The lymphatic system is a network of nodes (knots of tissue) connected by vessels that drain fluid and waste products from the body. The lymph nodes act as tiny filters, straining out foreign organisms and cells.
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The lymphatic system also is involved in producing important white blood cells called lymphocytes that help protect you against various infections caused by bacteria, viruses, and fungi. When the lymphatic system is fighting an active infection, you may notice that some of your lymph nodes and tissue in the area of the infection become swollen and tender. This is the body's normal reaction to infection.
Lymphoma occurs when the lymph node cells or the lymphocytes begin to multiply uncontrollably, producing malignant cells that have the abnormal ability to invade other tissues throughout your body.
The two main types of lymphoma are Hodgkin lymphoma and non-Hodgkin lymphoma, which are classified by certain unique characteristics of the cancer cells.
Hodgkin disease is most common in two different age groups: young adults (ages 15 to 35) and older adults (over age 50). It is somewhat more common in males than females, and more common in Caucasians than in African-Americans. Because of progress in treating Hodgkin lymphoma, most people with a diagnosis of Hodgkin lymphoma will be long-time survivors.
What Causes Hodgkin Lymphoma?
The exact cause of Hodgkin lymphoma is not known, but the following have been implicated:
Viruses: The Epstein-Barr virus, the same virus that causes infectious mononucleosis (mono), has been implicated as a cause of Hodgkin lymphoma. The presence of the genome of this virus is seen in 20%-80% of Hodgkin lymphoma tumors.
Familial: Same-sex siblings and an identical twin of a person with Hodgkin lymphoma are at high risk of developing the disease. Children with a parent who has Hodgkin is also at an increased risk.
Environment: Fewer siblings, early birth order, single-family homes, and fewer playmates are associated with an increased risk of developing Hodgkin lymphoma -- possibly due to a lack of exposure to bacterial and viral infections at an early age.