Synovial sarcoma specific translocation on associated with both epithelialand spindle cell components

The biphasic subtype of synovial sarcoma consists of both epithelial and sp indle cell components. To address the relationship between the different ce llular components found in synovial sarcoma, we deduced the presence of the synovial sarcoma-specific der(X)t(X;18)(p11.2;q11.2), and involvement of t he SSX1 gene in both the epithelial/glandular and spindle cell components o f 3 biphasic synovial sarcomas with wide ranging proportions of each of the 2 elements. This has been achieved using a 2-color fluorescence in situ hy bridization (FISH) methodology that we had developed recently for analysis paraffin-embedded material. The presence of the rearrangement could be dedu ced in histologically defined regions and the results showed clearly that t he rearrangement was present in both cellular components. This finding prov ides direct genetic evidence for biphasic synovial sarcomas being clonal an d truly biphasic. (C) 1999 Wiley-Liss, Inc.