OrthoNet

Ewing’s Sarcoma

- small round cell tumor of bone occurring during adolescence
- can appear anywhere in the skeleton but usu pelvis & long tubular bones
- undistinguishable from PNET (primitive neuroectodermal tumor of bone)

Signs & Symptoms:
- pain & swelling at tumor site +/- tender soft tissue mass
- may have associated fever with elevated WBC & anemia

Xrays:
- poorly marginated, permeative lytic lesion of medullary cavity
- periosteal new bone formation with �onion-skin� pattern

Histology:
- very cellular with minimal matrix production
- small, round, closely packed cells with round uniform nuclei, indistinct cell membranes & scant cytoplasm
- arranged in dense sheets or nests separated by thin fibrous septa
- may have rosette-like structures in which center contains necrotic cells

Treatment:
- neoadjuvant chemootherapy
- wide excision (amputation vs limb salvage)
- radiation may be combined with chemotherapy to treat visceral & lymphatic metastases
- 5 yr survival = 40%