Table of Contents Table of Contents
Previous Page  21 / 94 Next Page
Information
Show Menu
Previous Page 21 / 94 Next Page
Page Background

19

NCCN Guidelines for Patients

®

:

Acute Lymphoblastic Leukemia, Version 1.2017

2

Testing for ALL

Genetic tests

Cell assessment

At the lab, a pathologist will look at the cells in a

blood or bone marrow sample with a microscope.

This test is simply called cell assessment. Doctors

may also refer to this test as a morphologic

assessment. Special dyes may be used to stain the

sample. This helps to show the differences between

parts of a single cell and between many cells.

The pathologist will look at the size, shape, type,

and other features of the cells in the blood or bone

marrow sample. This is to see if the cells look more

like normal, mature cells or more like abnormal,

immature cells. The number of very immature cells—

blast cells—in the sample is important.

Normally, there are no blast cells in the blood. And,

in a healthy person, blast cells make up no more

than 5% of cells in the bone marrow. This means

that no more than 5 out of every 100 cells in the

bone marrow are blast cells. In a person with ALL,

blast cells make up 25% or more of cells in the bone

marrow. This means that at least 25 out of every 100

cells are blast cells.

Flow cytometry

Flow cytometry is used to identify and count types

of cells in a sample. It can show if cells are normal

or abnormal. It can also tell the difference between

types of leukemia cells. This test is used to help

confirm ALL and find out the type of lymphocytes in

which it started. Flow cytometry is also used to check

treatment results.

ALL cells have a common pattern or “signature” of

proteins. The type and pattern of proteins differs

based on the type of maturity of the cell. The pattern

of surface proteins is called the immunophenotype.

Flow cytometry can identify the type of leukemia cells

present based on the pattern of surface proteins.

This is called immunophenotyping. A sample of bone

marrow is often used for immunophenotyping, but a

blood sample may also be used.

Flow cytometry involves first adding a marker—a

light-sensitive dye—to cells. The marker reacts with

surface proteins found only on certain types of cells.

The cells are then passed through a flow cytometry

machine. The machine identifies leukemia cells

based on the pattern of surface proteins. It can also

count the number of leukemia cells present. This is

helpful for checking treatment results.

Flow cytometry is sometimes used to measure the

amount of DNA in the leukemia cells. In such cases,

a marker that reacts with DNA is used. The amount

of DNA reflects the number of chromosomes in the

cells. This can help to show if the cells have too

many or too few chromosomes.

Genetic tests

Cytogenetic testing

Cytogenetic testing uses a microscope to examine

the chromosomes inside cells. This type of test

is used to look for abnormal changes in the

chromosomes of the leukemia cells. It is often done

on a sample of bone marrow. It can also be done on

a sample of blood.

Certain chromosome changes in the leukemia cells

can affect treatment options and outlook. Thus, this

is a key test that is used to help plan treatment for

ALL. This test is given along with other initial tests

when ALL is first diagnosed. It may also be repeated

to check treatment results.

For this test, a pathologist will look at a “map” of

the chromosomes under a microscope. This map

is called a karyotype. It will show if there are any

abnormal changes in the size, shape, structure, or

number of chromosomes. This test can also be used

to count the number of leukemia cells.