EWING'S SARCOMA



Ewing's Sarcoma

Ewing's Sarcoma

Introduction

Ewing sarcoma is a malignant round-cell tumour. It is a rare disease in which cancer cells are found in the bone or in soft tissue. The most common areas in which it occurs are the pelvis, the femur, the humerus, and the ribs. Because a common genetic locus is responsible for a large percentage of Ewing sarcoma and primitive neuroectodermal tumours, these are sometimes grouped together in a category known as the Ewing family of tumours. The diseases are, however, considered to be different: peripheral primitive neuroectodermal tumours are generally not associated with bones, while Ewing sarcomas are most commonly related to bone. Ewing sarcoma occurs most frequently in male teenagers, with a male/female ratio of 1.6:1. Although usually classified as a bone tumour, Ewing sarcoma can have characteristics of both mesodermal and ectodermal origin, making it difficult to classify.

Causes

Genetic exchange between chromosomes can cause cells to become cancerous, like these cells from metastasized Ewing sarcoma. Ewing sarcoma is the result of a translocation between chromosomes 11 and 22, which fuses the EWS gene of chromosome 22 to the FLI1 gene of chromosome 11.

Experimental Work

Ewing sarcoma is more common in males and usually presents in childhood or early adulthood, with a peak between 10 and 20 years of age. It can occur anywhere in the body, but most commonly in the pelvis and proximal long tubular bones, especially around the growth plates. The diaphyses of the femur are the most common sites, followed by the tibia and the humerus. Thirty percent are overtly metastatic at presentation. Patients usually experience extreme bone pain. It is positive for CD99 and negative for CD45.

On conventional radiographs, the most common osseous presentation is a permeative lytic lesion with periosteal reaction. The classic description of lamellated or "onion skin" type periosteal reaction ...