AML Leukemia Diagnosis

How is Acute Myelogenous Leukemia (AML) Diagnosed?

Signs and Symptoms of Acute Myelogenous Leukemia

Acute myelogenous leukemia can cause many different signs and symptoms. Most of these occur in all kinds of AML, but some are particularly common with certain subtypes.

Patients with AML often have several generalized symptoms. These can include weight loss, unusual fatigue, fever, and loss of appetite. Of course, these are not specific to AML and are more often caused by something other than cancer.

Most signs and symptoms of AML result from a shortage of normal blood cells due to crowding out of normal blood cell-producing bone marrow by the leukemia cells. As a result, people do not have enough properly functioning red blood cells, white blood cells, and blood platelets.

Anemia, a shortage of red blood cells, causes shortness of breath, excessive tiredness, and a pale color to the skin.

A shortage of normal white blood cells (leukopenia), and, in particular, too few mature granulocytes (called neutropenia or granulocytopenia), increases the risk of infections. Although leukemia is often a cancer of white blood cells and patients with leukemia may have very high white blood cell counts (leukocytosis), the abnormal leukemia cells do not protect against infection.

Thrombocytopenia (not having enough platelets needed for plugging holes in damaged blood vessels) can lead to excessive bruising, bleeding, frequent or severe nosebleeds, and bleeding from the gums.

When leukemia cells spread outside the bone marrow, it is called extramedullary spread. This may occur after AML has been diagnosed.. Less often, extramedullary spread may be the first sign of cancer in someone who has not yet been diagnosed with AML.

If leukemia cells spread to the skin, it can cause small pigmented (colored) spots that look like common rashes. A tumor-like collection of AML cells under the skin or other parts of the body is called a chloroma or granulocytic sarcoma.

Acute myelogenous leukemia sometimes causes enlargement of the liver and spleen, two organs located on the right and left side respectively, of the abdomen. Enlargement of these organs would be noticed as a fullness, or even swelling, of the belly. These organs are usually covered by the lower ribs but when enlarged, they can be felt by the doctor examining the patient.

Acute myelogenous leukemia may occasionally spread to lymph nodes. If the affected nodes are close to the surface of the body (lymph nodes on the sides of the neck, in the groin, underarm areas, above the collarbone, etc.), a person or the health care provider may notice the swelling.

Leukemia cells that spread into the brain and spinal cord (central nervous system, or CNS) can cause headache, weakness, seizures, vomiting, difficulty in maintaining balance, and blurred vision. This is not common in patients with AML.

Some patients have bone pain or joint pain caused by the spread of leukemic cells to the surface of the bone or into the joint from the marrow cavity. Other uncommon sites of extramedullary spread include the testicles, ovaries, kidneys, or tissues around the eyes.

A particular subtype of AML known as the M5 or monocytic form may spread to the gums, causing swelling, pain, and bleeding.

Types of Specimens Used to Diagnose and Evaluate Acute Myelogenous Leukemia

If signs and symptoms suggest that a patient has leukemia, the doctor will need to check samples of cells from the patient's blood and bone marrow to be sure of the diagnosis. Other tissue and cell samples may also be taken in order to guide treatment.

Blood cell counts and blood cell examination: Changes in the numbers of different types of blood cells and the appearance of these cells under the microscope often help diagnose leukemia. Most patients with AML have too many white cells in their blood, not enough red blood cells, and not enough platelets. In addition, many of these white blood cells will be blasts, an immature blood-forming cell normally found only in the bone marrow. These immature cells do not function normally. Even though these findings suggest leukemia, usually the disease cannot be diagnosed without getting a sample of bone marrow cells.

Bone marrow aspiration and biopsy: The bone marrow sample is taken from the pelvic (hip) bone. The patient lies on his or her side and the doctor feels the bones at the top of the buttocks. The area is cleaned with a special soap. Before the sampling, the doctor injects a local anesthetic, usually lidocaine, into the back of the pelvic bone about an inch or two from the middle of the back. This causes some very brief stinging. In some cases, the patient can choose to receive other medicines to reduce pain during the procedure. Once this has had a few moments to take effect, the doctor makes a small cut so he or she can insert a needle, which is about half as wide as a pencil and has a handle on one end that the doctor holds while moving it into the bone. The needle is moved through the bone with a twisting motion.

In bone marrow aspiration, a syringe is used to suck out a small amount of liquid bone marrow (about 1 teaspoon). Sometimes the needle going into the bone is painful, but it only lasts a short time. The removal of bone marrow is often painful or at least uncomfortable for a brief moment.

Usually this is followed by a bone marrow biopsy in the same area. The doctor carefully moves the needle further into the bone marrow to collect a second sample called a core biopsy. This contains a small solid piece of bone and marrow (about 1/16-inch in diameter and 1/2-inch long) and is removed with a slightly larger needle. You may also feel some pressure as the doctor removes the marrow specimen. After the biopsy needle is pulled out, this solid sample is pushed out of the needle with a wire so that it can be examined under a microscope. You will have pressure held against your buttock at the biopsy site for a few minutes and a pressure dressing applied to help prevent bleeding. this is especially important for patients who might bleed more because of low platelet counts.

These bone marrow tests are used to diagnose leukemia and, later, to tell if the leukemia is responding to treatment.

Blood chemistry tests: These tests measure the amounts of certain chemicals in the blood but are not used to diagnose leukemia. In patients already known to have leukemia, these tests help detect liver or kidney problems due to damage caused by the spread of leukemic cells or from the side effects of certain chemotherapy drugs. These tests also help determine whether treatment is needed to correct abnormally low or high blood levels of certain minerals.

Lumbar puncture (spinal tap): In this procedure, a small needle is placed into the spinal cavity in the lower back (below the level of the spinal cord) to withdraw cerebrospinal fluid (CSF) to be examined for leukemia cells. This is not routinely done for patients with AML.

Lab Tests Used to Diagnose and Classify Acute Myelogenous Leukemia

One or more of the following lab tests may be used.

Routine microscopic exam: Any samples taken (blood, bone marrow, or cerebrospinal fluid) are examined under a microscope by a pathologist (doctor specializing in diagnosis of disease by laboratory tests) and are often also reviewed by the patient's hematologist/oncologist (doctor specializing in medical treatment of cancer and blood diseases).

Based on the bone marrow cells’ size, shape, and granules, doctors can classify them into specific types. A key element of this cell classification is whether the cells appear mature (resembling normal cells of circulating blood) or immature (lacking features of normal circulating blood cells). The most immature cells are called blasts.

The percentage of cells in the bone marrow that are blasts is particularly important. Having at least 20% blasts in the marrow is generally required for a diagnosis of acute myelogenous leukemia. IAML (Acute Myelocytic Leukemia Intergroup) can also be diagnosed if the blasts have a chromosome change that occurs only in a specific type of AML, even though the blast percentage doesn’t reach 20%. In order for a patient to be considered to be in remission after treatment, the blast percentage must be no higher than 5%.

Sometimes this examination does not provide a definite answer, and other lab tests are needed.

Cytochemistry: Cytochemistry studies involve placing cells from the sample on glass microscope slides, then exposing them to chemical stains (dyes) that are attracted to or react with only some types of leukemia cells. These stains cause color changes that can be seen only under a microscope. For example, one stain distinguishes AML from acute lymphocytic leukemia (ALL). The stain causes the granules of most AML cells to appear as black spots under the microscope, but it does not cause ALL cells to change colors.

Flow cytometry: This technique is often used to examine the cells from bone marrow and blood samples. It is very accurate in determining the exact type of leukemia.

Leukemia cells can be distinguished by the kinds of molecules on their surface. A sample of cells is treated with special antibodies which stick to the cells only if certain molecules are present on their surfaces. The cells are then passed in front of a laser beam. If the sample contains cells that now have antibodies attached to them, the laser will cause them to give off light, which is measured and analyzed by a computer. Groups of cells can be separated and counted by these methods.

Immunocytochemistry: During this test, as in flow cytometry, cells from the bone marrow aspiration or biopsy sample are treated with special antibodies that react only to certain molecules. But instead of using a laser and computer for analysis, the sample is treated so that certain types of cells change color. The color change can be seen only under a microscope. Like flow cytometry, it is helpful in distinguishing different types of leukemia from one another and from other diseases.

Cytogenetics: These tests involve looking at a cell’s chromosomes under a microscope. Normal human cells contain 46 chromosomes, pieces of DNA that control cell growth and metabolism.

In certain types of leukemia, 2 chromosomes may exchange some of their DNA, so that part of one chromosome becomes attached to part of a different chromosome. This change, called a translocation, can usually be seen under a microscope. Other changes in chromosomes, such as inversions, deletions, or additions, are also possible. Recognizing these changes helps to identify certain types of AML and is important in determining the outlook for the patient.

The testing usually takes about 3 weeks, because the leukemic cells must grow in laboratory dishes for a couple of weeks before their chromosomes are ready to be viewed under the microscope. The results of cytogenetic testing are written in a shorthand form that describes which chromosome changes are present:

• A translocation, written as t(1;2), for example, means a part of chromosome 1 is now located on chromosome 2 and vice versa.
• An inversion, written as inv(16), for example, means that part of the chromosome 16 is upside down and is now in reverse order but is still attached to the chromosome it originated from.
• A deletion, written as del(7) or -7, for example, indicates part of chromosome 7 has been lost.
• An addition, +8, for example, means that all or part of chromosome 8 has been duplicated, and too many copies of it are found within the cell.

Molecular genetic studies: Special tests of leukemia cell DNA can also find most translocations that are visible under a microscope in cytogenetic tests, as well as some translocations too small to be seen with usual cytogenetic testing under a microscope.

This sophisticated testing, called FISH (Fluorescent In Situ Hybridization), is helpful in classifying leukemia because many subtypes of AML have distinctive translocations. Information about these translocations may be useful in predicting how the patient will respond to treatment.

These tests may also be used after treatment to find small numbers of leukemia cells that can be missed under a microscope.

Gene-expression profiling: This is a new experimental technique that is being used for many cancers. It produces a pattern of the genes that are in the cancer cells. This creates a unique fingerprint that can distinguish different kinds of cancer cells. It is also being used to classify subtypes of AML into different risk categories. This will add to the information that comes from the standard molecular genetic studies that only look for specific genetic abnormalities.

Imaging Studies

Imaging studies are ways of producing pictures of the inside of the body. Because leukemia does not usually form visible tumors, imaging tests are of limited value. There are several imaging studies that might be done in people with AML, but they are done more often to look for infections or other problems, rather than for the leukemia itself.

X-rays: Routine chest x-rays may be done if a lung infection is suspected.

Computed tomography (CT) scan: The CT scan is an x-ray procedure that produces detailed cross-sectional images of your body. Instead of taking one picture, as does a conventional x-ray, a CT scanner takes many pictures of the part of your body being studied as it rotates around you. A computer then combines these pictures into an image of a slice of your body.

CT scans are helpful in looking at internal organs. They can spot abscesses (pockets of infection), enlarged organs, and any large accumulation of leukemia cells.

If you are having a CT of the abdomen, after a set of pictures is taken you may be asked to drink 1 or 2 pints of a radiocontrast agent, or dye. This helps outline the intestine so that certain areas are not mistaken for tumors. You may also receive an IV (intravenous) line through which the contrast dye is injected. This helps better outline structures in your body. A second set of pictures is then taken.

The injection can cause some flushing (feeling of warmth, especially in the face). Some people are allergic and get hives; rarely more serious reactions like trouble breathing and low blood pressure can occur. Be sure to tell the doctor if you have ever had a reaction to any contrast material used for x-rays.

CT scans take longer than regular x-rays, and you need to lie still on a table while they are being done. The part of your body being examined is placed within the scanner, a doughnut-shaped machine that completely surrounds the table. The test is painless, but you may find it uncomfortable to hold still in certain positions for minutes at a time.

CT scans can also be used to guide a biopsy needle precisely into a suspected abnormality, such as an abscess. For this procedure, called a CT-guided needle biopsy, you remain on the CT scanning table while a radiologist moves a biopsy needle toward the location of the mass. CT scans are repeated until the doctors are confident that the needle is within the mass. A fine needle biopsy sample (tiny fragment of tissue) or a core needle biopsy sample (a thin cylinder of tissue about 1/2-inch long and less than 1/8-inch in diameter) is then removed and examined under a microscope.

Magnetic resonance imaging (MRI) scans: MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed by tissues in the body and then released in a pattern formed by the type of tissue and by certain diseases. A computer translates the pattern of radio waves given off by the tissues into a very detailed image of parts of the body. Not only does this produce cross-sectional slices of the body like a CT scanner, it can also produce slices that are parallel with the length of your body. A contrast material might be injected just as with CT scans, but is used less often.

MRI scans are very helpful in looking at the brain and spinal cord.

MRI scans are a little more uncomfortable than CT scans. First, they take longer—often up to an hour. Also, you have to be placed inside a tube, which is confining and can upset people with claustrophobia. The machine also makes a thumping noise that you may find disturbing. Some places provide headphones with music to block this out.

Gallium scan and bone scan: For this procedure, the doctor injects a slightly radioactive chemical into the bloodstream that collects in areas of cancer or infection. This accumulation of radioactivity can then be viewed by a special camera. These tests are useful when a patient has bone pain that might be due to infection or cancer.

Ultrasound: This test uses sound waves to produce images of internal organs. The test can distinguish solid from fluid-filled masses. It can help to show whether the kidneys, liver, or spleen are enlarged.

This is an easy test. It uses no radiation, which is why it is often used to look at developing fetuses. For an ultrasound examination, you simply lie on a table, and a technician moves the transducer over the part of your body being examined. Usually the skin is first lubricated with a gel.

American Cancer Society

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If you or a loved one have been diagnosed with any of the following leukemia's, then please contact us immediately:

• Aplastic Anemia (AA)
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• Myelodysplastic Syndrome (MDS)
• Non-Hodgkin's Lymphoma (NHL)

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