Pathobiologic Markers of the Ewing Sarcoma Family of Tumors: State of the Art and Prediction of Behaviour

Figure 4

Ewing’s sarcoma with FUS translocation. This CD99-positive lesion arose from the femur and had typical Ewing’s sarcoma morphology. It was negative for an EWS rearrangement by both RT-PCR and FISH studies. In this interphase nucleus, note that one copy of the FUS locus has been divided, as evidenced by separate centromeric and telomeric gene signals, whereas the other copy has an intact, conjoined signal. Since breakapart FISH only tests a single gene locus, the partner gene in this translocation is unknown (fluorescence in situ hybridization of the FUS locus; courtesy of Dr. Ji-Yun Lee, University of Oklahoma).