Non-Hodgkin lymphoma is cancer that begins in cells of the immune system. The immune system fights infections and other diseases.
The lymphatic system is part of the immune system. The lymphatic system includes the following:
- Lymph vessels: The lymphatic system has a network of lymph vessels. Lymph vessels branch into all the tissues of the body.
- Lymph: The lymph vessels carry clear fluid called lymph. Lymph contains white blood cells, especially lymphocytes such as B cells and T cells.
- Lymph nodes: Lymph vessels are connected to small, round masses of tissue called lymph nodes. Groups of lymph nodes are found in the neck, underarms, chest, abdomen, and groin. Lymph nodes store white blood cells. They trap and remove bacteria or other harmful substances that may be in the lymph.
- Other parts of the lymphatic system: Other parts of the lymphatic system include the tonsils, thymus, and spleen. Lymphatic tissue is also found in other parts of the body including the stomach, skin, and small intestine.
Because lymphatic tissue is in many parts of the body, Hodgkin lymphoma can start almost anywhere. Usually, it's first found in a lymph node.
Non-Hodgkin Lymphoma Cells
Non-Hodgkin lymphoma begins when a lymphocyte (usually a B cell) becomes abnormal. The abnormal cell divides to make copies of itself. The new cells divide again and again, making more and more abnormal cells. The abnormal cells don't die when they should. They don't protect the body from infections or other diseases. The buildup of extra cells often forms a mass of tissue called a growth or tumor.
Doctors seldom know why one person develops non-Hodgkin lymphoma and another does not. But research shows that certain risk factors increase the chance that a person will develop this disease.
In general, the risk factors for non-Hodgkin lymphoma include the following:
- Weakened immune system: The risk of developing lymphoma may be increased by having a weakened immune system (such as from an inherited condition or certain drugs used after an organ transplant).
- Certain infections: Having certain types of infections increases the risk of developing lymphoma. However, lymphoma is not contagious. You cannot catch lymphoma from another person.
The following are the main types of infection that can increase the risk of lymphoma:
- Human immunodeficiency virus (HIV): HIV is the virus that causes AIDS. People who have HIV infection are at much greater risk of some types of non-Hodgkin lymphoma.
- Epstein-Barr virus (EBV): Infection with EBV has been linked to an increased risk of lymphoma. In Africa, EBV infection is linked to Burkitt lymphoma.
- Helicobacter pylori: H. pylori are bacteria that can cause stomach ulcers. They also increase a person's risk of lymphoma in the stomach lining.
- Human T-cell leukemia/lymphoma virus type 1 (HTLV-1): Infection with HTLV-1 increases a person's risk of lymphoma and leukemia.
- Hepatitis C virus: Some studies have found an increased risk of lymphoma in people with hepatitis C virus. More research is needed to understand the role of hepatitis C virus.
- Age: Although non-Hodgkin lymphoma can occur in young people, the chance of developing this disease goes up with age. Most people with non-Hodgkin lymphoma are older than 60. (For information about this disease in children, call the NCI's Cancer Information Service at 1-800-4-CANCER.)
Researchers are studying obesity and other possible risk factors for non-Hodgkin lymphoma. People who work with herbicides or certain other chemicals may be at increased risk of this disease. Researchers are also looking at a possible link between using hair dyes before 1980 and non-Hodgkin lymphoma.
Having one or more risk factors does not mean that a person will develop non-Hodgkin lymphoma. Most people who have risk factors never develop cancer.
Non-Hodgkin lymphoma can cause many symptoms:
- Swollen, painless lymph nodes in the neck, armpits, or groin
- Unexplained weight loss
- Soaking night sweats
- Coughing, trouble breathing, or chest pain
- Weakness and tiredness that don't go away
- Pain, swelling, or a feeling of fullness in the abdomen
Most often, these symptoms are not due to cancer. Infections or other health problems may also cause these symptoms. Anyone with symptoms that do not go away within 2 weeks should see a doctor so that problems can be diagnosed and treated.
If you have swollen lymph nodes or another symptom that suggests non-Hodgkin lymphoma, your doctor will try to find out what's causing the problem. Your doctor may ask about your personal and family medical history.
You may have some of the following exams and tests:
- Physical exam: Your doctor checks for swollen lymph nodes in your neck, underarms, and groin. Your doctor also checks for a swollen spleen or liver.
- Blood tests: The lab does a complete blood count to check the number of white blood cells. The lab also checks for other cells and substances, such as lactate dehydrogenase (LDH). Lymphoma may cause a high level of LDH.
- Chest x-rays: You may have x-rays to check for swollen lymph nodes or other signs of disease in your chest.
- Biopsy: A biopsy is the only sure way to diagnose lymphoma. Your doctor may remove an entire lymph node (excisional biopsy) or only part of a lymph node (incisional biopsy). A thin needle (fine needle aspiration) usually cannot remove a large enough sample for the pathologist to diagnose lymphoma. Removing an entire lymph node is best. The pathologist uses a microscope to check the tissue for lymphoma cells.
Types of Non-Hodgkin Lymphoma
When lymphoma is found, the pathologist reports the type. There are many types of lymphoma. The most common types are diffuse large B-cell lymphoma and follicular lymphoma.Lymphomas may be grouped by how quickly they are likely to grow:
- Indolent (also called low-grade) lymphomas grow slowly. They tend to cause few symptoms.
- Aggressive (also called intermediate-grade and high-grade) lymphomas grow and spread more quickly. They tend to cause severe symptoms. Over time, many indolent lymphomas become aggressive lymphomas.
It's a good idea to get a second opinion about the type of lymphoma that you have. The treatment plan varies by the type of lymphoma. A pathologist at a major referral center can review your biopsy. See the Second Opinion section for more information.