Pediatric Ewing Sarcoma

ES is not an inherited cancer that is passed down from generation to generation. It is caused by genetic changes that have occurred in the cancer cells themselves. Most commonly, ES is the result of an abnormal joining of two genes that are normally separate.

The differences between pediatric and adult ES are many, and many of the differences are not well defined. It is important to know that pediatric and adult cancers should not be compared directly (diagnosis, treatment and outcome) as they are very different diseases with the same name.

Even though pediatric ES is the second most common pediatric bone cancer and makes up 2 to 4 percent of all childhood tumors, it remains rare overall.
 
Pediatric ES comprises a group of bone and soft tissue tumors known as the Ewing family of tumors that share a number of molecular and genetic characteristics but originate from different locations and may be treated differently. This group includes:

• Ewing sarcoma of the bone. This is the most common tumor in the Ewing family.
• Extraosseous Ewing sarcoma (EOE). This rare type of tumor originates in the soft tissue surrounding the bone. It most frequently affects the chest and back, arms and legs, head and neck or tissue behind the abdomen.
• Askin tumors. These tumors affect the chest wall.
• Peripheral primitive neuroectodermal tumors (pPNET). This is a rare cancer that is similar to Ewing sarcoma of the bone and EOE.

Symptoms of pediatric ES may include:

• Pain in the area of the tumor that does not improve at night (the most common symptom) 
• Paresthesia (pins and needles, numbness) if the tumor is pushing against nerves 
• A mass or lump that can be felt and may be warm and/or tender to the touch 
• Fever of an unknown source
• A broken bone without good reason 

Less frequent symptoms include weight loss, infection and generalized bone pain.

Symptoms develop as the tumor grows. Some children will develop symptoms early, while others may not develop noticeable symptoms. Children who do not develop symptoms may be diagnosed when their doctor is performing an exam or test for another condition.

Many of the symptoms of pediatric ES are similar to common complaints in an active child or adolescent, making the diagnosis of ES difficult based on symptoms alone. Most children will experience symptoms on average for three to nine months prior to being definitively diagnosed.

Both boys and girls can be diagnosed with ES, but boys are diagnosed slightly more often than girls. Caucasian children develop ES more frequently than Asian-American or African-American children. Although ES can be diagnosed at any age, the majority of cases are diagnosed between 10 and 20 years of age for both boys and girls. ES is uncommon in children who are less than 5 years old, but it has been known to occur in this age group.

Diagnosis of Pediatric Ewing Sarcoma

If your child has symptoms of ES, the doctors at Riley at IU Health can perform the following exams and tests to make a diagnosis:

• Physical examination. Diagnosing pediatric ES typically begins with a physical examination by your child’s doctor. Any abnormal findings may be further evaluated if there is concern for a tumor. 
• X-ray. X-ray images of a concerning area are often the next step in diagnosing a tumor. In some cases, X-rays will demonstrate findings consistent with a growth in or near the bone, or they will demonstrate abnormal breaks in a child’s bones that warrant further evaluation.
• Magnetic resonance imaging (MRI). MRI is an imaging procedure that uses a magnetic field instead of radiation to show tumors in bone, muscle and soft tissue. MRI allows doctors to evaluate the area of concern in greater detail.
• Computed tomography (CT). CT creates multiple detailed or three-dimensional images of bone, tissue and blood vessels. Doctors may also use this fast, painless imaging procedure to evaluate the area of concern.
• Blood tests. A blood test may be ordered to look at the red blood cells, white blood cells, platelets and blood chemistries that can be affected in children with cancers. 
• Biopsy. Ultimately, a sample of the tumor itself (biopsy) is needed to confirm the diagnosis of pediatric ES. Depending on the location and size of the tumor, a biopsy can either be done with a needle, by surgical removal of a small piece of the tumor or, in some cases, by surgical removal of the entire tumor. The pieces of tumor are then specially prepared and placed on microscope slides for evaluation by the pathologist who provides a final tissue diagnosis. 

Once a tumor has been diagnosed as ES, the oncology team will obtain additional tests to determine if the tumor has spread to other areas of the body. This is called staging and may include a chest X-ray, bone scans, additional MRI or CT imaging, a bone marrow biopsy or a bone marrow aspiration.