The clinical role of molecular genetics in soft tissue tumor pathology.

Cytogenetic and molecular analysis of soft tissue tumors has yielded a wealth of information over the past decade. Some of the genetic aberrations that have been identified appear to be fairly specific for individual tumor types. It is because of this specificity that these findings harbor the promise to become useful as diagnostic and/or prognostic markers. Technical advances that allow the application of cytogenetic and molecular techniques to archival material have been crucial in this respect. Molecular genetics has already become an integral part of the work-up of some tumors, e.g., small cell sarcomas of childhood, which demonstrate fairly characteristic translocations, often involving the Ewing's sarcoma gene. Some genetic abnormalities have become established as prognostic markers, such as the deletion of the short arm of chromosome 1 for neuroblastomas. Soft tissue tumor pathology has also benefitted from major advances in identifying genes that are critical in mesenchymal differentiation or cell cycle control. MyoD is a good example of a such a gene, that has become useful as a diagnostic tool in rhabdomyosarcomas. Beyond potential practical applications of cytogenetic and molecular analyses in the diagnosis of these tumors, we also review their impact on several philosophical concepts concerning soft tissue neoplasia.