Table 2. Translocations and other genetic alterations in the most common mediastinal sarcomas.
| Tumor type | Genetic alteration | Recurrent fusion or abnormality |
|---|---|---|
| Synovial sarcoma | t(X;18)(p11;q11), t(X;20)(p11;q13) | SS18-SSX1, SS18-SSX2, SS18-SSX4, SS18L1-SSX1 |
| Well-differentiated and dedifferentiated liposarcoma | Supernumerary ring and giant chromosome markers with amplification of 12q13-15, including MDM2 and CDK4 | Cell cycle dysregulation, overexpression of MDM2 and CDK4 |
| Leiomyosarcoma | Generally complex karyotypes with numerous gains and losses. No consistent recurrent aberrations at the chromosomal level | None |
| Ewing sarcoma/PNET | t(11;22)(q24;q12), t(21;22)(q22;q12), t(7;22)(q22;q12), t(17;22)(q21;q12), t(2;22)(q36;q12) | EWSR1-FLI1, EWSR1-ERG, EWSR1-ETV1, EWSR1-ETV4, EWSR1-FEV |
| Solitary fibrous tumor* | Intrachromosomal inversion of 12q13 region | NAB2-STAT6 |
| SMARCA4-deficient thoracic sarcoma | Point mutations leading to loss of SMARCA4 | Dysregulation of SWI/SNF (BAF) complex |
| Malignant peripheral nerve sheath tumor | Various somatic alterations in CDKN2A, NF1, EED, SUZ12, SMARCB1 (epithelioid variant) | Dysregulation of polycomb repressive complex 2 (PRC2) |
*, solitary fibrous tumor is generally not regarded as a “true sarcoma”, however, it is included here due to its potential for malignant and/or aggressive behavior and relatively common occurrence within the mediastinum. PNET, peripheral neuroectodermal tumor.