DETECTION OF T(11-22)(Q24-Q12) TRANSLOCATION BREAKPOINT IN PARAFFIN-EMBEDDED TISSUE OF THE EWINGS-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 h as 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 tra nslocation, which generates a fusion transcript of the EWS gene and th e FLI-1 gene. The cloning of the t(11;22)(q24;q12) breakpoint has rais ed the possibility of using a reverse transcription-polymerase chain r eaction (RT-PCR) based assay as a diagnostic tool. We report an improv ement of the established method, which currently depends on fresh or s nap-frozen tissue, so that it is possible to use formalin-fixed, paraf fin-embedded tissue as a source of RNA. The described nested RT-PCR as say enables the pathologist to investigate retrospectively archival tu mor samples or to confirm the diagnosis in cases where no fresh or fro zen material is available.