It has a maximum incidence in the first and second decades of life, being rare after the third, with a 2:1 preponderance of males over females.

There is much controversy regarding the cell of origin of Ewing’s sarcoma, however more recent studies support a neuroectodermal origin.

Ewing’s tumor mainly affects the metaphyseal region of the long tubular bones and the pelvis.

Macroscopically, the bone lesion is characterized by a whitish gray color, with a soft consistency. This tumor goes beyond the cortex early, causing elevation of the periosteum with subperiosteal formation of new bone, characteristic of this disease, providing a radiographic image with an “onion skin” appearance.

Histologically, it is composed of numerous uniformly distributed, small, round cells, similar to lymphocytes, but larger in size. The argent impregnation technique in the histological study reveals a scarcity of reticulin fibers, which are only found around vessels, unlike lymphomas in which a rich network of reticulin is observed. An abundant amount of glycogen can be identified in the cytoplasm of Ewing sarcoma cells by PAS staining.

The clinical manifestations of Ewing’s sarcoma are pain, swelling, hypersensitivity of the affected part, collateral circulation, high local temperature and increased erythrocyte sedimentation rate, which can masquerade as osteomyelitis. At first it is possible that there are no radiographic changes or that the changes are small and poorly defined. As the disease progresses, the tumor induces the formation of large areas of bone lysis that corrode the spongy trabeculae and then the cortex from the inside out, giving the radiograph a “moth-eaten” appearance. Very early on, an extra-cortical tumor mass appears, in large volume, containing more tumor outside the bone than inside it.

Differential diagnosis is made with osteosarcoma, eosinophilic granuloma, rhabdomyosarcoma and osteomyelitis

Current treatment consists of preoperative multidrug therapy, lesion resection surgery followed by postoperative multidrug therapy. In surgical treatment, after resection of the lesion, reconstruction of the segment can be performed with endoprostheses, bank bone graft and autologous graft.

Assessment of the response to preoperative chemotherapy guides treatment, has prognostic value and is carried out by studying the material resected during surgery. This assessment is classified into degrees, namely:

I  – up to 50% tumor necrosis

II  – between 50% and 90% of tumor necrosis

III  – above 90% tumor necrosis

IV  – absence of histologically viable neoplasia

         Currently, with excellent responses to chemotherapy treatment and expectations of a “cure” for the disease (patients with more than fifteen years of treatment, alive and clinically well), surgical treatment with biological solutions is sought whenever possible, as they are definitive and they avoid complications arising from endoprostheses or bank grafts, whose durability is limited.

Click here to see case of Ewing Sarcoma of the pelvis.

Click here to see case of Ewing Sarcoma of the humerus