What are Non-Hodgkin Lymphomas?
Lymphoma is a type of cancer that begins in the lymphocytes, which are normal cells that are a part of the immune system. These normal cells are transported throughout the body by the lymphatics, a system of small vessels that usually are found close to normal blood vessels. Lymph nodes are normal small collections of lymphocytes that are found throughout the body including clusters in the neck, under the arms, in the chest, in the abdomen, and in the groin. These nodes are connected by means of the lymphatics, and lymphocytes are free to move through these channels; they are also capable of moving throughout the body via the blood and can be found in many organs where lymph tissue is found including tonsils, spleen and bone marrow, digestive tract and thymus and also can involve any organ of the body.
There are two broad categories of lymphomas: Hodgkin lymphoma and Non-Hodgkin lymphoma. Both types are cancers that develop in lymphocytes, and have the potential to start growing and spread to other nodes or normal tissues, but can behave differently, depending on the biology of the cancer and the immune function of the person with the lymphoma.
Doctors classify non-Hodgkin lymphomas into two main groups, based on the types of cells the cancer develops from:
B-Cell Lymphomas
B-cell lymphomas develop from B lymphocytes, which are cells in the lymphoid tissue that make antibodies and protect against germs. This is the most common type of non-Hodgkin lymphoma, making up about 85% of cases. Physicians now recognize a large number of B-cell lymphomas, but here are some of the most common types:
Large B Cell Lymphomas (LBL), the most common being Diffuse Large Cell Lymphoma (DLBCL):
This is the most frequently diagnosed type of non-Hodgkin lymphoma, making up over 30% of all cases. Patients of all ages can develop this type of lymphoma, and the cause is unknown. This is a moderately aggressive form of non-Hodgkin lymphoma that usually starts in a lymph node, although half of patients have involvement of organs or sites outside of nodes at the time of original diagnosis. Most patients initially respond well to treatment, and patients who receive treatment and have no signs of the disease at the end of treatment are said to "have a complete response" to treatment or be "in remission", and more than half of these patients will be cured.
High grade B Cell lymphomas, including "Double-hit large cell lymphoma is another type of lymphoma that can be particularly aggressive and often does not respond as well to standard therapies and may require more aggressive treatment.
Follicular Lymphoma
This is most often a slower-growing type of non-Hodgkin lymphoma that accounts for about 20% of all lymphoma cases. These lymphomas often respond well to initial treatment; however follicular non-Hodgkin lymphomas are generally not considered curable with standard treatments and most often return after initial remission. There are many options for treatment when they return or recur and recent developments of newer therapies suggest that these patients can have the chance for excellent survival rates. Although less common, some follicular lymphoma can "transform" to more aggressive lymphomas.
Marginal Zone Lymphoma
About 5% to 10% of all lymphomas can be classified as marginal zone. There are types that originate in the nodes (nodal type), types that are primarily found in organs and soft tissues [extranodal types, also known as MALT (Mucosal-Associated Lymphoid Tissue) lymphomas], and types that are usually found only in the spleen and bone marrow (splenic type). The most common type of extranodal marginal zone lymphoma is found in the stomach as a result of Helicobacter pylori infection, and it is suspected that many marginal zone lymphomas are related to recognized or as yet unrecognized infections or inflammation. MALT lymphomas are slow-growing and can usually be treated with a variety of different therapies, including chemotherapy, antibody therapy, and radiotherapy.
Mantle Cell Lymphoma
This is also a type of non-Hodgkin lymphoma that makes up about 5% of all lymphoma diagnoses. Mantle cell lymphoma can be slow growing or more aggressive. This disease often responds well to initial therapy but has a high chance of recurrence and is generally not considered curable. However, like follicular lymphomas, recently developed new drugs are improving the outlook for patients with this type of cancer.
Burkitt's Lymphoma
Burkitt's lymphoma is an aggressive, fast-growing lymphoma that makes up about 1% to 2% of all diagnoses. Patients with this type of lymphoma are often younger than those with other types of lymphomas. This lymphoma often involves more than just nodes, and without proper therapy can spread to the brain or spinal cord. Doctors can often treat this successfully with intensive chemotherapy, despite its aggressive nature.
T-Cell Lymphomas
T-cell lymphomas develop from T lymphocytes, which are cells in the lymphatic system that attack viruses and other infections. They also interact with normal B cells to help them fight many types of infections. T-cell lymphomas are rarer than B-cell lymphomas and make up about 15% of all lymphoma types. Here are some of the most common forms of T-cell non-Hodgkin lymphomas:
Peripheral T-Cell Lymphoma
Peripheral T-cell lymphoma is the most common sub-type of T-cell lymphoma. Many of the patients with this cancer are older, and the cause is unknown. Peripheral T-cell lymphoma often develops in the lymph nodes and is present in areas outside of the lymph nodes. There are numerous subtypes of peripheral T Cell lymphomas. This can be an aggressive type of non-Hodgkin lymphoma and is usually treated with combination chemotherapy that will sometimes include immmunotherapy in the form of an antibody drug conjugate. New medicines are being intensively studied to try to improve results for this type of lymphoma.
Anaplastic Large Cell Lymphoma
This is an aggressive form of non-Hodgkin lymphoma that accounts for about 2% of all lymphomas, and mainly affects children and adolescents. Anaplastic large cell lymphoma usually develops in the lymph nodes, but also in the skin and other normal organs. Fortunately, this disease has a more favorable subtype that can often be cured with standard chemotherapy, and for this reason, it is very important that the pathologist recognize this particular type of T-cell lymphoma.
Lymphoblastic Lymphoma
Lymphoblastic Lymphoma is an aggressive disease, but rare, accounting for about 1% of all diagnoses. This disease mostly affects young adults and commonly develops in the thymus, an organ found in the chest. Fortunately, doctors can usually successfully treat this disease with intensive chemotherapy, similar to the type of treatment used for patients with acute lymphocytic leukemia.
