Detection of t(11;22)(q24;q12) translocation breakpoint in paraffin-embedded tissue of the Ewing's sarcoma family by nested reverse transcription-polymerase chain reaction.

Tumors of the Ewing's sarcoma family often present a major diagnostic challenge for the pathologist. In recent years, significant progress has been made in identifying characteristic chromosomal rearrangements associated with certain solid tumors. More than 85% of Ewing's sarcoma and related tumors present a specific t(11;22) (q24;q12) balanced translocation, which generates a fusion transcript of the EWS gene and the FLI-1 gene. The cloning of the t(11;22)(q24;q12) breakpoint has raised the possibility of using a reverse transcription-polymerase chain reaction (RT-PCR) based assay as a diagnostic tool. We report an improvement of the established method, which currently depends on fresh or snap-frozen tissue, so that it is possible to use formalin-fixed, paraffin-embedded tissue as a source of RNA. The described nested RT-PCR assay enables the pathologist to investigate retrospectively archival tumor samples or to confirm the diagnosis in cases where no fresh or frozen material is available.