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What is childhood non-Hodgkin lymphoma?
Non-Hodgkin lymphoma (NHL) 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. It is made up of a network of lymph vessels, lymph nodes and the lymphatic organs. Lymph vessels carry lymph fluid, which contains lymphocytes and other white blood cells, antibodies and nutrients. Lymph nodes sit along the lymph vessels and filter lymph fluid. The lymphatic organs include the spleen, thymus, tonsils, adenoids and bone marrow.
Lymphocytes develop in the bone marrow from precursor cells called stem cells. Stem cells develop into different types of cells that have different jobs. Lymphocytes are types of white blood cells that help fight infection. There are 2 types of lymphocytes:
- B cells stay in the bone marrow until they mature.
- T cells move to the thymus to mature.
Lymphocytes sometimes change and no longer grow or behave normally. These abnormal cells can form tumours called lymphomas. NHL can start from either B cells or T cells. The 4 main types of childhood NHL are:
- Burkitt lymphoma including Burkitt-like lymphoma
- lymphoblastic lymphoma (usually called lymphocytic lymphoma in adults)
- diffuse large B-cell lymphoma (includes primary mediastinal B-cell lymphoma)
- anaplastic large cell lymphoma
Rare types of NHL can also develop. Post-transplant lymphoproliferative disease (PTLD) is a rare form of NHL that may occur after a solid organ transplant. Follicular NHL and marginal zone B-cell lymphoma are extremely rare in childhood.
The different types of NHL look different under a microscope. They also develop and grow differently. Most types of childhood NHL are high grade because they grow and spread quickly. Your child’s doctor will find out the type of NHL to make sure your child gets the treatment that works best for that type.
Because lymphocytes are found throughout the lymphatic system, childhood NHL can start almost anywhere in the body. It usually starts in a group of lymph nodes in one part of the body, such as in the neck, above the collarbone, or in the chest, abdomen or groin. Children may also have large spleens when they are diagnosed. Childhood NHL doesn’t spread in a predictable way. It can spread through the lymphatic system or the blood to almost any tissue or organ in the body.
The other main form of cancer of the lymphatic system that is seen in children and teens is Hodgkin lymphoma (HL). The abnormal B cells of Hodgkin lymphoma look and behave differently from non-Hodgkin lymphoma cells. Hodgkin lymphomas and non-Hodgkin lymphomas are treated differently.