Non-Hodgkin lymphoma is a cancer that starts in lymphocytes. Lymphocytes are cells of the lymphatic system. The lymphatic system works with other parts of your immune system to help your body fight infection and disease. The lymphatic system is made up of a network of lymph vessels (which carry lymph fluid), lymph nodes and the lymphatic organs (such as the spleen, thymus, tonsils and bone marrow).
Lymphocytes are special white blood cells that help fight infection. They develop in the bone marrow from immature cells (called stem cells). There are 2 types of lymphocytes:
- B cells stay in the bone marrow or lymphatic organs until they mature.
- T cells move to the thymus gland to mature.
Lymph fluid is a clear yellowish fluid that contains lymphocytes. Lymph vessels collect lymph fluid from different tissues throughout the body, filter it through the lymph nodes and return it to the bloodstream. Lymph nodes are small bean-shaped glands. Clusters of lymph nodes are found in your neck, underarms, chest, abdomen and groin. As lymph fluid passes through the lymph nodes, they filter out waste, bacteria and unwanted cells, including cancer cells.
Non-Hodgkin lymphoma develops when a lymphocyte, either a B cell or T cell, becomes abnormal. It can begin in almost any part of the body and can form tumours. It usually starts in a group of lymph nodes in one part of the body, most often the neck. Eventually, it can spread to almost any tissue or organ in the body through the lymphatic system or the bloodstream.
There are over 30 types of non-Hodgkin lymphoma. The cells of the different types look different under a microscope, and they develop and spread differently (for example, slowly or aggressively). The way the cancer cells develop and spread depends on the type of lymphocyte that became abnormal. Most types of non-Hodgkin lymphoma develop from B cells. Your doctor will find out which type of non-Hodgkin lymphoma you have to make sure you get the treatment that works best for that type.
