This is a medical question of type : exams and tests 
 How to diagnose Childhood Hodgkin Lymphoma ? 
 Tests that examine the lymph system are used to detect (find) and diagnose childhood Hodgkin lymphoma. The following tests and procedures may be used:         -   Physical exam and history : An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken.    -   CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the neck, chest, abdomen, or pelvis, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.     -   PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do. Sometimes a PET scan and a CT scan are done at the same time. If there is any cancer, this increases the chance that it will be found.    -   Chest x-ray : An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.    -   Complete blood count (CBC): A procedure in which a sample of blood is drawn and checked for the following:               - The number of red blood cells, white blood cells, and platelets.      - The amount of hemoglobin (the protein that carries oxygen) in the red blood cells.      - The portion of the blood sample made up of red blood cells.              -   Blood chemistry studies : A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease.    -   Sedimentation rate : A procedure in which a sample of blood is drawn and checked for the rate at which the red blood cells settle to the bottom of the test tube. The sedimentation rate is a measure of how much inflammation is in the body. A higher than normal sedimentation rate may be a sign of lymphoma. Also called erythrocyte sedimentation rate, sed rate, or ESR.    -   Lymph node biopsy : The removal of all or part of a lymph node. The lymph node may be removed during an image-guided CT scan or a thoracoscopy, mediastinoscopy, or laparoscopy. One of the following types of biopsies may be done:                -  Excisional biopsy : The removal of an entire lymph node.       -  Incisional biopsy : The removal of part of a lymph node.      -  Core biopsy : The removal of tissue from a lymph node using a wide needle.      -  Fine-needle aspiration (FNA) biopsy : The removal of tissue from a lymph node using a thin needle.          A pathologist views the tissue under a microscope to look for cancer cells, especially Reed-Sternberg cells. Reed-Sternberg cells are common in classical Hodgkin lymphoma. The following test may be done on tissue that was removed:               -  Immunophenotyping : A laboratory test used to identify cells, based on the types of antigens or markers on the surface of the cell. This test is used to diagnose the specific type of lymphoma by comparing the cancer cells to normal cells of the immune system.