Variants
epithelioid Ewing sarcoma
spindle cell Ewing sarcoma
atypical pleomorphic extraosseous Ewing sarcoma
large cell Ewing sarcoma
neuro-differentiated Ewing sarcoma (pPNET, peripheral primitive neuroectodermal tumor)
Localization
skeletal Ewing sarcoma (osseous Ewing sarcoma)
extraskeletal Ewing sarcoma (extraosseous Ewing sarcoma)
- renal Ewing sarcoma
Immunochemistry
CD99+
FLI1+
Variants
post-chemotherapy neuroblastoma-like differentiation in pPNET (16944972)
Ewing sarcoma with osteoid formation (15188147)
Cytogenetics and molecular biology
Ewing family tumors are molecularly characterized by expression of chimeric transcripts generated by specific chromosomal translocations, most commonly involving fusion of the EWS gene to a member of the ETS family of transcription factors (including FLI1, ERG, ETV1, E1AF, and FEV).
Approximately 85% of reported cases of Ewing sarcoma bear an EWS-FLI1 fusion.
In rare cases, FUS can substitute for EWS, with translocation t(16;21)(p11;q24) producing a FUS-ERG fusion with no EWS rearrangement.
EWSR1 rarrangements
- t(11;22)(q24;q12) (EWSR1/FLI1 fusion gene) (85%) (11q24 and 22q12)
- t(21;22)(q22;q12) (EWSR1/ERG fusion gene) (21q22 and 22q12)
- t(2;22)(q36; q12) (EWSR1/FEV fusion gene) (2q36 and 22q12)
- t(17;22)(q21;q12) (EWSR1/ETV4 fusion gene) (17q21 and 22q12)
FUS rearrangements
- t(16;21)(p11;q22) (FUS/ERG fusion gene) (16p11 and 22q12)
- t(2;16)(q35;p11) (FUS/FEV fusion gene) (17620387)
Imbalance
| Gains | 1q+ | 8+ | 12+ |
See also
Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET)or "Ewing family of tumors" (EFTs)