Soft tissue tumors

Soft tissue tumors are highly heterogeneous with more than 100 subtypes. The chapter describes a large number of fibroblastic/myofibroblastic tumor entities. Alveolar rhabdomyosarcomas (ARMS) and embryonal rhabdomyosarcomas (ERMS) show largely similar patterns of genomic imbalances, although most of them occur at higher frequencies among the latter. The chromosome numbers of 70 undifferentiated pleomorphic sarcomas varied from near haploidy to hyperoctaploidy. Cytogenetic analyses have revealed that practically all soft tissue tumor types harbor acquired chromosome aberrations. The type of aberrations and the level of karyotypic complexity vary considerably from one tumor entity to another. At one end are the pathognomonic translocations that by themselves are extremely useful diagnostic signatures. Detection of such aberrations, by cytogenetic or molecular genetic means, is useful in the diagnostic setting when combined with clinicopathologic data. The prognostic impact of the genetic aberrations identified in soft tissue tumors is largely unknown.