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Type:
Educational Exhibit
Keywords:
Musculoskeletal soft tissue, Paediatric, Oncology, CT, MR, Ultrasound, Education, Cancer
Authors:
A. Alexander, L. Naffaa, G. Gaisie, S. Ganapathy, M. Rubin; Akron/US
DOI:
10.1594/ecr2015/C-1392
Conclusion
Extraosseous Ewing sarcoma should be considered when a circumscribed,
solid,
aggressive appearing mass is encountered in an older child/adolescent in the extremities or in close proximity to the skeletal structures.
Familiarity of the radiologist with its radiological appearance is essential in providing an accurate differential diagnosis.
Features including flow voids,
T1 signal similar to muscle,
proximity to bone,
cystic changes/necrosis and lack of calcification all help consider extraosseous Ewing sarcoma and narrow the differential diagnosis.
While a predominantly cystic/necrotic mass with imaging features similar to what we have demonstrated favor extraosseous Ewing sarcoma,
this entity should also be considered when a lesion presents as a predominantly solid mass,
similar to rhabdomyosarcoma,
or in close proximity to skeletal structures,
similar to synovial sarcoma.
Knowledge of pathological correlates provides the radiologist with a foundation to better understand the variability of radiological findings,
including the presence of rich vascularity in cystic or necrotic regions,
and hemorrhage.
Solidly packed blue round cells and CD99 positivity,
along with FLI1 staining to recognize chromosome 11;22 translocation,
help confirm the diagnosis.