This is a medical question of type : information 
 What is (are) Childhood Non-Hodgkin Lymphoma ? 
 Key Points
                    - Childhood non-Hodgkin lymphoma is a disease in which malignant (cancer) cells form in the lymph system.    - The main types of lymphoma are Hodgkin lymphoma and non-Hodgkin lymphoma.    - There are three major types of childhood non-Hodgkin lymphoma.         - Mature B-cell non-Hodgkin lymphoma     - Lymphoblastic lymphoma     - Anaplastic large cell lymphoma        - Some types of non-Hodgkin lymphoma are rare in children.    - Past treatment for cancer and having a weakened immune system affect the risk of having childhood non-Hodgkin lymphoma.    - Signs of childhood non-Hodgkin lymphoma include breathing problems and swollen lymph nodes.    - Tests that examine the body and lymph system are used to detect (find) and diagnose childhood non-Hodgkin lymphoma.    - A biopsy is done to diagnose childhood non-Hodgkin lymphoma.    - Certain factors affect prognosis (chance of recovery) and treatment options.
                
                
                    Childhood non-Hodgkin lymphoma is a disease in which malignant (cancer) cells form in the lymph system.
                    Childhood non-Hodgkin lymphoma is a type of cancer that forms in the lymph system, which is part of the body's immune system. The immune system protects the body from foreign substances, infection, and diseases. The lymph system is made up of the following:         -  Lymph: Colorless, watery fluid that carries white blood cells called lymphocytes through the lymph system. Lymphocytes protect the body against infections and the growth of tumors. There are three types of lymphocytes:               -  B lymphocytes that make antibodies to help fight infection.      -  T lymphocytes that help B lymphocytes make the antibodies that help fight infection.      -  Natural killer cells that attack cancer cells and viruses.             -  Lymph vessels: A network of thin tubes that collect lymph from different parts of the body and return it to the bloodstream.    -  Lymph nodes: Small, bean-shaped structures that filter lymph and store white blood cells that help fight infection and disease. Lymph nodes are located along the network of lymph vessels found throughout the body. Clusters of lymph nodes are found in the neck, underarm, abdomen, pelvis, and groin.     -  Spleen: An organ that makes lymphocytes, filters the blood, stores blood cells, and destroys old blood cells. The spleen is on the left side of the abdomen near the stomach.    -  Thymus: An organ in which lymphocytes grow and multiply. The thymus is in the chest behind the breastbone.    -  Tonsils: Two small masses of lymph tissue at the back of the throat. The tonsils make lymphocytes.    -  Bone marrow: The soft, spongy tissue in the center of large bones. Bone marrow makes white blood cells, red blood cells, and platelets.         Non-Hodgkin lymphoma can begin in B lymphocytes, T lymphocytes, or natural killer cells. Lymphocytes can also be found in the blood and collect in the lymph nodes, spleen, and thymus.   Lymph tissue is also found in other parts of the body such as the stomach, thyroid gland, brain, and skin.   Non-Hodgkin lymphoma can occur in both adults and children. Treatment for children is different than treatment for adults. See the following PDQ summaries for information about treatment of non-Hodgkin lymphoma in adults:         -  Adult Non-Hodgkin Lymphoma     -  Primary CNS Lymphoma Treatment     -  Mycosis Fungoides and the Sezary Syndrome Treatment
                
                
                    The main types of lymphoma are Hodgkin lymphoma and non-Hodgkin lymphoma.
                    Lymphomas are divided into two general types: Hodgkin lymphoma and non-Hodgkin lymphoma. This summary is about the treatment of childhood non-Hodgkin lymphoma. See the PDQ summary on Childhood Hodgkin Lymphoma Treatment for information about childhood Hodgkin lymphoma.
                
                
                    There are three major types of childhood non-Hodgkin lymphoma.
                    The type of lymphoma is determined by how the cells look under a microscope. The three major types of childhood non-Hodgkin lymphoma are:     Mature B-cell non-Hodgkin lymphoma    Mature B-cell non-Hodgkin lymphomas include:            -  Burkitt and Burkitt-like lymphoma/leukemia: Burkitt lymphoma and Burkitt leukemia are different forms of the same disease. Burkitt lymphoma/leukemia is an aggressive (fast-growing) disorder of B lymphocytes that is most common in children and young adults. It may form in the abdomen, Waldeyer's ring, testicles, bone, bone marrow, skin, or central nervous system (CNS). Burkitt leukemia may start in the lymph nodes as Burkitt lymphoma and then spread to the blood and bone marrow, or it may start in the blood and bone marrow without forming in the lymph nodes first. Both Burkitt leukemia and Burkitt lymphoma have been linked to infection with the Epstein-Barr virus (EBV), although EBV infection is more likely to occur in patients in Africa than in the United States. Burkitt and Burkitt-like lymphoma/leukemia are diagnosed when a sample of tissue is checked and a certain change to the c-myc gene is found.     -   Diffuse large B-cell lymphoma: Diffuse large B-cell lymphoma is the most common type of non-Hodgkin lymphoma. It is a type of B-cell non-Hodgkin lymphoma that grows quickly in the lymph nodes. The spleen, liver, bone marrow, or other organs are also often affected. Diffuse large B-cell lymphoma occurs more often in adolescents than in children.     -   Primary mediastinal B-cell lymphoma: A type of lymphoma that develops from B cells in the mediastinum (the area behind the breastbone). It may spread to nearby organs including the lungs and the sac around the heart. It may also spread to lymph nodes and distant organs including the kidneys. In children and adolescents, primary mediastinal B-cell lymphoma occurs more often in older adolescents.              Lymphoblastic lymphoma     Lymphoblastic lymphoma is a type of lymphoma that mainly affects T-cell lymphocytes. It usually forms in the mediastinum (the area behind the breastbone). This causes trouble breathing, wheezing, trouble swallowing, or swelling of the head and neck. It may spread to lymph nodes, bone, bone marrow, skin, the CNS, abdominal organs, and other areas. Lymphoblastic lymphoma is a lot like acute lymphoblastic leukemia (ALL).       Anaplastic large cell lymphoma     Anaplastic large cell lymphoma is a type of lymphoma that mainly affects T-cell lymphocytes. It usually forms in the lymph nodes, skin, or bone, and sometimes forms in the gastrointestinal tract, lung, tissue that covers the lungs, and muscle. Patients with anaplastic large cell lymphoma have a receptor, called CD30, on the surface of their T cells. In many children, anaplastic large cell lymphoma is marked by changes in the  ALK  gene that makes a protein called anaplastic lymphoma kinase. A pathologist checks for these cell and gene changes to help diagnose anaplastic large cell lymphoma.
                
                
                    Some types of non-Hodgkin lymphoma are rare in children.
                    Some types of childhood non-Hodgkin lymphoma are less common. These include:         -  Pediatric-type follicular lymphoma : In children, follicular lymphoma occurs mainly in males. It is more likely to be found in one area and does not spread to other places in the body. It usually forms in the tonsils and lymph nodes in the neck, but may also form in the testicles, kidney, gastrointestinal tract, and salivary gland.    -   Marginal zone lymphoma : Marginal zone lymphoma is a type of lymphoma that tends to grow and spread slowly and is usually found at an early stage. It may be found in the lymph nodes or in areas outside the lymph nodes. Marginal zone lymphoma found outside the lymph nodes in children is called mucosa-associated lymphoid tissue (MALT) lymphoma and may be linked to  Helicobacter pylori  infection of the gastrointestinal tract and  Chlamydophila psittaci  infection of the conjunctival membrane which lines the eye.    -   Primary central nervous system (CNS) lymphoma : Primary CNS lymphoma is extremely rare in children.    -   Peripheral T-cell lymphoma : Peripheral T-cell lymphoma is an aggressive (fast-growing) non-Hodgkin lymphoma that begins in mature T lymphocytes. The T lymphocytes mature in the thymus gland and travel to other parts of the lymph system, such as the lymph nodes, bone marrow, and spleen.    -   Cutaneous T-cell lymphoma : Cutaneous T-cell lymphoma begins in the skin and can cause the skin to thicken or form a tumor. It is very rare in children, but is more common in adolescents and young adults. There are different types of cutaneous T-cell lymphoma, such as cutaneous anaplastic large cell lymphoma, subcutaneous panniculitis-like T-cell lymphoma, gamma-delta T-cell lymphoma, and mycosis fungoides. Mycosis fungoides rarely occurs in children and adolescents.
                
                
                    Past treatment for cancer and having a weakened immune system affect the risk of having childhood non-Hodgkin lymphoma.
                    Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesnt mean that you will not get cancer. Talk with your child's doctor if you think your child may be at risk.    Possible risk factors for childhood non-Hodgkin lymphoma include the following:         - Past treatment for cancer.    - Being infected with the Epstein-Barr virus or human immunodeficiency virus (HIV).    - Having a weakened immune system after a transplant or from medicines given after a transplant.    - Having certain inherited diseases of the immune system.        If lymphoma or lymphoproliferative disease is linked to a weakened immune system from certain inherited diseases, HIV infection, a transplant or medicines given after a transplant, the condition is called lymphoproliferative disease associated with immunodeficiency. The different types of lymphoproliferative disease associated with immunodeficiency include:         - Lymphoproliferative disease associated with primary immunodeficiency.    - HIV-associated non-Hodgkin lymphoma.    -  Post-transplant lymphoproliferative disease.