Tests that examine the blood and bone marrow are used to detect (find) and diagnose childhood AML, childhood CML, JMML, and MDS. 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 patients health habits and past illnesses and treatments will also be taken.     -   Complete blood count (CBC) with differential: A procedure in which a sample of blood is drawn and checked for the following:                -  The number of red blood cells and platelets.      - The number and type of white blood cells.      - 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.              -   Peripheral blood smear : A procedure in which a sample of blood is checked for blast cells, the number and kinds of white blood cells, number of platelets, and changes in the shape of the 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.    -   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.    -   Biopsy : The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. Biopsies that may be done include the following:               -  Bone marrow aspiration and biopsy : The removal of bone marrow, blood, and a small piece of bone by inserting a hollow needle into the hipbone or breastbone.      -  Tumor biopsy: A biopsy of a chloroma may be done.      -  Lymph node biopsy: The removal of all or part of a lymph node.               -   Cytogenetic analysis : A laboratory test in which cells in a sample of blood or bone marrow are viewed under a microscope to look for certain changes in the chromosomes. Changes in the chromosomes may include when part of one chromosome is switched with part of another chromosome, part of one chromosome is missing or repeated, or part of one chromosome is turned upside down. The following test is a type of cytogenetic analysis:               -  FISH (fluorescence in situ hybridization): A laboratory technique used to look at genes or chromosomes in cells and tissues. Pieces of DNA that contain a fluorescent dye are made in the laboratory and added to cells or tissues on a glass slide. When these pieces of DNA bind to specific genes or areas of chromosomes on the slide, they light up when viewed under a microscope with a special light.             -   Reverse transcriptionpolymerase chain reaction (RTPCR) test: A laboratory test in which cells in a sample of tissue are studied using chemicals to look for certain changes in the structure or function of genes.    -   Immunophenotyping : A process used to identify cells, based on the types of antigens or markers on the surface of the cell, that may include special staining of the blood and bone marrow cells. This process is used to diagnose the subtype of AML by comparing the cancer cells to normal cells of the immune system.    -   Molecular testing : A laboratory test to check for certain genes, proteins, or other molecules in a sample of blood or bone marrow. Molecular tests also check for certain changes in a gene or chromosome that may cause or affect the chance of developing AML. A molecular test may be used to help plan treatment, find out how well treatment is working, or make a prognosis.    -   Lumbar puncture : A procedure used to collect a sample of cerebrospinal fluid (CSF) from the spinal column. This is done by placing a needle between two bones in the spine and into the CSF around the spinal cord and removing a sample of the fluid. The sample of CSF is checked under a microscope for signs that leukemia cells have spread to the brain and spinal cord. This procedure is also called an LP or spinal tap.