[21]
An introduction to non-hodgkin's lymphoma
Lymphomas, such as non-Hodgkin's lymphomas and Hodgkin's disease, represent tumors of the lymphatic system. This system is a network of organs, ducts, and nodes. The system interacts with the blood's circulatory system to transport a watery clear fluid called lymph throughout the body. The lymphatic system contains lymphocytes, important cells involved in defending the body against infectious organisms. This system also restores 60% of the fluid that leaks out from blood capillaries back into circulation, and its ducts provide transportation for fats, proteins, and other substances collected from the body's tissues.Non-Hodgkin lymphomas can occur at any age and are often marked by lymph nodes that are larger than normal, fever, and weight loss.[3]
An exact cause of Non-Hodgkin Lymphoma is still unknown. Scientists have not yet identified what exactly makes a lymphocyte go haywire and transform into a lymphoma cell. But there are some conditions that make a person more likely to get a Non-Hodgkin Lymphoma. However, we know that this cancer might cause by microbes or a weak immune system. An association has been found between Non-Hodgkin Lymphoma and certain infections - HTLV-1, Epstein-Barr (EBV) virus, Hepatitis C virus, Helicobacter pylori, a bacteria that may cause lymphomas of the stomach and HIV, the "AIDS" virus. Infection with any of these increases the risk of later development of lymphoma. It is possible that these microbes may enter the lymphocytes and change them into cancer cells. Lymhoma is a cancer of the immune system. Conditions which weaken the immune system may also result in a hgher risk of developing lymphomas.The most talked about is HIV, which caused AIDS ( a kind of immune failure disease). Patients who get organ transplantation need to take drugs which suppress the immune system. This also seems to increase chances of lymphoma. Some inherited diseases affecting the immune.[4]
There are many different types of non-Hodgkin lymphoma. These types can be divided into aggressive (fast-growing) and indolent (slow-growing) types, and they can be formed from either B-cells or T-cells. B-cell non-Hodgkin lymphomas include Burkitt lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), diffuse large B-cell lymphoma, follicular lymphoma, immunoblastic large cell lymphoma, precursor B-lymphoblastic lymphoma, and mantle cell lymphoma. T-cell non-Hodgkin lymphomas include mycosis fungoides, anaplastic large cell lymphoma, and precursor T-lymphoblastic lymphoma. Lymphomas that occur after bone marrow or stem cell transplantation are usually B-cell non-Hodgkin lymphomas.[5]
The lymphatic system is involved in the production and transportation of lymphocytes, white blood cells that are a primary component of the immune system. Among other vital functions, certain lymphocytes are responsible for producing antibodies, factors that can target and attack specific foreign proteins (antigens). Lymphocytes develop in the bone marrow or thymus gland and are therefore categorized as either B cells (bone marrow-derived cells) or T cells (thymus gland-derived cells).Lymphatic vessels begin as tiny tubes and lead to larger lymphatic ducts and branches until they drain into two ducts in the neck, where the fluid re-enters the bloodstream.Along the way, the fluid passes through lymph nodes, oval structures composed of lymph vessels, connective tissue, and white blood cells. Here, the lymphocytes are either filtered out or added to the contents of the node. Both leukemia and lymphomas (Hodgkin ' s disease and non-Hodgkin ' s lymphomas) are cancers of lymphocytes. The difference is that leukemia starts in the bone marrow while lymphomas originate in lymph nodes and then spread to the bone marrow or other organs.
In the lymph node, lymphocytes receive their initial exposure to foreign substances (antigens), such as bacteria or other microorganisms, activating the lymphocytes to perform their immune functions. The size of a lymph node varies generally from that of a pinhead to a bean. Most nodes are in clusters located throughout the system. Important node clusters are found in the neck, lower arm, armpit, and groin.The tonsils and adenoids are secondary organs composed of masses of lymph tissue that also play a role in the lymphatic system. The spleen is another important organ that processes lymphocytes from incoming blood.
B cells fight infection by producing antibodies that neutralize foreign invaders. Most non-Hodgkin's lymphoma arises from B cells. Common types of B-cell lymphoma include[6]
Types of B-cell lymphoma | Explanation |
Diffuse Large B-Cell Lymphoma (DLBLC). | DLBCL is the most common type of non-Hodgkin ' s lymphoma, accounting for about 30% of all NHL cases. It is an aggressive, fast-growing lymphoma that usually affects adults but can also occur in children. DLBCL can occur in lymph nodes or in organs outside of the lymphatic system. DLBCL includes several subtypes such as mediastinal large B-cell lymphoma, intravascular large B-cell lymphoma, and primary effusion lymphoma. |
Follicular Lymphoma (FLs) | Follicular lymphoma is the second most common type lymphoma, accounting for about 20% of all NHL cases. It is usually indolent (slow growing) but about half of follicular lymphomas transform over time into the aggressive diffuse large B-cell lymphoma. |
Mantle Cell Lymphoma | Mantle cell lymphoma is an aggressive type of lymphoma that represent about 7% of NHL cases. It is a difficult type of lymphoma to treat and often does not respond to chemotherapy. It is found in lymph nodes, the spleen, bone marrow, and gastrointestinal system. Mantle cell lymphoma usually develops in men over age 60. |
Small Lymphocytic Lymphoma (SLL). | SLL is an indolent type of lymphoma that is closely related to B-cell chronic lymphocytic leukemia (CLL). It accounts for about 5% of NHL cases. |
Marginal Zone Lymphomas (MZL). | MZLs are categorized depending on where the lymphoma is located. Mucosa-associated lymphoid tissue lymphomas (MALT) usually involve the gastrointestinal tract, thyroid, lungs, saliva glands, or skin. MALT is often associated with a history of an autoimmune disorder (such as Sjogren syndrome in the salivary glands or Hashimoto's thyroiditis in the thyroid gland). MALT is also associated with bacterial infection in the stomach (H. pylori ) and can be potentially cured by antibiotics when treated in its early stages. Splenic marginal zone lymphoma affects the spleen, blood, and bone marrow. Nodal marginal zone B-cell lymphoma is a rare type of indolent lymphoma that involves the lymph nodes. |
Lymphoplasmacytic Lymphoma. | Lymphoplasmacytic lymphoma, also called Waldenstrom's macroglobulinemia or immunocytoma, is a rare type of lymphoma accounting for about 1% of NHL cases. It usually affects older adults and most often involves bone marrow, lymph nodes, and spleen. |
Primary Central Nervous System Lymphoma. | This lymphoma involves the brain and spinal cord. Although it is generally rare, it is common in people who have AIDS. |
Burkitt's Lymphoma. | This is one of the most common types of childhood NHL, accounting for about 40% of NHL pediatric cases in the United States. It usually starts in the abdomen and spreads to other organs, including the brain. In African children, it often involves facial bones and is associated with Epstein-Barr infection. |
Lymphoblastic Lymphoma. | This lymphoma is also common in children, accounting for about 25% of NHL pediatric cases, most often boys. It is associated with a large mediastinal mass (occurring in chest cavity between the lungs) and carries a high risk for spreading to bone marrow, the brain, and other lymph nodes. |
T cells are involved in killing foreign invaders directly. Non-Hodgkin's lymphoma occurs less often in T cells.[7] Common types of T-cell lymphoma include:
Types of T-cell lymphoma | Explanation |
Peripheral T-cell lymphoma not otherwise specified (PTCL-NOS) | The most common subtype of PTCL. It accounts for approximately 25 percent of all T-cell lymphomas. These lymphomas are often aggressive (fast-growing) and may show up in lymph nodes, skin or other organs of the body. |
Anaplastic large cell lymphoma | This describe several types of T-cell lymphoma and accounts for approximately 12 percent to 15 percent of all T-cell lymphomas in adults and between 10 percent and 30 percent of all lymphomas in children. It can be divided into three types: two systemic (presents in lymph nodes or organs) subtypes — termed ALK positive or ALK negative anaplastic large cell lymphoma, depending on the presence or absence of the ALK protein on the surface of the lymphoma cells — or a skin only type called primary cutaneous anaplastic large cell lymphoma. The systemic types are usually fast-growing while the skin only type is usually more slow-growing. |
Angioimmunoblastic lymphoma | It is a fast-growing T-cell lymphoma accounting for 15 percent to 18 percent of all T-cell lymphomas in the United States. It often presents with swollen lymph nodes and systemic symptoms such as fever and rash. It is generally treated like other fast-growing T-cell lymphomas, but can be manged with milder therapies in certain circumstances. |
Cutaneous T-cell lymphoma | It accounts for 2 percent to 3 percent of all NHL cases and mostly affects adults. The term cutaneous T-cell lymphoma describes a group of typically slow-growing cancers that start, and are most often confined, to the skin. Mycosis fungoides is the most common type of cutaneous T-cell lymphoma. It appears as skin patches or plaques, and is often controlled over many years. Less common forms include Sezary syndrome, primary cutaneous anaplastic large cell lymphoma and lymphomatoid papulosis among others. |
