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.
