Ewing sarcoma (chest wall)
Ewing sarcoma family of tumours (ESFT), also referred as Ewing sarcomas of the chest wall, are malignant tumours affecting children and young adults, originating either from the osseous structures or the soft tissues of the chest wall.
On imaging, they are usually characterised as a large extrapulmonary invasive soft tissue masses that are heterogeneous due the presence of haemorrhage, necrosis, or cystic changes. Enhancement is intense and there is increased uptake in the nuclear medicine studies. Calcifications are uncommon and a small pleural effusion is frequently present.
Originally a small round blue cell tumour of the soft tissues of the chest was described and became known as an Askin tumour or peripheral primitive neuroectodermal tumour (pPNET). All three entities are now thought to belong to the same tumour family, now referred to as Ewing sarcoma family of tumours (ESFT) 1-3.
Not surprisingly the demographics of these chest wall tumours are similar to those of Ewing sarcomas elsewhere, seen predominantly in children and young adults 4. Ewing sarcomas account for 10-15% of all primary chest wall tumours 6.
These tumours may either arise in the osseous structures of the chest wall (ribs, scapula, sternum of clavicle) or less frequently in the soft tissues of the chest (it was these latter lesions that were described as Askin tumours/pPNET) 3. They can either be single or multiple masses and present as rapidly growing masses.
Typically they present as rapidly growing, often painful warm soft tissue masses 6.
Ewing sarcoma family of tumours share common cytogenetic and microscopic features. They demonstrate non-random t(11;22)(q24;q12) chromosome rearrangement resulting in the formation of the EWS-ETS fusion gene, with variable degrees of differentiation (e.g. Homer Wright rosettes) 1-3. As the tumour progresses, cystic degeneration can occur.
Despite their aggressive nature, these tumours tend to (at least initially) displace adjacent structure (e.g. lung, diaphragm). Direct invasion is however seen especially in larger tumours 3. May cause rib destruction.
On CT, these tumours are typically ill-defined with heterogeneous attenuation and multiple areas of cystic degeneration. Solid components demonstrate enhancement following the administration of contrast. Pleural effusions are common but are usually small 4. Calcification is uncommon 4.
When these tumours arise in bone onion skin periosteal reaction may be evident.
Typically these masses are heterogeneous on MRI as well as CT on account of numerous areas of necrosis, degenerative cystic change and haemorrhage 3-4. Smaller tumours are more likely be homogeneous 4.
- T1: iso- or hyperintense to muscle 3
- T2: heterogeneous high signal
- T1 C+ (Gd): prominent heterogeneous enhancement
When tumours arise in the paravertebral region, direct extension through the neural exit foramen may be seen 3.
Treatment and prognosis
Treatment involves surgical resection and neoadjuvant chemotherapy +/- radiotherapy. The strongest predictor of outcome is the presence or development of distant metastases 5-6. In patients whose tumour is confined to the chest, long-term survival is achievable. Overall 5-year survival is between 15-48% 6.
The differential is that of other tumours of the chest wall, especially other sarcomas, including:
- usually indistinguishable
- thorax is a rare location
- tumour matrix ossification/calcification
- thorax is an atypical location
- chest wall and pleural metastases
- usually the most common primary tumours are themselves located in the chest: lung cancer and breast cancer
- homogeneous, vividly enhancing mass without rib destruction
solitary fibrous tumour of the pleura
- chest wall involvement rare
- 1. Burchill SA. Ewing's sarcoma: diagnostic, prognostic, and therapeutic implications of molecular abnormalities. J. Clin. Pathol. 2003;56 (2): 96-102. J. Clin. Pathol. (link) - Free text at pubmed - Pubmed citation
- 2. Iwamoto Y. Diagnosis and treatment of Ewing's sarcoma. Jpn. J. Clin. Oncol. 2007;37 (2): 79-89. doi:10.1093/jjco/hyl142 - Pubmed citation
- 3. Tateishi U, Gladish GW, Kusumoto M et-al. Chest wall tumors: radiologic findings and pathologic correlation: part 2. Malignant tumors. Radiographics. 23 (6): 1491-508. doi:10.1148/rg.236015527 - Pubmed citation
- 4. Winer-muram HT, Kauffman WM, Gronemeyer SA et-al. Primitive neuroectodermal tumors of the chest wall (Askin tumors): CT and MR findings. AJR Am J Roentgenol. 1993;161 (2): 265-8. AJR Am J Roentgenol (abstract) - Pubmed citation
- 5. Saenz NC, Hass DJ, Meyers P et-al. Pediatric chest wall Ewing's sarcoma. J. Pediatr. Surg. 2000;35 (4): 550-5. doi:10.1053/jpsu.2000.0350550 - Pubmed citation
- 6. Doherty G. Current diagnosis and treatment surgery Thirteenth Edition (LANGE CURRENT Series). McGraw-Hill Medical. ISBN:0071635157. Read it at Google Books - Find it at Amazon