CHROMOSOMAL TRANSLOCATIONS IN HUMAN SOFT-TISSUE SARCOMAS BY INTERPHASE FLUORESCENCE IN-SITU HYBRIDIZATION

In soft tissue sarcomas, clonal rearrangement of chromosomes has been shown by cytogenetic analysis to be unique and specific for tumor type s. The development of fluorescence in situ hybridization (FISH) has al lowed detection of chromosomal rearrangements in the interphase nuclei isolated from paraffin-embedded tissues. Three kinds of translocation s in the interphase nuclei that were isolated from 47 cases of soft ti ssue sarcomas were examined by FISH with chromosome-specific DNA probe s of centromeric and total probes. Of 47 soft tissue sarcomas 42 (89.4 %) revealed tumor-specific translocations by retrospective cytogenetic analysis. Translocation t(X;18) was detected in 25/28 synovial sarcom as; translocation t(11;22) in 5/6 Ewing's sarcomas and primitive neuro ectodermal tumors (PNET); and translocation t(12;16) was found in 12/1 3 liposarcomas, including 10 myxoid and two round cell types as clonal chromosomal aberrations specific for both subtypes. Based on the cyto genetic analysis, Ewing's sarcoma is related closely with PNET as show n by MIC2-protein reactivity. Other cytogenetic findings of translocat ion t(12;16) indicate that round cell liposarcomas share chromosomal c hanges with myxoid liposarcomas, and further suggest that both tumor s ubtypes of liposarcoma may possess common precursor cells. FISH is a u seful aid in determining the tumor type of soft tissue sarcomas with r egard to histogenetic origin.