Non-Hodgkin lymphoma (NHL) is cancer that begins in lymphocytes, white blood cells that are an important part of the body’s infection-fighting immune system.
What is non-Hodgkin lymphoma?
In people with lymphoma, something goes wrong inside the lymphocytes.
- Lymphocytes are a type of white blood cell made in the bone marrow and found in the blood and lymph tissue.
- In lymphoma, the lymphocytes don’t mature and can’t carry out their normal immune functions defending against infection.
- The lymphoma cells don’t die off like they should but instead collect in the lymph nodes.
- NHL can spread through the lymph system to other lymph nodes and outside the lymph nodes to the bone marrow, lungs or liver.
- NHL can be cured or controlled for many years in many people who have the disease.
Understanding your lymph system
To understand lymphoma, it helps to have a basic knowledge of the lymph system.
What is the lymph system?
The lymph system is a network of tubes (lymphatic vessels) that slowly carry fluid from your tissues into your bloodstream to be recycled. The fluid (lymph) contains waste products from body tissues as well as immune system cells.
What are lymph nodes?
Lymph nodes are small bean-shaped organs linked by your lymphatic vessels. They are part of your immune system. They store lymphocytes and act as filters to trap foreign particles.
Where are these nodes?
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 pelvic area.
What else makes up the lymph system?
Along with lymph nodes, you have other lymph tissue, including organs related to your immune and blood-forming systems, such as your spleen, thymus and bone marrow.
How do lymphocytes protect the body?
There are several types 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. These 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 abnormal cells and destroy them.
Types of NHL
It’s important to correctly identify the type and subtype of your lymphoma to determine which treatments are most likely to be effective.
There are two main types of lymphoma:
- Hodgkin lymphoma, which involves Reed-Sternberg cells, abnormal B cells
- Non-Hodgkin lymphoma, in which there are no Reed-Sternberg cells
Within NHL, there are about 60 types and subtypes based on:
- Whether the disease originates from B cells or T cells
- Whether it is fast or slow growing
- How and where the cells grow in the body
- The genetic characteristics and other molecular features of the cells affected
- Their appearance under a microscope
B-cell lymphoma or T-cell lymphoma?
Most NHLs — about 90 percent — begin in the B cells. The most common subtype of B-cell lymphoma is diffuse large B-cell lymphoma, but there are several other NHL B-cell subtypes.
About 10 percent of NHLs begin in the T cells. In some of these, natural killer cells are also involved. These are called NK/T-cell lymphomas. Read more about NHL T-cell subtypes.
Cutaneous lymphoma, a rare NHL, may be either B-cell or T-cell type. It occurs mainly in the skin but may involve lymph nodes, blood and other organs.
Indolent lymphoma or aggressive lymphoma?
NHLs are often described by how quickly they grow.
- Indolent (low-grade) NHL tends to grow slowly and cause fewer symptoms. The most common indolent subtype is follicular lymphoma. Over time, indolent NHL may transform into aggressive NHL.
- Aggressive (high-grade) NHL tends to grow and spread quickly and cause severe symptoms. The most common aggressive subtype is diffuse large B-cell lymphoma.
Some subtypes have features of both indolent and aggressive disease, making them difficult to classify into either group.
Where did the lymphoma start?
Names of some NHL subtypes relate to the area where the disease originates.
- Nodal lymphomas originate in the lymph nodes.
- Extranodal lymphomas start in places other than the lymph nodes.
- Follicular lymphoma usually starts in the follicle cells in the lymph, and it grows in a follicular pattern, meaning the cells clump together.
- Mantle cell lymphoma originates in the mantle zone, or outer layer, of the lymph node.
- Marginal lymphomas start in the interface (margin) between lymphoid and non-lymphoid pulp in the spleen and lymph nodes.
Symptoms of NHL
Symptoms of NHL can come on very quickly. Some people are diagnosed with the disease within days to weeks of getting symptoms. Some types of NHL come on slowly over several months.
NHL symptoms may be similar to symptoms caused by other conditions that are not related to cancer. Check with your doctor if you feel concerned about any symptoms you have.
Symptoms of NHL include:
- Painless swollen lymph nodes in your neck, underarm, groin, chest or abdomen
- Unexplained fever, weight loss or night sweats
- Ongoing fatigue
- Itchy skin
- Red bumps on your skin
- Swelling in your face, neck or upper chest
- Feeling of fullness in your abdomen (from an enlarged liver, spleen or lymph nodes)
- Abdominal problems, such as nausea, vomiting and indigestion
If your doctor suspects you may have lymphoma, they will do a physical exam to look for signs of the disease and ask about your health history.
To confirm the presence of lymphoma, you will need a biopsy. This means removing part or all of a lymph node or a small sample of tissue surgically or with a needle. Experts in identifying blood-related cancers (hematopathologists) look at the cells under a microscope to diagnose the disease and accurately identify the type.
You might also have any or all of these tests:
- Imaging tests — such as a chest X-ray, ultrasound, magnetic resonance imaging (MRI), computed tomography (CT) scan or positron emission tomography (PET) scan to see pictures of the inside of your body and look for enlarged lymph nodes, tumors or other cancer activity
- Blood tests — to check the types and numbers of blood cells (complete blood count) and look for chemicals that signal disease in certain organs or tissues (blood chemistry analysis)
- Lumbar puncture — taking a sample of cerebrospinal fluid from your spine with a needle to check for cancer cells
- Bone marrow tests — taking samples of bone marrow and a small piece of bone from your pelvis using a needle (bone marrow aspiration and biopsy) to check for cancer cells
If you have lymphoma, you may need more tests to identify the type or subtype. These include an immunohistochemistry study; immunophenotyping, or flow cytometry; and cytogenetic analysis.
Stages of NHL
Staging means finding out how far lymphoma has spread in your lymph system or other parts of your body. Accurate staging allows your doctors to choose the most appropriate therapy for you — and help you avoid therapy that is not likely to be effective in your situation.
NHLs range from stage I to stage IV, with I being the least advanced and IV being the most advanced.
Doctors may add a letter after your stage to describe more about your disease.
- E (such as “stage IIIE”) means your cancer is outside your lymph nodes (extranodal).
- S (such as “stage IIIS”) means the cancer is in your spleen.
If your lymphoma comes back after treatment, it is called recurrent or relapsed. Your doctor will order imaging or other tests to restage it.
How common is NHL?
NHL is one of the most common cancers in the United States, with about 72,000 people newly diagnosed each year.
What causes NHL?
Doctors do not know what causes NHL. It is more common in men than in women, and the risk increases with age.
You may be at higher risk if any of these is true:
- Your immune system is weakened by an inherited disease, autoimmune disease, human immunodeficiency virus (HIV) or drugs given because you had an organ transplant.
- You have been infected with human T-lymphotropic virus type I (HTLV-1), Epstein-Barr virus (which causes mononucleosis), Helicobacter pylori (a bacterium that causes ulcers) or hepatitis C virus.
- You were exposed to certain chemicals, such as ingredients in pesticides, herbicides, solvents or fertilizers.
Keep in mind that many people who get the disease have none of these risk factors, and most people with these risk factors do not develop the disease.