What is non-Hodgkin lymphoma?
Non-Hodgkin lymphoma (also known as non-Hodgkin's lymphoma, NHL, or sometimes just lymphoma) is a cancer that starts in cells called lymphocytes, which are part of the body's immune system. Lymphocytes are in the lymph nodes and other lymphoid tissues (such as the spleen and bone marrow). These will be described in more detail in the section "The lymph system and lymphoid tissue."
Some other types of cancer -- lung or colon cancers, for example -- can spread to lymph tissue such as the lymph nodes or bone marrow. But cancers that start in these places and then spread to the lymph tissue are not lymphomas.
There are 2 main types of lymphomas.
Hodgkin lymphoma (also known as Hodgkin's lymphoma, Hodgkin disease, or Hodgkin's disease) is named after Dr. Thomas Hodgkin, who first described it.
non-Hodgkin lymphoma
These 2 types of lymphomas differ in how they behave, spread, and respond to treatment.
Doctors can usually tell the difference between them by looking at the cancer cells under a microscope. In some cases, sensitive lab tests may be needed to tell them apart.
The lymph system and lymphoid tissue
To understand what lymphoma is, it helps to know about the body's lymph system.
The lymph system (also known as the lymphatic system) is composed mainly of lymphoid tissue, lymph vessels, and a clear fluid called lymph. Lymphoid tissue is made up of several types of immune system cells that work together to help the body fight infections. Lymphoid tissue is found in many places throughout the body (described below).
LymphocytesMost of the cells in lymphoid tissue are lymphocytes, a type of white blood cell. The 2 main types of lymphocytes are B lymphocytes (B cells) and T lymphocytes (T cells). Both types can develop into lymphoma cells, but B-cell lymphomas are much more common than T-cell lymphomas in the United States. Normal T cells and B cells do different jobs within the immune system.
B lymphocytes: B cells normally help protect the body against germs (bacteria or viruses) by making proteins called antibodies. The antibodies attach to the bacteria or viruses and attract other immune system cells that surround and digest the antibody-coated germs. Antibodies also attract certain blood proteins that can kill bacteria.
T lymphocytes: There are several types of T cells, each with a specialized job. Some T cells help protect the body against viruses, fungi, and some bacteria. For example, they recognize specific substances found in virus-infected cells and destroy these cells. T cells can also release substances called cytokines that attract certain other types of white blood cells, which then digest the infected cells. T cells are also thought to destroy some types of cancer cells. Some types of T cells play a role in either boosting or slowing the activity of other immune system cells.
Different types of lymphoma can develop from these different types of lymphocytes. Treatment for each lymphoma depends on which type it is, so determining the exact type of lymphoma is important.
Organs that contain lymphoid tissueBecause lymphoid tissue is in many parts of the body, lymphomas can start almost anywhere. The major sites of lymphoid tissue are:
Lymph nodes: Lymph nodes are bean-sized organs throughout the body that are connected by a system of lymphatic vessels. These vessels are like veins, except that instead of carrying blood, they carry lymph and immune system cells.
Lymph nodes get bigger when they fight infection. Lymph nodes that grow in reaction to infection are called reactive nodes or hyperplastic nodes and are often tender to the touch. An enlarged lymph node is not always a sign of a serious problem. Enlarged lymph nodes in the neck are often felt in people with sore throats or colds. But a large lymph node is also the most common sign of lymphoma. Lymph node enlargement is discussed more in the section, "How is non-Hodgkin lymphoma diagnosed?"
Spleen: The spleen is an organ under the lower part of the rib cage on the left side of the body. An average adult spleen weighs about 5 ounces. The spleen makes lymphocytes and other immune system cells to help fight infection. It also stores healthy blood cells and filters out damaged blood cells, bacteria, and cell waste.
Thymus gland: The thymus lies behind the upper part of the breastbone and in front of the heart. Before birth, the thymus plays a vital role in development of T lymphocytes. The thymus shrinks and becomes less important over the first 20 years of life. Despite this, it continues to play a role in immune system function.
Adenoids and tonsils: These are collections of lymphoid tissue located at the back of the throat. They help make antibodies against germs that are breathed in or swallowed. They are easy to see when they become enlarged during an infection or if they become cancerous.
Digestive tract: The stomach and intestines as well as many other organs also contain lymphoid tissue.
Bone marrow: The bone marrow (the soft inner part of certain bones) makes red blood cells, blood platelets, and white blood cells. Red blood cells carry oxygen from the lungs to the rest of the body. Platelets plug up small holes in blood vessels caused by cuts or scrapes. White blood cells' main job is fighting infections. The 2 main types of white blood cells are granulocytes and lymphocytes. Bone marrow lymphocytes are primarily B cells. Lymphomas sometimes start from bone marrow lymphocytes.
Types of non-Hodgkin lymphoma
Classifying non-Hodgkin lymphoma can be quite confusing (even for many doctors) because there are so many types and because several different systems have been used. The most recent system is the World Health Organization (WHO) classification. The WHO system groups lymphomas based on how they look under a microscope, the chromosome features of the lymphoma cells, and the presence of certain chemicals on the surface of the cells. (Older systems classified lymphomas based only on how they looked under a microscope.)
The more common types of lymphoma are listed below according to whether they are B-cell or T-cell lymphomas. Some rarer forms of non-Hodgkin lymphoma are not discussed here.
B-cell lymphomas
B-cell lymphomas make up most (about 85%) of non-Hodgkin lymphomas in the United States.
Diffuse large B-cell lymphoma This is one of the more common types of non-Hodgkin lymphoma in the United States, accounting for about 1 out of every 3 cases. The cells are fairly large when viewed under the microscope.
Diffuse large B-cell lymphoma (DLBCL) can affect any age group but occurs mostly in older people (the average age is mid-60s). It usually starts as a quickly growing mass in an internal lymph node, such as in the chest or abdomen or in a lymph node that you can feel, such as in the neck or armpit. Although this lymphoma usually starts in lymph nodes, it can grow in other areas such as the intestines, bone, or even the brain or spinal cord.
About 1 out of 3 of these lymphomas is confined to one part of the body (localized) when it is found. Localized lymphomas are easier to treat than when they have spread to other parts of the body. Genetic tests have shown that there are different subtypes of DLBCL, even though they look the same under the microscope. These subtypes seem to have different outlooks (prognoses) and responses to treatment.
This is a fast growing lymphoma, but it often responds well to treatment with chemotherapy. Overall, about 3 out of 4 people will have no signs of disease after initial treatment, and about half of all people with this lymphoma are cured with therapy.
Follicular lymphomaAbout 1 out of 5 lymphomas in the United States is follicular lymphoma. The term follicular is used because the cells tend to grow in a circular, or nodular, pattern in lymph nodes.
The average age for people with this lymphoma is about 60. It is rare in very young people. Most of the time, this lymphoma occurs in many lymph node sites in the body, as well as in the bone marrow.
Follicular lymphomas are often slow-growing, but they are hard to cure. The 5-year survival rate (the percentage of people surviving at least 5 years) is around 70%. Often these lymphomas are not treated when they are first diagnosed if the patient has no symptoms of the disease. Over time, about 1 out of 3 follicular lymphomas changes (transforms) into a fast-growing diffuse B-cell lymphoma.
Chronic lymphocytic leukemia /small lymphocytic lymphoma These are closely related diseases. In fact, many doctors consider them to be different versions of the same disease. The same type of cell (known as a small lymphocyte) is involved in both chronic lymphocytic leukemia (CLL) and small lymphocytic leukemia (SLL). The only difference is where the cancer occurs. In CLL it is mostly in the blood and bone marrow; in SLL, it is mainly in the lymph nodes. SLL accounts for about 5% to 10% of all lymphomas.
Both CLL and SLL are slow-growing diseases, although CLL, which is much more common, tends to grow slower. CLL and SLL are treated the same way. They are usually not considered curable with standard treatments, but depending on the stage and growth rate of the disease, most patients live longer than 10 years. Occasionally over time, these slow-growing lymphomas may transform into a more aggressive type of lymphoma.
For more detailed information, see our document, Leukemia -- Chronic Lymphocytic.
Mantle cell lymphomaOnly about 5% of lymphomas are of this type. The cells are small to medium in size.
Men are affected most often. The average age of patients is in the early 60s. The lymphoma is usually widespread when it is diagnosed, involving lymph nodes, bone marrow, and, very often, the spleen.
This isn't a very fast growing lymphoma, but it is hard to treat. Newer, more aggressive treatments may be more effective than those used in the past, and may offer a better chance for long-term survival for patients now being diagnosed.
Marginal zone B-cell lymphomasMarginal zone lymphomas account for about 5% to 10% of lymphomas. The cells in these lymphomas look small under the microscope. There are 3 main types of marginal zone lymphomas.
Extranodal marginal zone B-cell lymphomas, also known as mucosa-associated lymphoid tissue (MALT) lymphomas: These lymphomas start in places other than the lymph nodes (hence the name extranodal) and are the most common type. Most MALT lymphomas arise in the stomach and are thought to be related to an infection by the bacteria Helicobacter pylori, which is also the cause of stomach ulcers. Other possible sites of MALT lymphomas include the lung, skin, thyroid, salivary glands, and tissues surrounding the eye. Usually it is confined to the area where it begins and is not widespread. Many of these other MALT lymphomas have also been linked to infections with bacteria or viruses.
The average age of patients with MALT lymphoma is about 60. It is a slow-growing lymphoma and is often curable in its early stages. Doctors often use antibiotics as the first treatment for this type of lymphoma, especially MALT lymphoma of the stomach, as they may get rid of the Helicobacter pylori infection.
Nodal marginal zone B-cell lymphoma: This is a rare disease, found mainly in older women. Mostly lymph nodes are involved, although the lymphoma cells can also sometimes be found in the bone marrow.
This tends to be a slow-growing lymphoma (although not usually as slow as MALT lymphoma), and many patients are cured if they are diagnosed in the early stages.
Splenic marginal zone B-cell lymphoma: This is a rare lymphoma. Most often the lymphoma is found only in the spleen and bone marrow.
Patients are often elderly and male and have fatigue and discomfort caused by an enlarged spleen. Because the disease is slow-growing, treatment may not be needed unless the symptoms become troublesome.
Primary mediastinal B-cell lymphoma This type accounts for about 2% of all lymphomas. The cells are large and resemble those of diffuse large B-cell lymphomas.
This lymphoma starts in the mediastinum (the area around the heart and behind the chest bone). It usually is localized when it is found and rarely involves the bone marrow. It can cause trouble breathing because it often presses on the windpipe (trachea) leading into the lungs. It can also block the superior vena cava (the large vein that returns blood to the heart from the arms and head). This can cause the arms and face to swell.
About 2 out of 3 people with this lymphoma are women. Most are young -- in their 30s. It is a fast growing lymphoma but it is treatable. About half of patients can be cured.
Burkitt lymphomaThis type makes up about 1% to 2% of all lymphomas. It is named after the doctor who first described this disease in African children and young adults. The cells are medium sized. Another kind of lymphoma, called Burkitt-like lymphoma, has slightly larger cells. Because this second kind of lymphoma is hard to tell apart from Burkitt lymphoma, the WHO classification combines them.
This is a very fast-growing lymphoma. In the African variety, it often starts as tumors of the jaws or other facial bones. In the more common types seen in the United States, the lymphoma usually starts in the abdomen, where it forms a large tumor mass. It can also start in the ovaries, testes, or other organs, and can spread to the brain and spinal fluid.
Close to 90% of patients are male, and the average age is about 30. Although this is a fast-growing lymphoma, over half of patients can be cured by intensive chemotherapy.
Lymphoplasmacytic lymphoma (Waldenstrom macroglobulinemia)This type is not common, accounting for 1% to 2% of lymphomas. The cells are small and found mainly in the bone marrow, lymph nodes, and spleen.
Most of the time the lymphoma cells make an antibody called immunoglobulin M (IgM), which is a very large protein. This antibody circulates in the blood in large amounts, and causes the liquid part of the blood to thicken, like syrup. This can lead to decreased blood flow to many organs, which can cause problems with vision (because of poor circulation in blood vessels in the back of the eyes) and neurological problems (such as headache, dizziness, and confusion) caused by poor blood flow within the brain. Other symptoms can include feeling tired and weak, and a tendency to bleed easily.
This lymphoma is slow growing. Although it isn't usually considered to be curable, most patients live longer than 5 years.
For more information, see our document, Waldenstrom Macroglobulinemia.
Hairy cell leukemiaDespite the name, this is sometimes considered to be a type of lymphoma. Hairy cell leukemia (HCL) is rare -- about 1,000 people in the United States are diagnosed with it each year. The cells are small B lymphocytes with projections coming off them that give them a "hairy" appearance. They are typically found in the bone marrow and spleen and circulating in the blood.
Patients with HCL tend to be older in general. Hairy cell leukemia is slow-growing, and some patients may never need treatment. An enlarging spleen or dropping blood counts (due to cancer cells invading the bone marrow) are the usual reasons to begin treatment, which is highly effective. Hairy cell leukemia is also described in our document, Leukemia--Chronic Lymphocytic.
Primary central nervous system (CNS) lymphomaThis lymphoma usually involves the brain (called primary brain lymphoma), but it may also be found in the spinal cord and in tissues around the spinal cord and the eye. Over time, it tends to become widespread in the central nervous system. Primary CNS lymphoma is more common in people with immune system problems, such as those infected with HIV, the virus that causes AIDS. Most people develop headaches and confusion. They can also have vision problems, paralysis of some facial muscles, and even seizures in some cases.
The outlook for people with this condition has always been thought to be fairly poor, but about 30% to 50% of people can live at least 5 years with today's treatments.
T-cell lymphomas
T-cell lymphomas make up less than 15% of non-Hodgkin lymphomas in the United States.
Precursor T-lymphoblastic lymphoma/leukemiaThis disease accounts for about 1% of all lymphomas. It can be considered either a lymphoma or leukemia, depending on how much of the bone marrow is involved (leukemias have more bone marrow involvement). The cancer cells are small-to-medium sized immature T-cells.
It often starts in the thymus gland (where many T cells are made) and can develop into a large tumor in the mediastinum (the area around the heart and behind the breast bone). This can cause trouble breathing if it presses on the windpipe (trachea) leading into the lungs. It can also block the superior vena cava (the large vein that returns blood to the heart from the arms and head), which can cause the arms and face to swell.
Patients are most often young adults, with males being affected more often than females.
This lymphoma is fast-growing, but if it hasn't spread to the bone marrow when it is first diagnosed, the chance of cure with chemotherapy is quite good. Once it is in the bone marrow, only about 40% to 50% of patients can be cured.
Peripheral T-cell lymphomasThese types of lymphomas develop from more mature forms of T cells. They are rare, accounting for about 5% of all lymphomas.
Cutaneous T-cell lymphomas (mycosis fungoides, Sezary syndrome): These lymphomas start in the skin. They are described in our document, Lymphoma of the Skin.
Angioimmunoblastic T-cell lymphoma: This lymphoma tends to occur in the lymph nodes and may affect the spleen or liver. Patients usually have fever, weight loss, and skin rashes and often develop infections. This lymphoma often progresses quickly.
Extranodal natural killer/T-cell lymphoma, nasal type: This type often involves the upper airway passages, such as the nose and upper throat, but it can also invade the skin and digestive tract. It is much more common in parts of Asia and South America. All ages can be affected.
Enteropathy type T-cell lymphoma: This lymphoma occurs in people with sensitivity to gluten, the main protein in wheat flour. The disease, called gluten-sensitive enteropathy, can progress to this lymphoma, which typically invades the walls of the intestines.
Subcutaneous panniculitis-like T-cell lymphoma: This rare lymphoma invades the deep layers of the skin, where it causes nodules to form. It is described further in our document, Lymphoma of the Skin.
Anaplastic large cell lymphoma: About 1% to 2% of lymphomas are of this type. The cells appear large under the microscope. The type of lymphoma is more common in young people (including children), but it does occur in patients in their 50s and 60s. It usually starts in lymph nodes and can also spread to skin. This type of lymphoma tends to be fast-growing, but many patients with this lymphoma are cured.
Peripheral T-cell lymphoma, unspecified: This name is given to T-cell lymphomas that don't readily fit into any of the groups above. They make up about half of all T-cell lymphomas. The tumor cells can be small or large. Most patients are in their 60s. As a group, these lymphomas tend to be widespread and grow quickly. Some cases respond well to chemotherapy, but long-term survival is not common.
