A cytogenetic and molecular study for improving the quality of the pathologic diagnosis of soft tissue tumors

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The purpose of this study is to obtain cytogenetic and molecular data useful for the improvement of the diagnosis and differential diagnosis of soft tissue tumors.Results. (1) By using fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH), we demonstrated that the ring chromosome in Bednar tumor is composed of amplified material from chromosomes 17 and 22. (2) Although histopathological differentiation between dermatofibrosarcoma protuberans (DFSP) and dermatofibroma (DF) is often difficult, our CGH analysis demonstrated that the overrepresentation of 17q and 22q sequences was a common finding in DFSP but not in DF. Thus, CGH seems to be useful for distinguishing DFSP from DF. (3) A microbeam microdissection and nested RT-PCR applied on paraffin-embedded tissue of synovial sarcomas showed that SYT-SSX fusion transcript was detected in both epithelial and spindle cell components of biphasic synovial sarcomas, but not in the control tissue. Our results con … More firm that the synovial sarcoma is of monoclonal origin. (4) CGH was used to detect changes in relative chromosome copy number in 50 cases of peripheral nerve sheath tumors (PNSTs). In NF1-associated neurofibromas, most frequent losses were found in chromosomes 17 [17p11.2-p13 in 9 cases (60%); 17q24-25 in 6 cases (40%)] and 19 [19p13.2 in 8 cases (53%); 19q13.2-qter in 8 cases (53%)], whereas in sporadic neurofibromas and schwannomas, losses of chromosomes 17 and 19 were detected in less than 50% of cases. NF1-associated MPNSTs exhibited gains of chromosomes 17q and X (2/4 cases each), whereas sporadic MPNSTs showed gains of chromosome 4q (3/5 cases). (5) In 27 elastofibromas analyzed by comparative genomic hybridization, the most common recurrent gains were found at chromosomal locations Xq12-q22. The chromosomal region possibly contain genes involved in the development of at least some elastofibromas. (6) we established a new human cell line, JN-DSRCT-1, from a 7-year-old boy with desmoplastic small round cell tumor (DSRCT). The cultured cells exhibited a pathognomonic t(11;22)(p13;p12) and a chimeric transcriptional message of the Ewing's sarcoma gene exon 10 fused to the Wilms' tumor gene exon 8. This cell line will be useful for a variety of important studies such as the pathogenic mechanism, biologic behavior, and therapeutic model of human DSRCT. Less