Cytogenetics and Molecular Genetics of Myxoid Soft-Tissue Sarcomas

Myxoid soft-tissue sarcomas represent a heterogeneous group of mesenchymal tumors characterized by a predominantly myxoid matrix, including myxoid liposarcoma (MLS), low-grade fibromyxoid sarcoma (LGFMS), extraskeletal myxoid chondrosarcoma (EMC), myxofibrosarcoma, myxoinflammatory fibroblastic sarcoma (MIFS), and myxoid dermatofibrosarcoma protuberans (DFSP). Cytogenetic and molecular genetic analyses have shown that many of these sarcomas are characterized by recurrent chromosomal translocations resulting in highly specific fusion genes (e.g.,FUS-DDIT3in MLS,FUS-CREB3L2in LGFMS,EWSR1-NR4A3in EMC, andCOL1A1-PDGFBin myxoid DFSP). Moreover, recent molecular analysis has demonstrated a translocationt(1; 10)(p22; q24) resulting in transcriptional upregulation ofFGF8andNPM3in MIFS. Most recently, the presence ofTGFBR3andMGEA5rearrangements has been identified in a subset of MIFS. These genetic alterations can be utilized as an adjunct in diagnostically challenging cases. In contrast, most myxofibrosarcomas have complex karyotypes lacking specific genetic alterations. This paper focuses on the cytogenetic and molecular genetic findings of myxoid soft-tissue sarcomas as well as their clinicopathological characteristics.