Characterization of trisomy 8 in pediatric undifferentiated sarcomas using advanced molecular cytogenetic techniques.

Pediatric undifferentiated soft tissue sarcomas (USTS) are a rare group of neoplasms that are unclassifiable despite the application of immunohistochemical, cytogenetic, and molecular techniques. To date, there is a dearth of studies looking at the cytogenetic and molecular genetic alterations in such tumors. Trisomy 8, a frequent molecular alteration in neoplasia, is seen in several soft tissue sarcomas, including Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET), synovial sarcoma, and leiomyosarcoma. Because USTS share several clinicobiological features with the aforementioned tumors, the occurrence of alterations in chromosome 8 was studied in 11 pediatric USTS using a combination of interphase fluorescence in situ hybridization (FISH), spectral karyotyping (SKY), and genomic profiling with oligonucleotide array comparative genomic hybridization (aCGH). The copy number status of MYC was also assessed on the same tumors using dual-color FISH, with the aim of delineating the degree and intratumoral distribution of MYC amplification in this tumor. A near-uniform presence of an increase in MYC copy number was observed, along with an increase in chromosome 8 copy number in all the tumors. SKY and aCGH analysis of tumors exhibiting trisomy 8 confirmed the numerical imbalances. The occurrence of trisomy 8 in a subset of pediatric USTS confirms a shared genomic alteration with several other soft tissue sarcomas. Further studies are required to determine the clinical implications of such a finding.