Malignant Lymphoma Health Article

Definition

Lymphomas are a group of cancers in which cells of the lymphatic system become abnormal and start to grow uncontrollably. Because there is lymph tissue in many parts of the body, lymphomas can start in almost any organ of the body.

Description

The lymphatic system is made up of ducts or tubules that carry lymph to all parts of the body. Lymph is a milky fluid that contains lymphocytes. These, along with monocytes and granulocytes make up the leukocytes, or white blood cells, the infection-fighting and reparative bodies in the blood. Small pea-shaped organs found along the network of lymph vessels are called lymph nodes; their main function is to make and store lymphocytes. Clusters of lymph nodes are found in the pelvic region, underarm, neck, chest, and abdomen. The spleen (an organ in the upper abdomen), the tonsils, and the thymus (a small organ beneath the breastbone) are also part of the lymphatic system. Lymphocytes are held within the lymphoid tissue until they join the flow of lymph through the node. There are two main types of lymphocytes: the T cell and the B cell. Lymphomas develop from these two types. B-cell lymphomas are more common among adults, while among children, the incidence of T- and B-cell lymphomas are almost equal.

The T and the B cells perform different jobs within the immune system. When an infectious bacterium enters the body, the B cells make proteins called antibodies, which attach themselves to the bacteria, and flag them for destruction by other immune cells. The T cells help protect the body against viruses. When a virus enters a cell, it generally produces certain proteins that it projects onto the surface of the infected cell. T cells recognize these proteins and produce cytokines to destroy the infected cells. Some cytokines attract other cell types, which can digest the virus-infected cell. T cells can also destroy some types of cancer cells.

Lymphomas can be divided into two main types: Hodgkin's and non-Hodgkin's. There are at least 10 types of non-Hodgkin's lymphomas that are grouped (staged) by how aggressively they grow: slow growing (low grade), intermediate growing, and rapidly growing (high grade); and how far they spread.

Most non-Hodgkin's lymphomas begin in the lymph nodes; about 20% start in other organs, such as the lungs, liver or gastrointestinal tract. When lymphomas begin, malignant lymphocytes multiply uncontrollably and do not perform their normal functions, which affects the body's ability to fight infections. In addition, malignant cells may crowd the bone marrow, and, depending on the stage, prevent the production of normal red blood cells, white blood cells, and platelets. A low red blood cell count causes anemia, while a reduction in the number of platelets makes the person susceptible to excessive bleeding. Cancerous cells can also invade other organs through the circulatory system of the lymph, causing those organs to malfunction.