| Epidemiology | peripheral neuroepithelioma is a very rare tumour (1% of all sarcomas); Ewing's sarcoma represents 5 to 15% of malignant bone and soft tissue tumours; two thirds of cases of Ewing's tumours occur before age 35 years, with a median age of 20 years. |
| Clinics | peripheral neuroepithelioma typically occurs in the extremities (buttock and upper thigh, shoulder and upper arm); esthesioneuroblastoma probably develops from the olfactive placode, in the nasal vault Ewing's sarcoma of bones affects preferentially long bones (especially the femur), the pelvis, and the ribs; extraskeletal Ewing's sarcoma occur in the paravertebral region and chest wall, often in association with vertebrae and ribs, and in lower extremities Askin's tumour is a paediatric tumour affecting mostly the chest wall and ribs |
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| Ewing's tumor : the tumor is composed of blastematous tissue with some differentiated glomerular structures associated with mesenchymal tissue and tubules. Courtesy Pierre Bedossa. |
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| Pathology | peripheral neuroepithelioma show sheets or lobules of small round-cells with a scarce cytoplasm; cells are often arranged in rosettes with a neurofibrillar center (Homer-Wright rosettes) esthesioneuroblastoma is histologically very similar to neuroblastoma; rosettes may be present Askin's tumour seems to be more related to neuroepithelioma than to Ewing's sarcoma Ewing's sarcoma forms sheets of uniform small round-cells, sometimes arranged in a lobular pattern; the cytoplasm is scanty, pale stained and often vacuolated (glycogen); Ewing's sarcoma is considered as the less differentiated form of the Ewing's tumours family |
| Treatment | the treatment of Ewing's tumours is generally based on combined therapy with adjuvant chemotherapy, surgical resection and radiotherapy. |
| Prognosis | combined therapies have largely improved the prognosis of Ewing's tumours in the recent years; the prognosis is mainly determined by the presence of metastases at the time of diagnosis (15 to 35% of the cases); the 5-year survival rate is 10-35% in patients with mestastases, and 54-74% for patients with a localised disease at presentation. |
Cytogenetics
Morphological | about 90% of Ewing's tumours, whatever their type, show a t(11;22)(q24;q12); the translocation results in the fusion of the EWS gene with the transcription factor gene FLI1, leading to a hybrid transcript and an oncogenic chimeric protein; in about 5% of the cases, the EWS gene is involved in variant translocations: t(21;22)(q12;q12) and t(7;22)(p22;q12), leading to fusions EWS-ERG and EWS-ETV1, respectively. |
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| t(11;22)(q24;q12) in Ewing sarcoma, G- banding - top: courtesy Jean Luc Lai (with trisomy 8 on the right); - bottom: courtesy G. Reza Hafez, Eric B.Johnson, and Sara Morrison-Delap, UW Cytogenetic Services |
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| Cytogenetics Molecular | additional anomalies in Ewing's tumours mainly consist in chromosome gains: +8 (45% of the cases) and, with a much lower frequency, trisomies 2, 5, 7, 9, 12 (between 10 and 15% of the cases); trisomy 1q, through unbalanced t(1q;16q), is observed in about 25% of the cases |
| The Ewing family of tumors--a subgroup of small-round-cell tumors defined by specific chimeric transcripts. |
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| A variant Ewing's sarcoma translocation (7;22) fuses the EWS gene to the ETS gene ETV1. |
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| PMID 1330877 |
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| Chromosomes in Ewing's sarcoma. I. An evaluation of 85 cases of remarkable consistency of t(11;22)(q24;q12). |
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