What Is It?
Lymphoma is a cancer of the lymph (or lymphatic) system. It is part of the immune system. It collects and destroys invading organisms, such as bacteria and viruses, and abnormal cells. It protects the body from infection and disease.
The lymph system is a network of tissue, vessels, and fluid (lymph). It includes:
Lymph tissue also resides in the spleen, thymus gland, tonsils, bone marrow, and digestive system.
Lymphatic tissue is composed mainly of lymphocytes. There are two main types of lymphocytes:
Lymphoma starts when a lymphocyte changes into an abnormal cell that begins dividing out of control. These abnormal cells often form masses (tumors) in lymph nodes and elsewhere. Because lymph tissue is located throughout the body, lymphoma can begin almost anywhere. It can spread to almost any tissue or organ.
The two main types of lymphoma are Hodgkin disease (Hodgkin lymphoma) and non-Hodgkin lymphoma. There are about 30 different types of non-Hodgkin lymphoma.
Non-Hodgkin lymphoma has become more common in the past few decades. This may be related to the rise in the number of people who have a suppressed immune system, such as people infected with human immunodeficiency virus (HIV) and those who have had an organ transplant and need to take drugs that alter the immune system.
Age is a major determinant of the type of non-Hodgkin lymphoma. Slow growing lymphomas (low grade) are more likely to occur in an older person. Fast growing (high grade aggressive) non-Hodgkin lymphomas usually affect children and young adults. Lymphomas are classified by the specific characteristics of the cancer cells and the parts of the body affected.
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