How is Hodgkin disease diagnosed?" for more information.

Spleen: The spleen is an organ under the lower part of the rib cage on the left side of the body. The spleen makes lymphocytes and other immune system cells to help fight infection. 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, which is where new white blood cells (including some lymphocytes), red blood cells, and platelets are made.

Thymus: The thymus is a small organ behind the upper part of the breastbone and in front of the heart. It is important in the development of T lymphocytes.

Digestive tract: The back of the throat (adenoids and tonsils), stomach, intestines, and many other organs also have lymphoid tissue.

Start and spread of Hodgkin disease

Because lymphoid tissue is found in many parts of the body, Hodgkin disease 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, in the neck, or under the arms.

Hodgkin disease most often spreads through the lymphatic vessels to nearby lymph nodes in a stepwise fashion from lymph node to lymph node. Rarely, and late in the disease, it may invade the bloodstream and spread to other sites in the body, including the liver, lungs, and/or bone marrow.

The Hodgkin disease cell

The cancer cells in Hodgkin disease are called Reed-Sternberg cells, after the 2 doctors who first described them. These cells are usually an abnormal type of B lymphocyte. Under a microscope, Reed-Sternberg cells are much larger than normal lymphocytes and also look different from the cells of non-Hodgkin lymphomas and other cancers. In Hodgkin disease, the enlarged lymph nodes usually have a small number of Reed-Sternberg cells and a large number of normal immune cells. It is mainly these other immune cells that account for the bulkiness of the enlarged lymph nodes.

Types of Hodgkin disease

There are different types of Hodgkin disease. They are classified by how they look under the microscope. This is important because types of Hodgkin disease may grow and spread differently and may be treated differently. The 2 main types are classic Hodgkin disease (which has several subtypes) and nodular lymphocyte predominance Hodgkin disease.

Classic Hodgkin disease

Classic Hodgkin disease (HD) accounts for about 95% of all cases of Hodgkin disease in developed countries. It has 4 subtypes, all of which have classic-appearing Reed-Sternberg cells.

Nodular sclerosis Hodgkin disease: This is the most common type of Hodgkin disease in developed countries, accounting for about 60% to 80% of cases. It occurs mainly in younger people, about equally in men and women. It tends to start in lymph nodes in the neck or chest. Under the microscope, the lymph nodes contain fibrous bands that criss-cross the node and encircle abnormal nodules of lymph tissue.

Mixed cellularity Hodgkin disease: This is the second most common type (15% to 30%) and is seen mostly in older adults. It can start in any lymph node but most often occurs in the upper half of the body. Under the microscope, many different kinds of cells can be seen on the biopsy specimen, including Reed-Sternberg cells and normal immune system cells.

Lymphocyte-rich Hodgkin disease: This subtype accounts for about 5% of Hodgkin disease cases. It usually occurs in the upper half of the body and is rarely found in more than a few lymph nodes. Under the microscope it looks very much like mixed cellularity, except that most of the cells are small lymphocytes.

Lymphocyte-depleted Hodgkin disease: This is the least common form of Hodgkin disease, making up only about 1% of cases. It is seen mainly in older people. The disease is more likely to be advanced when first found, involving lymph nodes in the abdomen as well as the spleen, liver, and bone marrow. When seen under a microscope, there are few normal lymphocytes or other immune system cells, and many Reed-Sternberg cells.

Nodular lymphocyte predominant Hodgkin disease

Nodular lymphocyte predominant Hodgkin disease (NLPHD) accounts for about 5% of Hodgkin disease. It can occur at any age, and is more common in men than in women. This type usually involves lymph nodes in the neck and under the arm. It contains large cells, often called popcorn cells (because they look like popcorn), which are variants of Reed-Sternberg cells. Under the microscope, there is a pattern of sheets of lymphocytes arranged in nodules.

All types of Hodgkin disease are malignant (cancerous) because as they grow they may compress, invade, and destroy normal tissue and spread to other tissues. There is no benign (non-cancerous) form of Hodgkin disease.

Hodgkin disease occurs in both children and adults. Because Hodgkin disease is similar in both children and adults, this document discusses treatment in both groups.

Last Medical Review: 07/21/2009
Last Revised: 07/21/2009