How are Ewing tumors diagnosed?
Ewing tumors are usually found as a result of signs or symptoms that a child or teen is having. If a tumor is suspected, tests will be needed to confirm the diagnosis.
Signs and symptoms of Ewing tumors
The most common symptom of a Ewing tumor is pain at the tumor site. Most patients with bone tumors have bone pain. The pain may be caused by the tumor spreading under the outer covering of the bone (periosteum), or the pain may be from a break or a fracture of a bone that has been weakened by the tumor.
Over time, most Ewing bone tumors and almost all non-bone Ewing tumors (of soft tissue) cause a swelling or mass, which is more likely to be noticed in tumors in the arms or legs. The tumor may feel soft and warm. Tumors in the chest wall and pelvic tumors may not be noticeable until they have grown quite large.
If the tumor has spread, the child may have a fever, feel very tired, or even lose weight. Rarely, tumors near the spine can cause weakness, numbness, or paralysis in the arms or legs, while tumors that have spread to the lungs can cause shortness of breath.
Many of the signs and symptoms of Ewing tumors are more likely to be caused by something else. Still, if your child has any of these symptoms, see a doctor so that the cause can be found and treated, if needed.
Because many of these signs and symptoms are also typical of normal bumps and bruises or bone infections, Ewing tumors may not be recognized right away. The correct diagnosis is often made only after the child's condition does not go away or does not improve with antibiotics, at which time the bone is x-rayed.
Medical history and physical exam
If your child has signs or symptoms that may suggest a tumor, the doctor will want to get a complete medical history to learn about any symptoms the child is having and how long they have been present. The doctor will also do a complete physical exam, paying special attention to any areas causing pain or swelling.
If symptoms and/or the results of the physical exam suggest a child might have a Ewing tumor (or other tumor), more involved tests will probably be done. These might include imaging tests, biopsies, and/or lab tests.
Imaging tests use x-rays, magnetic fields, or radioactive substances to create pictures of the inside of the body. Imaging tests may be done for a number of reasons, including:
- To help find out if a suspicious area might be cancerous
- To determine the extent of a tumor or learn how far a cancer may have spread
- To help determine if treatment has been effective
Patients who have or may have a Ewing tumor will have one or more of these tests.
If a bone lump doesn't go away or the doctor suspects a bone tumor for some other reason, the doctor will probably order an x-ray of the area as the first test. A radiologist (doctor who specializes in reading imaging tests) can usually identify a bone tumor on an x-ray and can often recognize a Ewing tumor that involves bone. But other imaging tests may be needed as well.
Even if an x-ray strongly suggests a Ewing bone tumor, a biopsy is always needed to confirm that it is cancer rather than some other problem, such as an infection.
Magnetic resonance imaging (MRI) scan
Often, an MRI scan is done to better define an abnormal area seen on an x-ray. MRI scans can usually tell if it is likely to be a tumor, an infection, or some type of bone damage from other causes. MRI scans can also help determine the exact extent of a tumor, as they provide a detailed view of the marrow inside bones and the muscle, fat, and connective tissue around the tumor. Defining the extent of the tumor is important when planning surgery or radiation therapy.
MRI scans can also provide a good view of the brain and spinal cord, so they may be done to look for possible spread of the cancer near the spine. These tests can also be used during and after treatment to see how well the tumor is responding.
MRI scans provide detailed images of soft tissues in the body. They do this using radio waves and strong magnets instead of x-rays, so there is no radiation involved. The energy from the radio waves is absorbed by the body and then released in a pattern formed by the type of body tissue and by certain diseases. A computer translates the pattern into a very detailed image of parts of the body. A contrast material called gadolinium may be injected into a vein before the scan to better see details.
MRI scans may take up to an hour to have done. Your child may have to lie inside a narrow tube, which is confining and can be distressing. Newer, more open MRI machines can help with this, but the test still requires staying still for long periods of time. The machines also make buzzing and clicking noises that may be disturbing. Sometimes, younger children are given medicine to help keep them calm or even asleep during the test.
Computed tomography (CT or CAT) scan
CT scans of the chest are often used to see if a Ewing tumor has spread to the lungs. MRI scans are usually a bit better at defining the extent of the tumor itself, but a CT scan of the tumor may be done as well.
The CT scan is an x-ray test that produces detailed cross-sectional images of parts of the body, including soft tissues such as muscles. Instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around your child while he or she lies on a table. A computer then combines these pictures into images of slices of the part of the body being studied.
Before the scan, your child may be asked to drink a contrast solution and/or get an intravenous (IV) injection of a contrast dye that helps better outline abnormal areas in the body. If the contrast dye is to be injected, your child may need an IV line. The contrast may cause some flushing (a feeling of warmth, especially in the face). Some people are allergic and get hives. Rarely, more serious reactions like trouble breathing or low blood pressure can occur. 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, but not as long as MRI scans. Your child will need to lie still on a table while they are being done. During the test, the table slides in and out of the scanner, a ring-shaped machine that completely surrounds the table. Some people feel a bit confined by the ring they have to lie in while the pictures are being taken. In some cases, your child may need to be sedated before the test to stay still and help make sure the pictures come out well. Many medical centers now use spiral CT (also known as helical CT), which completes the scan more quickly. It also yields more detailed pictures and lowers the dose of radiation received during the test.
A bone scan can help show if a cancer has metastasized (spread) to bones in other parts of the body, and may be part of the workup for children with a Ewing tumor. This test is useful because it provides a picture of the entire skeleton at once. (A positron emission tomography [PET] scan can often provide similar information, so in some cases a bone scan may not be needed if a PET scan is done.)
For a bone scan, a small amount of low-level radioactive material is injected into a vein (intravenously, or IV). The substance settles in areas of damaged bone throughout the entire skeleton over the course of a couple of hours. Your child then lies on a table for about 30 minutes while a special camera detects the radioactivity and creates a picture of the skeleton.
Areas of active bone changes appear as "hot spots" on the skeleton because they attract the radioactivity. These areas may suggest the presence of cancer, but other bone diseases can also cause the same pattern. To make an accurate diagnosis, other imaging tests such as plain x-rays or MRI scans, or even a bone biopsy might be needed.
Positron emission tomography (PET) scan
For a PET scan, a form of radioactive sugar (known as fluorodeoxyglucose or FDG) is injected into the blood. The amount of radioactivity used is very low. Because cancer cells in the body are growing quickly, they absorb large amounts of the sugar. After about an hour, your child will lie on a table in the PET scanner for about 30 minutes while a special camera creates a picture of areas of radioactivity in the body. The picture is not finely detailed like a CT or MRI scan, but it provides helpful information about the whole body.
PET scans can be very helpful in showing the spread of Ewing tumors and in finding out whether abnormal areas seen on other imaging tests (such as a bone scan or CT scan) are tumors. PET scans can also be repeated during treatment to monitor the cancer over time.
Some newer machines can do a PET and CT scan at the same time (PET/CT scan). This lets the doctor compare areas of higher radioactivity on the PET scan with the more detailed appearance of that area on the CT.
Biopsy of the tumor
The results of imaging tests may strongly suggest a Ewing tumor, but a biopsy (removing some of the tumor for viewing under a microscope and other lab testing) is the only way to be certain. A biopsy is also the best way to tell Ewing tumors from other types of cancer.
If the tumor involves bone, it is very important that a doctor experienced in treating Ewing tumors perform the biopsy. Whenever possible, the biopsy and surgical treatment should be planned together, and the same orthopedic surgeon should do both the biopsy and the surgery. Proper planning of the biopsy location and technique can help prevent later complications and reduce the amount of surgery needed later on during treatment.
There are a couple of ways to get a sample of the tumor to diagnose Ewing tumors.
In very rare cases, if the tumor is small enough and in a good location, the surgeon can completely remove it while the child is under general anesthesia (asleep). This is called an excisional biopsy.
In most cases of suspected Ewing tumors, an incisional biopsy (taking only a piece of the tumor) is more likely to be done. The surgeon can do this either during an operation by cutting away a piece of the tumor through an opening on the skin (known as an open biopsy) or by placing a large, hollow needle through the skin and into the tumor (known as a needle biopsy or closed biopsy).
Incisional biopsies in older teens and adults are sometimes done using a local anesthetic (numbing medicine), but in children they are more often done while the child is under general anesthesia (asleep).
If a child is going to have general anesthesia for the biopsy, the surgeon may also plan other procedures while the child is asleep to avoid having to do them as separate operations later on. For example, if the tumor is thought to have spread to the chest or elsewhere, the surgeon may take a biopsy of these suspected tumors when the child is still asleep. The doctor may also do a bone marrow biopsy (see below) to see if the cancer has spread to the bone marrow spaces.
During the biopsy (while the child is still asleep), a pathologist (a doctor specializing in using lab tests to diagnose diseases) can take a quick look at the biopsy sample under the microscope. If it looks like a Ewing tumor, the surgeon may place a small flexible tube, known as a central venous catheter, into a main blood vessel in the chest area during the same operation. The catheter end lies just under or outside on the skin, which gives doctors and nurses easier access to the vein. The catheter will stay in place for several months during treatment. This is better for the child when chemotherapy is given at a later time because they will get fewer needle sticks. (See the "Chemotherapy" section.)
Bone marrow aspiration and biopsy
These tests are used to see if the cancer cells have spread into the bone marrow, the soft inner parts of certain bones. The tests aren't usually done to diagnose Ewing tumors, but they may be done once the diagnosis is made because it is important to know if the tumor has spread to the bone marrow.
Bone marrow aspiration and biopsy are usually done at the same time. In most cases the marrow samples are taken from the back of both of the pelvic (hip) bones.
These tests may be done as a separate procedure, or they may be done during the surgery to biopsy or treat the main tumor (while the child is still under anesthesia).
If the bone marrow aspiration is being done as a separate procedure, the child lies on a table (on his or her side or belly). After the area over the hip is cleaned, the skin and the surface of the bone are numbed with a local anesthetic, which may cause a brief stinging or burning sensation. In most cases, the child is also given other medicines to make them sleepy, or they might even be asleep during the procedure. A thin, hollow needle is then inserted into the bone, and a syringe is used to suck out a small amount of liquid bone marrow.
A bone marrow biopsy is usually done just after the aspiration. A small piece of bone and marrow is removed with a slightly larger needle that is twisted as it is pushed down into the bone. Once the biopsy is done, pressure is applied to the site to help stop any bleeding.
Samples from the bone marrow are sent to a pathology lab, where they are looked at and tested for cancer cells.
Testing the biopsy samples
A doctor called a pathologist looks at all biopsy specimens under a microscope to see if they contain cancer. In most cases, the specific type of cancer can be determined as well. But because cells from Ewing tumors share many of the same features as cells from other types of childhood cancer, more lab tests are often needed.
For this test, a portion of the biopsy sample is treated with special proteins (antibodies) that attach to substances that are found on Ewing tumor cells but not on other cancers. Chemicals (stains) are then added so that cells containing these substances change color and can be seen under a microscope. This lets the pathologist know that the tumor is in the Ewing family.
For this test, chromosomes (pieces of DNA) from the tumor cells are looked at under a microscope to detect any changes. As noted in the section called "Do we know what causes Ewing tumors?", cells from Ewing tumors usually have chromosome translocations, where 2 chromosomes swap pieces of their DNA. In most cases, Ewing tumor cells have translocations between chromosomes 22 and 11. Less often, the translocation involves other chromosomes. Finding these changes can help distinguish Ewing tumors from other types of cancer. Other types of chromosome changes may also be found in some Ewing tumors.
Standard cytogenetic testing usually takes about 2 to 3 weeks because the cancer cells must grow in lab dishes for a couple of weeks before their chromosomes can be seen under the microscope.
Fluorescence in situ hybridization (FISH) is a type of cytogenetic test that uses special fluorescent dyes to spot specific chromosome changes in Ewing tumors. FISH can find most chromosome changes (such as translocations) that are visible under a microscope in standard cytogenetic tests, as well as some changes too small to be seen with usual cytogenetic testing.
FISH can be used to look for specific changes in chromosomes. It can be used on blood or bone marrow samples. It is very accurate and can usually provide results within a couple of days.
Reverse transcription polymerase chain reaction (RT-PCR)
This test is another way to find translocations in tumor cells to confirm the type of tumor. RT-PCR is a very sensitive test that is often able to detect very small numbers of cells with translocations, which wouldn't be detected by cytogenetics.
RT-PCR is also useful in looking for left over or recurrent cancer after treatment. For example, if RT-PCR testing of a bone marrow sample after treatment finds cells with a typical translocation, it is likely that the cancer has not been cured and more treatment may be needed.
There are no blood tests that can be used to diagnose the Ewing family of tumors. But certain blood tests may be helpful once a diagnosis has been made.
A complete blood count (CBC) measures the levels of white blood cells, red blood cells, and platelets in the blood. An abnormal CBC result at the time of diagnosis might suggest the cancer has spread to the bone marrow, where these blood cells are made.
A blood test for levels of an enzyme called lactate dehydrogenase (LDH) is typically done at diagnosis. A high LDH level has been linked with a larger amount of tumor in the body, which indicates the cancer may be harder to treat.
Standard blood tests are done often to check a child's general health both before treatment (especially before surgery) and during treatment (such as chemotherapy) to look for possible problems or side effects. These tests may include complete blood counts to monitor bone marrow function and blood chemistry tests to measure how well the liver and kidneys are working.
Last Medical Review: 04/24/2012
Last Revised: 01/18/2013