Ewing's Sarcoma

Eric Richard Handley, MD - Case Coordinator
Joshua L Rosebrook, MD - Radiology Discussion
Priscilla S Chang, MD, PhD - Pathology Discussion
Piran Aliabadi, MD - Attending Radiologist
Steven E Seltzer, MD - Attending Radiologist

January 26, 2004

Presentation

Imaging Findings

The first two images are plain radiographs of the left humerus and shoulder. The cortex of the proximal humerus is difficult to visualize in the first image. The second shows an expansile process centered within the proximal humeral diametaphysis. There is destruction of the cortex in the lateral aspect; although the lesion looks primarily lytic, there may be a soft tissue component. It is unclear whether new bone is forming or if there is periosteal reaction present. The humeral head is not displaced. This looks like a somewhat aggressive lesion with a wide zone of transition. There is a pathologic fracture. Metastasis, perhaps from a renal cell carcinoma or thyroid tumor, should be considered in the differential diagnosis.

Additional images include bone scan, CT and MR. Whole body planar bone scan images show significant uptake in the area of the lesion. This is expected, partly due to the fracture. The lesion is not visible in the first CT image, but the other two show destruction of the cortex (it is very irregular) and the presence of soft tissue in the medullary cavity (bone windows). A T1-weighted coronal MR image shows abnormal signal in the marrow of the proximal humerus. The STIR image shows increased signal, indicating the presence of fluid and edema. The lesion enhances avidly with gadolinium.

Differential Diagnosis

It is important to remember that age is the most important factor for narrowing the differential diagnosis for bone tumors. Ewing's sarcoma is the most common bone tumor among patients of this age group (20s). Metastases are more common among patients in their 40s.

Diagnosis

Discussion

The gross specimen was resected four months after the completion of chemotherapy. The mass does include a soft tissue component. Resection histology (figure 2) reveals no residual viable tumor. There is evidence of fibrosis in the marrow as well as reactive bone formation. There are rare nests of necrotic tumor cells. Previous bone biopsy (figure 3) shows a cluster of small, round blue cells with uniform, smooth borders and scant cytoplasm. Those cells stained positive for CD99 and EWS gene rearrangement.

Radiology Discussion

Ewing's sarcoma is named for Dr James Ewing, who first described the tumor in the early 1900s. It is the fourth most common bone tumor overall, but the second most common in children; it occurs most often between the ages of 3 and 25 years with a mean of 13 years. It is twice as common in females as in males. Ewing sarcoma is a primary bone lesion but may rarely occur in the adrenals. The most common site of metastasis is the lungs; chest x-ray is appropriate for screening. Pathological diagnosis is based primarily on the translocation t(11:22)(q24;ql2) and the presence of neural markers in the tumor cells. The tumor itself is composed of small round cells and is classified as a peripheral neuroectodermal tumor (PNET).

Patients typically present with fever, anemia, leukocytosis, elevated ESR, and (eventually) a painful mass. Ewing sarcoma can occur in both long (60%) and flat (40%) bones. The long bones are more often affected in younger patients; the most common sites are the femur (25%), tibia (11%), and humerus (10%). The most commonly affected flat bones (typically older patients) are the pelvis (14%) and the ribs (6-10%). The tumor is generally centered in the metaphysis or diaphysis and does not cross the growth plate. On plain films, Ewing sarcoma appears as an aggressive bone lesion with periosteal reaction; onion skin or sunburst sings, as well as Codman triangles, may be seen. CT outlines extent of cortical involvement and may provide some information as to the amount of the soft tissue component. MRI will show a large, highly vascular soft tissue mass with extensive intramedullary spread. The typical appearance includes low T1 signal, high T2 signal, and heterogeneous contrast enhancement. Bone scan may be used to screen for metastatic disease. PET can be used to assess tumor viability after treatment. The differential diagnosis includes osteosarcoma, fibrosarcoma, neuroblastoma, and osteomyelitis.

Patients are typically treated preoperatively with radiation or chemotherapy with vincristine, dactinomycin and cyclophophamide (VAC). Adjuvant chemotherapy following surgery decreases the risk of recurrence.

References

Cotterill S. About James Ewing. CancerIndex 1999. www.cancerindex.org/bone/ewing.htm. Accessed January 26, 2004.

Ewing J. Diffuse endothelioma of bone. Proc NY Pathol Soc 1921;21: 17-24.

Coombs et al. Case of the Day: Ewing Sarcoma. Radiographics 1999; 19:241-2.

Dahnert. Radiology Review Manual, 5th Edition. Lippincott, Williams & Wilkins 2003.

• Return to the Teaching Case Database search page
• Return to Professional Education
  
• About BrighamRAD

Dear Visitors: Nothing on this World Wide Web site should be considered medical advice. Only your own doctor can help you make decisions about your medical care. It is not the policy of the Brigham and Women's Hospital Department of Radiology to provide consultation on the World Wide Web or via e-mail. If you have a specific medical question or are seeking medical care, please call the Brigham and Women's Hospital toll-free physician referral line at 1-800-294-9999.

Is this a mirrored page?
The official homepage of the BrighamRAD Teaching Case Database is http://brighamrad.harvard.edu/education/online/tcd/tcd.html