Translocation (10;11;22)(p14;q24;q12) characterized by fluorescence in situ hybridization in a case of Ewing's tumor

It is well recognized that the identification by classic cytogenetics of t( 11:22)(q24:q12) is a useful aid in the accurate diagnosis of Ewing's sarcom a and related tumors. This translocation induces the EWS/FLI-1 fusion trans cript, which can be detected by reverse transcription-polymerase chain reac tion. Recent studies have also used fluorescence in situ hybridization (FIS H) to demonstrate the translocation. The authors coupled classic cytogeneti cs and FISH on tumor cells from the original specimen, the local recurrence , and the pulmonary metastasis as well as from the xenografted tumors in a case of extraosseous Ewing's sarcoma. FISH analysis not only confirmed the cytogenetic results but also allowed the identification of a tumor-specific chromosome change, consistent with a complex translocation, t(10:ll:22), a s well as revealed other chromosomal rearrangements on both metaphases and interphase nuclei of each material. In addition this technique served to id entify, in the interphase nuclei of the original tumor, the clone that beca me dominant, from the cytogenetic point of view, in the lung metastasis and in the nude mice xenografted tumors. Current results indicate that the use of FISH on metaphases and interphase nuclei is an easy and reliable approa ch to complement or even to substitute classic cytogenetic studies for the detection of specific chromosomal rearrangements, especially for determinin g complex translocations and for describing tumoral clones with different c ytogenetic markers.