الفهرس 
LaporatoryOnly 14 pages are availabe for public view
 |  | from | 94 |  |  |
| | | from | 94 | | |
Abstract
Ewing’s sarcoma is the second most frequent primary malignant bone cancer, after osteosarcoma. It is slightly more common in boys (55:45 male:female ratio). The most common age of diagnosis is the second decade of life,
pain is the most common presenting symptom in patients with Ewing’s sarcoma. is often mistaken for ”bone growth” or injuries resulting from sport or everyday activities. may be accompanied by paresthesia in some cases. Pain as the initial symptom may be followed by a palpable mass.
Most Ewing’s sarcomas occur in bones. flat bones of the axial skeleton are relatively more commonly affected, and in long bones, Ewing’s sarcoma, unlike osteosarcoma, tend to arise from the diaphyseal rather than the metaphyseal portion. The most common sites of primary Ewing’s sarcoma are the pelvic bones, the long bones of the lower extremities, and the bones of the chest wall.
The initial imaging investigation when an osseous lesion is suspected is usually a radiograph in two planes. Tumor-related osteolysis, detachment of the periosteum from the bone (Codman triangle), and spiculae of calcification in soft tissue tumor masses suggest the diagnosis of a malignant bone tumor, The most precise definition of the local extent of disease, including the intramedullary portion and the relation of the lesion to adjacent blood vessels and nerves, is provided by magnetic resonance imaging.
As for other malignant diseases, the definitive diagnostic test is the biopsy. Although the diagnosis can be made by fine needle aspiration biopsy or by core needle biopsy, the most adequate sampling is achieved by open biopsy, Classic Ewing’s sarcoma, is composed of a monotonous population of small round cells with high nuclear to cytoplasmic ratios arrayed in sheets.The cells have scant, faintly eosinophilic to amphophilic cytoplasm, indistinct cytoplasmic borders, and round nuclei with evenly distributed, finely granular chromatin and inconspicuous nucleoli.
Strong expression of the cell-surface glycoprotein p30/32MIC2 (CD99) is characteristic of Ewing’s sarcoma and strong, diffuse membrane staining in a ”chain-mail pattern” is present in 95%–100% of Ewing’s sarcoma with one or more of the monoclonal antibodies to this antigen, including O13, 12E7, and HBA71, In addition, Ewing’s sarcoma is immunoreactive for vimentin . More differentiated Ewing’s sarcomas (peripheral primitive neuroectodermal tumors [pPNETs]) may also show immunohistochemical evidence of neural differentiation, staining for neuron-specific enolase (NSE), S-100 protein, Leu-7, and/or PgP 9.5. Ewing’s sarcoma is immunoreactive for cytokeratins in up to 20% of cases, with diffuse immunoreactivity for cytokeratins noted in up to 10% of cases.
The management of Ewing’s sarcoma includes chemotherapy and local control .Current treatment schedules favor primary induction chemotherapy, followed by local therapy and adjuvant chemotherapy. For several decades, radiotherapy was regarded as the standard local treatment modality,contemporary orthopedic surgery, however, is aimed at preserving function and improving limb salvage rates without compromising survival rates.In planning the optimal local therapy, an interdisciplinary approach involving experts experienced in this field is essential. If pre-operative imaging suggests that it will likely be possible to resect the lesion with wide margins, wide resection without irradiation is the treatment of choice for primary lesions. If the possibility of achievement of adequate surgical margins is uncertain, pre-operative radiotherapy should be added. As Ewing’s sarcomas are sensitive to both chemotherapy and irradiation, even questionable candidates for limb salvage may be eligible after neoadjuvant chemotherapy with or without irradiation. If the surgical margins are found to be inadequate after surgery, postoperative radiotherapy may also be added. When surgical margins are certain to be inadequate at preoperative imaging, amputation may be the only surgical option available.
The main reconstructive options include autogenous bone grafts, structural bone allografts (intercalary or osteoarticular), and metallic endoprosthetics. Allografts and endoprosthetics may also be used as part of a composite reconstruction. Autogenous bone grafts may be vascularized (e.g., fibula). Local treatment should be individually adapted depending upon the site and size of the tumor, the anatomical structures near the tumor, the patient’s age, and individual preference.Infection, nonunion, and fracture may complicate the surgery, especially since patients will be receiving continuing chemotherapy and possibly radiotherapy.