Diagnosis of Ewing Sarcoma

Executive Summary

Different tests are available for Ewing sarcoma diagnosis development, depending on signs and symptoms, age and health status, types of tumor, and earlier medical tests. Physical examination, imaging tests, and biopsies are the common diagnostic approaches for Ewing sarcoma diagnosis. The physical examination will include blood tests involving a complete blood count (CBC). The imaging tests include x-ray, Computed tomography (CT) scan, Magnetic Resonance Imaging (MRI), Positron emission tomography (PET) or PET-CT scan, and bone scan. Surgical tests will include biopsy that will consist of tissue sample extraction for cancer diagnosis and bone marrow aspiration. Other laboratory tests will include immunohistochemistry, cytogenetic tests and reverse transcription-polymerase chain reaction (RT-PCR), and molecular testing of the tumor.

Diagnosis of Ewing Sarcoma

Many tests are performed to find or diagnose cancer. They also do tests to see if cancer has spread to another part of the body from where it began. If this happens, it is called metastasis. For instance, imaging tests can represent if cancer has spread. Imaging tests show pictures of the body from the inside. Doctors can also do tests to learn which treatments would work best.

A biopsy is the sure short way for the doctor to know if an area of the body has cancer for most types of cancer. In a biopsy, the doctor takes a small tissue sample for testing in a laboratory. The doctor may suggest other tests if a biopsy cannot help diagnose.

The doctor may consider given factors when choosing a diagnostic test:

• Your signs and symptoms
• The age and general health status
• The type of cancer suspected
• The result of earlier medical tests

In addition to a physical examination, the below-mentioned tests may be used to help diagnose Ewing sarcoma ^​1​–

• Blood tests – A complete blood count (CBC)is a blood test that counts each type of blood cell. Abnormal red blood cells, white blood cells, and platelets can signify that the tumor has spread. The doctor may also check kidney and liver function and look for high levels of a particular blood enzyme called lactate dehydrogenase, which sometimes helps signal the presence of a tumor in the body. While a CBC alone cannot diagnose Ewing sarcoma, it can help doctors diagnose the disease. 

Imaging tests

• X-ray – An x-ray is a way to create a picture of the organs and tissues inside the body using a small amount of radiation. Doctors can usually find bone tumors with an x-ray.
• Computed tomography (CT or CAT) scan – A CT scan takes images of the body inside using x-rays taken from different angles. A computer combines photos into a detailed, 3-dimensional image that shows abnormalities or tumors. A CT scan is used to measure the size of the tumor and recognize enlarged lymph nodes, which may indicate the spread of cancer. A chest CT scan will be done for Ewing sarcoma to see if the tumor has spread to the lungs. Before the scan, a contrast medium dye delivers better detail to the image. This dye can be injected intravenously into the patient or given as a liquid to swallow. 
• Magnetic resonance imaging (MRI) – MRI uses magnetic fields to produce detailed body images. MRI can measure the tumor’s size and identify expanded lymph nodes, indicating that cancer has increased. A contrast medium dye is given before the scan to create a better picture. This dye can be given as a pill to swallow or injected into a patient’s vein ^​2​. 
• Positron emission tomography (PET) or PET-CT scan –  A PET scan is usually combined with a CT scan, called a PET-CT scan. Sometimes, it may be combined with MRI. A PET scan is a method to create multi-coloured images of organs and tissues inside the body. A small quantity of a radioactive substance is injected into the patient’s body which is taken up by cells using the most energy. The cancer cells which use energy actively take up the radioactive substance, and the scanner then spots this substance to produce images of the inside of the body. However, the quantity of radiation in the substance is designed to be too low to be harmful. A PET scanner then detects the substance to produce pictures of the inside of the body.
• Bone scan – Bone scan can help discover the stage of bone sarcoma. A bone scan utilizes a radioactive tracer to look inside the bone. It can help find whether cancer has spread to other places in the bone and how much damage it has caused. Healthy bone seems lighter to the camera, and areas of injury, such as those caused by cancerous cells, stand out on the image. 

Surgical tests

• Biopsy – Removal of a small amount of tissue for examination under a microscope known as a biopsy. If the tumor is in an arm or leg, an orthopaedic oncologist or an interventional radiologist with experience with Ewing sarcoma should perform the biopsy. 
• The doctor may take a sample of the tumor, bone marrow, or both during the procedure. Other tests suggest that cancer is present, but only a biopsy can make a definite diagnosis. A pathologist then analyzes the sample removed during the biopsy. 
• Bone marrow aspiration and biopsy – These two procedures are similar and often done simultaneously to examine the bone marrow and see if Ewing sarcoma is present. A bone marrow aspiration and biopsy can help determine a prognosis for a few patients’ chances of recovery. It may also provide more information about why other blood tests are abnormal. A bone marrow aspiration and biopsy is similar and often done simultaneously to evaluate the bone marrow, the fatty, spongy tissue found inside larger bones. Bone marrow has both a liquid and a solid part ^​3​. A bone marrow aspiration takes a sample of the fluid using a needle. A bone marrow biopsy removes a small quantity of solid tissue using a needle. A pathologist then reviews the samples in a lab. Pelvic bone located by the hip is a common site for bone marrow aspiration and biopsy. Doctors generally give “anaesthesia” medication beforehand to numb the area. Anaesthesia is a medication that blocks the awareness of pain. 

Other laboratory tests

Other laboratory tests may be done on the tissue sample(s) removed during a biopsy to learn more about the tumour.

• Immunohistochemistry – This test determines whether Ewing sarcoma cells are in the tissue sample ^​4​.
• Cytogenetic tests and reverse transcription-polymerase chain reaction (RT-PCR) –  These tests determine if the genetic changes that characterize Ewing sarcoma cells are present in the sample.
• Molecular testing of the tumor – Your child’s doctor may recommend running laboratory tests on a tumor or bone marrow sample to identify specific genes, proteins, and other factors unique to the tumor. Results of these tests can help determine the child’s treatment options.

References