Laboratory tests performed to diagnose and classify leukemia
- By:groshan fabiola
A doctor- a pathologist or a hematologist/oncologist- having special training in recognizing cells from blood and lymphoid tissue diseases will examine under the microscope all bone marrow aspirates and biopsy specimens, all lymph node biopsy specimens, all CSF specimens, and any blood smears with significant abnormalities.After cells from a sample are placed on glass microscope slides, there can follow the cytochemistry. The cells are stained with dyes that are attracted to certain chemicals that are present only in some types of leukemia cells.
The technique called flow cytometry can be used to examine the cells from bone marrow, lymph nodes, and blood samples. It can determine the exact type of leukemia very accurately. The cells that are being examined using this technique are treated with selected antibodies, and passed in front of a laser beam. Each antibody sticks to certain types of leukemia cells, and if those cells are present, the laser will cause them to give off light, and the computer will measure and analyze it. There can be used this test in order to estimate the amount of DNA in the leukemia cells as well.In immunocytochemistry, cells from the bone marrow aspiration or biopsy sample are treated with special laboratory antibodies, and then the sample is treated in that way that certain types of cells change color. Under a microscope, there can be seen the change of color.There are some types of leukemia that have an abnormal number of chromosomes. Cytogenetics detects if part of one chromosome may be attached to part of a different chromosome. This change is called a translocation and can be seen usually under a microscope.
We must mention the fact that there are certain substances called antigen receptors which occur on the surface of lymphocytes, and have an important role in initiating a response from the immune system. Normally, there are many different antigen receptors in normal lymphoid cells, but in lymphocytic leukemias, all the cells have the same antigen receptor.
Most translocations that are visible under a microscope in cytogenetic tests can be detected by tests of leukemia cell DNA as well. Some translocations involving parts of chromosomes too small to be seen with usual cytogenetic testing under a microscope can be seen with the help of DNA tests like polymerase chain reaction or fluorescent in situ hybridization.In order to diagnose and evaluate a child with leukemia there are frequently used a chest x-ray and bone x-ray. Tests using sound waves are useful to determine if the leukemia involves the kidney, spleen, or liver.There can be also used a computer tomography, in which a X-ray beam moves around the body, taking pictures from different angles. Magnetic resonance imaging is a procedure that uses large magnets and radio waves and produces computer-generated pictures of internal organs; Gallium scan and bone scan is a procedure in which a radioactive chemical is injected and accumulates in areas of cancer or infection in the body. This area can be viewed with a special camera.About the author:
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