Diagnosis

Clinical findings

Staging

Causes

Incidence

TEF can occur at any age, but they are most common in teens and are less common among young adults and young children (the peak between 10 and 20 years of age). They are rare in older adults. Ewing sarcoma occurs most frequently in male teenagers, with a male/female ratio of 1.6:1.

Ewing tumors occur most often in whites (either non-Hispanic or Hispanic). They are less common among Asians. The reason for this is not known.

Most Ewing tumors occur in the bones. The most common sites are the pelvis (hip bones), the chest wall (such as the ribs or shoulder blades), and the legs, mainly in the middle of the long bones. (In contrast, osteosarcoma usually occurs at the ends of the long bones, especially around the knees.) Extraosseous Ewing tumors can occur almost anywhere.

The exact cause of Ewing sarcoma is not fully understood. There seems to be no known risk factors or prevention measures avaliable. However, researchers have discovered chromosomal changes in a cell's DNA that can lead to Ewing sarcoma formation. These changes are not inherited. They develop in children after they are born for no apparent reason.

In nearly 85 %t of these cases, the change involved the fusing of genetic material between chromosomes #11 and #22. When a certain piece of chromosome #11 is placed next to the EWS gene on chromosome #22, the EWS gene gets "switched on." This activation leads to an overgrowth of the cells and eventually the development of cancer. The exact mechanism remains unclear, but this important discovery has led to improvements in diagnosing Ewing sarcoma

A tumor is described by size, where it originated, and whether it has spread. This is called staging. A TEF is staged as either localized (involving only the site of origin and nearby tissues) or metastatic (involving spread to distant parts of the body).

The formal (and more detailed) staging system for Ewing tumors is the American Joint Committee on Cancer (AJCC) system for bone cancer.

The following are the most common symptoms of Ewing's sarcoma. However, each child may experience symptoms differently. Symptoms may include, but are not limited, to the following:

§ pain around the site of the tumor

§ swelling (mass) and/or redness around the site of the tumor

§ fever

§ weight loss, decreased appetite

§ fatigue

§ paralysis and/or incontinence (if the tumor is in the spinal region )

§ symptoms related to nerve compression from tumor (i.e., numbness, tingling, paralysis, etc.)

At this time unfortunately, there are no special tests that can help with early detection of Ewing’s and PNET.

The most often described of the EFT is usually a lump on the trunk with or without pain. Sometimes there may be increased heat over the lump, and in some instances the child may have general symptoms, such as fatigue or stomach aches, and not feel well. Unfortunately, children have many, many lumps which can be painful due to normal play activities, so unless the lump persists for a prolonged period of time, there should be no cause for concern. If the lump is warm to the touch, and/or the child has fever, the child should be seen by a health professional.

The diagnosis of a TEF begins with recognition of certain signs and symptoms suggesting the disease might be present. The most common symptom of a TEF of the bone is pain. Pain occurs in about 85% of patients. The pain may be caused by the spread of the tumor under the periosteum (tissue covering the bone). Or the pain may be from a fracture (broken bone) in a bone that has been weakened by the tumor. Because these signs and symptoms are also typical of normal bumps and bruises or bone infections, some cases are not easily recognized. Only after the child’s condition does not resolve quickly or is not improved by antibiotics is the diagnosis questioned.

In addition to a complete medical history and physical examination of your child, diagnostic procedures for Ewing's sarcoma may include:

¤ Imaging tests (such as x-rays, MRI, CT, and PET scans) create pictures of the inside of the body.

On conventional radiographs, the most common osseous presentation is a permeative lytic lesion with periosteal reaction. The classic description of lamellated or "onion skin" (or "onion peel") type periosteal reaction is often associated with this lesion (Image 9.15). Plain films add valuable information in the initial evaluation or screening. The wide zone of transition (e.g. permeative) is the most useful plain film characteristic in differentiation of benign versus aggressive or malignant lytic lesions.

MRI should be routinely used in the work-up of malignant tumors. MRI will show the full bony and soft tissue extent and relate the tumor to other nearby anatomic structures (e.g. vessels). Gadolinium contrast is not necessary as it does

Image 9.15 Onion peel. A - anteroposterior and B - lateral views. Classically described in Ewing’s tumor but it is not pathognomonic (sometimes also seen in osteomyelitis or osteogenic sarcoma).

not give additional information over noncontrast studies, though some current researchers argue that dynamic, contrast enhanced MRI may help determine the amount of necrosis within the tumor, thus help in determining response to treatment prior to surgery.

CT can also be used to define the extraosseous extent of the tumor, especially in the skull, spine, ribs and pelvis. Both CT and MRI can be used to follow response to radiation and/or chemotherapy.

¤ 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.

There are a couple of ways to get a sample of the tumor to diagnose Ewing tumors:

Excisional biopsy - 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.

Incisional 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).