Lymphoma is cancer that begins in lymphocytes, a type of white blood cell made in the bone marrow and found in the blood and lymph tissue. Lymphoma occurs when something goes wrong inside the lymphocytes so they don’t mature and can’t carry out their normal immune functions defending against infection. They don’t die off like they are supposed to but instead collect in the lymph nodes.
What Is Hodgkin’s Lymphoma?
There are two main types of lymphoma: Hodgkin’s lymphoma and non-Hodgkin’s lymphoma (NHL). The main difference between the two is the specific lymphocyte (white cell) involved. Hodgkin’s lymphoma involves Reed-Sternberg cells, an abnormal B-cell. NHL does not. Hodgkin’s lymphoma, named for the doctor who first recognized it, was formerly called Hodgkin’s disease.
The American Cancer Society estimated that more than 9,000 new cases of Hodgkin’s lymphoma would be diagnosed in the United States in 2013 and that 1,200 people would die from it. Hodgkin’s lymphoma can be cured or controlled for many years in most people who have the disease. The five-year relative survival rate for Hodgkin’s lymphoma is about 85 percent, according to the National Cancer Institute.
Most often Hodgkin’s lymphoma starts in the lymph nodes in the upper part of the body—in the neck or chest or under the arms. It can spread through the lymph system to nearby lymph nodes and outside the lymph nodes to the bone marrow, lungs, or liver.
The Lymph System
To understand lymphoma, it helps to have a basic knowledge of the lymph system. The lymph system is a network of tubes that slowly carries fluid from your tissues back into your bloodstream to be recycled. It has several parts.
- Lymph nodes, small bean-shaped organs that are part of the immune system and linked by lymphatic vessels. Lymph nodes store lymphocytes and act as filters to trap foreign particles. Lymph nodes are located throughout your body in your neck, underarms, and groin, and behind your knees. They are also deeper inside your body in your chest, abdomen, and pelvis.
- Lymphatic vessels, small tubes that carry lymph into your bloodstream.
- Lymph, fluid that circulates through the lymph system. It carries excess fluid and waste products from body tissues into the bloodstream. It also carries immune system cells.
- Lymph tissue, which includes lymph nodes and organs related to the immune and blood-forming systems, such as the spleen, thymus, and bone marrow.
Types of Lymphocytes
There are several kinds of lymphocytes.
- B lymphocytes, or B-cells. These make antibodies. Antibodies attach to bacteria and to cells infected with a virus or bacteria so that other immune cells recognize them and know to destroy them.
- T lymphocytes, or T-cells. There are many kinds of T-cells. They are involved in destroying invaders or tumor cells or in attracting or stimulating other immune cells to do this.
- Natural killer cells. These scout for cells that do not look normal and destroy them.
There are two types of Hodgkin’s lymphoma. Correct identification—by examining cells from biopsied tissue under a microscope—is important in deciding which treatments are most likely to be effective.