Ewing's sarcoma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Michael Maddaleni, B.S.
Pathophysiology
Genetics
- 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.
- The EWSR1 gene is a member of the TET family [TLS/EWS/TAF15] of RNA-binding proteins. The FLI1 gene is a member of the ETS family of DNA-binding genes.
- Characteristically, the amino terminus of the EWSR1 gene is juxtaposed with the carboxy terminus of the ETS family gene.
- In most cases (90%), the carboxy terminus is provided by FLI1, a member of the family of transcription factor genes located on chromosome 11 band q24.
- Other family members that may combine with the EWSR1 gene are ERG, ETV1, ETV4 (also termed E1AF), and FEV.
- Rarely, TLS, another TET family member, can substitute for EWSR1.
Microscopic pathology
Ewing sarcoma is a small round blue cell tumor with regular sized primitive appearing cells:
- It consists of a homogeneous population of small round cells that have a high nuclear to cytoplasmic ratio.
- The population of small round cells are arrayed in sheets.
- There is a presence of scant cytoplasms which are pale, vacuolated, and are characterized by their faded boundaries.[1] The nuclei have intense color which make them easily visible. Mitotic activity is usually low within these cells, and cytoplasmic glycogen is also usually present.
References
- ↑ Iwamoto Y (2007). "Diagnosis and treatment of Ewing's sarcoma". Japanese Journal of Clinical Oncology. 37 (2): 79–89. doi:10.1093/jjco/hyl142. PMID 17272319. Retrieved 2012-01-04. Unknown parameter
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