Diagnosing Sarcoma in Children

At the Stephen D. Hassenfeld Children’s Center for Cancer and Blood Disorders, part of Hassenfeld Children’s Hospital at NYU Langone, our experts diagnose and treat childhood sarcomas, cancerous tumors that occur in bone or soft tissue, which connects and supports bones and organs.

Bone tumors, including osteosarcoma and Ewing sarcoma, comprise about 9 percent of all childhood cancers and affect teens more often than young children. Rhabdomyosarcomas, a type of soft tissue cancer, account for nearly 5 percent of childhood cancers and occur mainly in children under age four.

Sarcomas are often discovered when a child or parent notices a lump on the body. In some cases, the lump hurts when touched or causes pain when the child is moving. Symptoms vary, depending on the type of sarcoma and its location in the body. They may include fatigue; pain in the arms, back, chest, legs, or pelvis; unexplained fever or weight loss; and, rarely, weakened bones that may fracture.

These symptoms resemble those of many health conditions. To diagnose a sarcoma, a doctor takes a medical history and performs a physical examination. Our pediatric oncologists may perform other tests to diagnose the type of sarcoma and determine its severity.

Blood Tests

Doctors draw blood and send it to a lab to be tested for levels of red blood cells, which carry oxygen in the blood; white blood cells, which fight infection; and platelets, which help the blood clot.

Other tests may involve checking for proteins in the blood, such as lactate dehydrogenase (LDH) or alkaline phosphatase (Alk Phos), which can be elevated in children with sarcomas.


X-ray images of the bones are the first step in determining if cancer is present. Sarcomas are often recognizable on X-ray images, so doctors may use this test if they suspect a tumor is present.

CT Scans

In a CT scan, a series of X-ray images is sent to a computer to create three-dimensional images of the body. CT scans can detect bone and soft tissue sarcomas, such as osteosarcoma, and can help your doctor determine if cancer has spread to other bones or organs, such as the lungs.

PET Scans

Your child’s doctor may order a PET scan to find out if the cancer has spread to other parts of the body. In this test, a radioactive substance that contains sugar is injected into a vein in the arm to allow for better visibility of any tumors. Because cancer cells, which grow quickly, take up larger amounts of sugar than normal cells, a PET scan can detect changes in the body before other tests can.

The radioactive substance leaves the body hours after the scan through urination or a bowel movement. Sometimes a PET scan and a CT scan are performed at the same time to provide a more complete view of the tissues and organs. PET scans are also used to help determine the cancer’s response to therapy.

MRI Scans

An MRI scan uses magnets and radio waves to created detailed three-dimensional images that are sent to a computer. These scans help your doctor define a tumor’s borders and determine its size. Sometimes a contrast dye is injected into a vein in the arm 30 minutes before the procedure. This enables tumors to become more visible on MRI.

Needle Biopsy

During a needle biopsy, the doctor removes tissue from the body for examination under a microscope. The procedure is performed while your child is sedated. Your child’s doctor uses a thin needle to withdraw fluid and cells from a bone or soft tissue tumor. If a tumor is not located near the surface of the body, the doctor may perform a needle biopsy with the guidance of ultrasound, an imaging test that uses sound waves to create images on a computer monitor.

Surgical Biopsy

Sometimes more tissue is needed for examination than can be obtained by a needle biopsy. An orthopedic oncologist performs a surgical biopsy in the hospital. Your child is given general anesthesia, and then the doctor makes a small opening in the area where the tumor is located.

He or she removes tissue and sends it to a pathologist, a doctor who studies tissues under a microscope, for analysis. The pathologist’s findings help determine the treatment plan. Different tumors require different treatment approaches.

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