[Ewing's tumor: current knowledge and ignorance]

The diagnosis of Ewing's malignant tumor in the young still raises major problems, either from a clinical point of view because of its rarity, its pluri-potentiality and various symptoms, or on imaging because of its numerous pitfalls. Accordingly the disease is often misdiagnosed as osteomyelitis. Only a high quality biopsy can determine histological diagnosis of undifferentiated small round cell tumor. The chromosomic study shows a specific (11;22)(q24;q12) translocation, and immunocytochemistry and molecular biology show the tumor's neuroectodermal origin. For 20 years, therapy tended toward first line tumor chemoreduction, followed, when appropriate, by complete resection and orthopedic reconstruction of the bone. Radiotherapy, which is responsible for long-term sequelae is now increasingly restricted to inaccessible or incompletely excised tumors. More intensive chemotherapy is being examined in patients with poor prognosis factors such as a negative response to induction chemotherapy, a significant mass or metastases. As a result of new strategies, disease-free survival rate is now between 60-70%. The management of this disease is highly multidisciplinary and patients will now be included in multicentric controlled therapeutic trials. Long term follow-up has to be carried out following completion of treatment.