Ewing sarcoma

Digital cases (Digital slides)

 HPC:31 : Ewing sarcoma
 HPC:132 : Ewing sarcoma
 HPC:182 : Ewing sarcoma
 HPC:376 : EWSR1-FLI1+ bone-forming Ewing sarcoma (EWSR1-FLI1+ small cell osteosarcoma)

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)
 bone-forming Ewing sarcoma (small cell osteosarcoma)

Localization

 skeletal Ewing sarcoma (osseous Ewing sarcoma)
 extraskeletal Ewing sarcoma (extraosseous Ewing sarcoma)

• renal Ewing sarcoma

Immunochemistry

 CD99+ (MIC2+)
 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#)

Chromosomal imbalance (CGH)

See also

 Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET)or "Ewing family of tumors" (EFTs)