What is Hodgkin lymphoma?
Hodgkin lymphoma (also known as Hodgkin's disease) is cancer that develops from cells in the lymphatic system (part of the body's immune system) called lymphocytes. Lymphocytes are a type of white blood cell that helps the body fight infections. All other lymphomas are classified as non-Hodgkin lymphoma (NHL).
Hodgkin lymphoma incidence
Hodgkin lymphoma is considered rare, accounting for about 0.5 percent of all cancers in the United States, according to the National Cancer Institute.
Among lymphomas, Hodgkin lymphoma is much less common than non-Hodgkin lymphoma, which is the seventh most common type of cancer in males and females in the United States.
Although Hodgkin lymphoma can occur at any age, it is most common between the ages of 55 and 84. The median age at diagnosis is 66.
How Hodgkin lymphoma develops
Named after the doctor who identified it in 1832 (Dr. Thomas Hodgkin), Hodgkin lymphoma is distinguished from the other lymphomas by the way it looks under a microscope, and by the way it grows and spreads:
- In Hodgkin lymphoma, the pattern of spread is orderly, progressing from one group of lymph nodes to the next via the lymphatic vessels. Also, the disease rarely skips over an area of lymph nodes as it spreads.
- Unlike non-Hodgkin lymphoma, Hodgkin lymphoma is marked by the presence of an abnormal lymphocyte called the Reed-Sternberg cell (or B lymphocyte). These distinctive cells are larger than normal lymphocytes and have large, pale nuclei.
Most often, Hodgkin lymphoma starts in the lymph nodes in the upper part of the body (the chest, neck, or under the arms). The disease causes the lymphatic tissue to become enlarged and press on nearby structures. Since lymph tissues are all connected, lymphoma can spread from one lymph node to another throughout the body.