How is childhood leukemia found?

At this time, there are no special tests advised to help find leukemia early. The best way to find the disease early is for the parents to call the doctor right away if they notice that their child has any of the symptoms listed below.

Careful, regular medical checkups are important for children who have been treated with chemotherapy (chemo) or radiation therapy for an earlier cancer, children who have certain genetic conditions (such as Li-Fraumeni syndrome or Down syndrome), and children who have had organ transplants. These children are at greater risk for certain types of leukemia.

Childhood leukemia is often found because a child has symptoms that prompt a visit to the doctor. The exams and tests below are used to find the disease, measure how advanced it may be, and help decide what type of leukemia it is. That way, treatment can be tailored to provide the best chance of success.

Signs and symptoms of childhood leukemia

Most of the signs and symptoms of leukemia result from a lack of normal blood cells. This happens because the cancer cells crowd out the normal cells that make blood in the bone marrow. The leukemia cells may spread to other parts of the body, which can also cause symptoms.

Keep in mind that many of the symptoms listed here are most often caused by other problems – not leukemia. Still, it's important to let your child's doctor know about them so that the cause can be found and treated, if needed.

Tiredness (fatigue) and pale skin: A child may be very tired, weak, dizzy, pale, or short of breath. These problems are caused by a shortage of red blood cells called anemia.

Infections and fever: A child with leukemia may have a high fever and an infection that doesn't get better with antibiotics. This can happen because there are not enough normal white blood cells to fight the infection. Although children with leukemia may have very high white blood cell counts, the cells are not normal and may not protect against infection the way they should.

Easy bleeding or bruising: A child with leukemia may bruise easily or bleed a lot from small cuts or nosebleeds. There may be small red spots on the skin caused by bleeding from tiny blood vessels. The bleeding is caused by a lack of blood platelets, which are needed to plug holes in blood vessels.

Bone or joint pain: Some children will have bone pain or joint pain. This is from the build-up of leukemia cells near the surface of the bone or inside the joint.

Swelling of the belly (abdomen): Leukemia can cause the liver or spleen to get larger. The doctor often can feel this swelling.

Loss of appetite and weight loss: If the spleen or the liver becomes large enough, it may press against other organs like the stomach. This can limit the amount of food that can be eaten, leading to a loss of appetite and weight loss over time.

Swollen lymph nodes: Leukemia can spread to lymph nodes causing them to swell. The child, a parent, or a doctor or nurse might notice swollen nodes as lumps under the skin on the sides of the neck, in the groin, in the underarm area, or above the collarbone. Swelling of the lymph nodes inside the chest or abdomen (belly) is usually found by tests such as CT or MRI scans. (An enlarged lymph node in a child is more often a sign of an infection than leukemia, but it should be checked by a doctor and followed closely.)

Coughing or trouble breathing: The T-cell type of acute lymphocytic leukemia (ALL) often involves the thymus, a small organ found in the chest behind the breastbone. Enlargement of the thymus or of lymph nodes inside the chest can press on the nearby windpipe. This can lead to coughing or trouble breathing.

Swelling of the face and arms: A large vein that carries blood from the head and arms back to the heart passes next to the thymus. Growth of the thymus may press on this vein, causing the blood to "back up" in the veins. This can lead to swelling and a bluish-red color of the head, arms, and upper chest. It can also cause headaches, dizziness, and a change in consciousness if it affects the brain. This is known as SVC syndrome. Patients with this problem need to see a doctor right away.

Headache, seizures, or vomiting: Leukemia cells can spread outside the bone marrow into the brain and spinal cord, causing headaches, trouble thinking, weakness, seizures, vomiting, problems with balance, and blurred vision. It can spread to other organs as well.

Rashes or gum problems: In children with acute myelogenous leukemia (AML), cancer cells can spread to the gums, causing swelling, pain, and bleeding. Spread to the skin can cause spots that look like rashes.

Extreme tiredness and weakness: One rare but very serious symptom of AML is extreme tiredness, weakness, and slurring of speech. This can happen when very high numbers of leukemia cells make the blood too thick and reduce the flow of blood to the brain.

Tests used to find leukemia

Most of the symptoms of leukemia are common and can be caused by something other than cancer. The doctor will want to do certain tests to find out if the child has leukemia and, if so, what type it is.

Medical history and physical exam

The doctor will want to get a complete medical history, including how long your child has had symptoms and whether your child has any risk factors. A family history of cancer, especially leukemia, may also be important.

The physical exam will likely focus on any swollen lymph nodes, areas of bleeding or bruising, or signs of infection. A full exam of the nervous system may also be done. The child's eyes and mouth will likely be looked at carefully. The doctor will feel the belly for signs of a swollen spleen or liver.

The doctor may also get a blood sample to check your child's blood counts. If these are not normal, the doctor may refer you to a childhood cancer doctor (a pediatric oncologist), who may run one or more of the tests described below.

Types of tests used to look for leukemia in children

Blood cell counts: Blood tests will be done on blood drawn from a vein or from a "finger stick." Most children with leukemia will have too many white cells in their blood and not enough red blood cells or platelets. Also, the white blood cells will be blasts, an early type of blood cell normally found in the bone marrow but not in the blood. Changes in the numbers of different cell types and how these cells look under the microscope often make the doctor suspect leukemia. But usually a sample of bone marrow will need to be taken to be certain.

Bone marrow aspiration and biopsy: Bone marrow samples are taken by doing a bone marrow aspiration and biopsy – 2 tests that are usually done at the same time. The samples are most often taken from the back of the pelvic (hip) bones, although in some cases they may be taken from the breastbone or other bones.

These tests involve removing small amounts of bone marrow from the bone with thin needles. The samples are sent to the lab to see if cancer cells are present. These tests are also used later to see if the leukemia is responding to treatment.

For these tests, the area around the bone is numbed and the child may be given a drug to reduce pain or be asleep during the test. Once the tests are done, pressure will be applied to the site to help prevent any bleeding

Spinal tap (lumbar puncture): This test is done to look for leukemia cells in the liquid around the brain and spinal cord (cerebrospinal fluid or CSF).

For this test, the doctor first numbs an area in the lower part of the back over the spine. The doctor may also give the child medicine to make him or her sleep during the test. A small hollow needle is placed between the bones of the spine to draw out some of the fluid, which is checked for leukemia cells. It is important that someone who is an expert does this test. If the spinal tap isn't done right and some blood leaks into the CSF, leukemia cells could get into the fluid and grow there.

For children already known to have leukemia, a lumbar puncture can also be used to give chemotherapy drugs into the CSF to try to prevent or treat the spread of leukemia to the spinal cord and brain.

Lymph node biopsy: For this test, a whole lymph node is removed. If the node is near the skin's surface, this is a simple operation. But it may be more complex if the node is inside the chest or belly. Most often the child will need general anesthesia (where the child is in a deep asleep). This test is rarely needed for children with leukemia.

Lab tests for leukemia

A doctor with special training in lab tests (a pathologist) will look at all of the test samples (blood, bone marrow, CSF, and lymph node tissue) under a microscope. The doctor looks at the size and shape of the cells as well as other features to classify the cells into specific types.

A key factor is whether or not the cells look mature. Leukemia cells do not have the features of normal blood cells and do not work well in fighting infections. The most immature cells are called blasts. Having too many blasts in the sample, especially in the blood, is a typical sign of leukemia.

There are also a number of very precise lab tests the doctor might use to diagnose and classify leukemia. You might hear some of the following terms used: cytochemistry, cytogenetics, flow cytometry, FISH, and immunohistochemistry. These tests are explained in detail our document Childhood Leukemia.

Other blood tests: If the child does have leukemia, other blood tests will be done to measure certain chemicals in the blood to see how well the liver, kidneys, and other organs are working. Tests may also be done to check for infections so they can be treated right away.

Imaging tests

Imaging tests are ways of taking pictures of the inside of the body. Leukemia does not usually form tumors, so imaging tests aren't as useful as they are for other types of cancer. But some of these tests might be done in children with leukemia to get a better idea of the extent of the disease or to look for other problems like infections.

Chest x-rays: A chest x-ray can help tell if the thymus or lymph nodes in the chest are swollen. It can also help to look for pneumonia if the child seems to have a lung infection.

CT (computed tomography) scans: CT scans (sometimes called CAT scans) are special kinds of x-ray tests in which a beam moves around the body, taking pictures from different angles. This test can help tell if the leukemia has spread into lymph nodes in the chest or to organs like the spleen or liver.

Instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around your child. A computer then combines these pictures into detailed pictures of the part of the body that is being studied.

Before the scan, your child may get an injection of a contrast dye (it is put into a vein) or be asked to drink a solution of contrast liquid. This helps better outline abnormal areas in the body. Some people are allergic to the contrast and get hives or, rarely, more serious reactions like trouble breathing and low blood pressure. Be sure to tell the doctor if your child has any allergies or has ever had a reaction to any contrast material used for x-rays.

CT scans take longer than regular x-rays. Your child will need to lie still on a table while it slides in and out of the scanner. Some children may need to be sedated before the test.

Spiral CT (also known as helical CT) is now used in many medical centers. This type of CT scan uses a faster machine that uses less radiation and gives more detailed pictures.

PET/CT scan: In recent years, newer machines have been made that combine the CT scan with a PET (positron emission tomography) scan. For a PET scan, a form of sugar that contains a radioactive atom is injected into the blood. Because cancer cells in the body grow quickly, they absorb large amounts of the sugar. A special camera can then create a picture of areas of radioactivity in the body. The PET/CT scan combines the 2 pictures to give the doctor more details about any areas of cancer.

MRI (magnetic resonance imaging): An MRI is like a CT scan except that magnets and radio waves are used to make the pictures instead of x-rays. MRI scans are helpful in looking at the brain and spinal cord.

MRI scans take longer than CT scans – often up to an hour. Your child may have to lie inside a narrow tube, which can be hard for some children. Drugs are sometimes needed to help them sleep for this test. Newer, more open MRI machines may be another option, but your child will still have to lie still. The MRI machine makes loud buzzing noises and clicks that may scare your child. Some places provide headphones to block this out.

Ultrasound: Ultrasound uses sound waves to make a picture of the inside of the body. Ultrasound can be used to look for enlarged organs inside the belly. This is an easy test to have done. Your child simply lies on a table, and a technician moves a sort of wand over the part of the body being looked at.

Gallium scan and bone scan: These scans are not often done for childhood leukemias, but they may be useful if the child has bone pain that might be caused by infection or cancer in the bones. They are done in a way much like PET scans. If the child has already been found to have leukemia or if a PET scan has already been done, there is often no need for these scans.