EWS/FLI-1 fusion transcript detection and MIC2 immunohistochemical staining in the diagnosis of Ewing's sarcoma.
Ewing's sarcoma (ES) and other primitive peripheral neuroectodermal tumors (pPNETs) can present a significant diagnostic problem, as they may morphologically resemble other small round cell tumors (SRCTs) of childhood. However, ES/pPNET is known to carry a characteristic t(11;22)(q24;q12), the detection of which may aid diagnosis. The recent identification of the EWS and FLI-1 genes flanking the translocation break point has enabled reverse transcriptase-polymerase chain reaction (RT-PCR) to be used to detect the putative chimeric transcription factor mRNA produced by the fusion gene. We have assessed the RT-PCR method of detection by examining 40 cases of ES for the presence of EWS/FLI-1 transcripts. Twenty-six (76%) of the 34 cases with intact mRNA yielded fusion transcripts. Four different transcript sizes were detected and two tumors contained two transcripts of different size. No transcripts were detected in a control group of non-ES/pPNET SRCTs. Eight cases with intact mRNA were transcript negative. The MIC2 cell surface antigen, which is reported to be present in over 95% of ES/pPNETs, was present in 32 of 33 tumors (97%), including all 24 EWS/FLI-1 transcript-positive cases examined. Hence MIC2 is a useful screen for ES, with RT-PCR detection of t(11;22) being the optimal method for confirming the diagnosis.
Lee
C S
CS
Department of Pathology, University of Melbourne, Parkville, Victoria, Australia.
Southey
M C
MC
Waters
K
K
Kannourakis
G
G
Georgiou
T
T
Armes
J E
JE
Chow
C W
CW
Venter
D J
DJ
D000071443:12E7 Antigen; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000032:analysis*; D015815:Cell Adhesion Molecules / Q000032:analysis*; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000235:genetics*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D016133:Polymerase Chain Reaction; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins / Q000032:analysis*; D012512:Sarcoma, Ewing / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics*; D015534:Trans-Activators / Q000032:analysis* / Q000235:genetics*; D014157:Transcription Factors / Q000032:analysis* / Q000235:genetics*; D014158:Transcription, Genetic
D000071443:12E7 Antigen; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules; D004268:DNA-Binding Proteins; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; C103572:SH2D1B protein, human; D015534:Trans-Activators; D014157:Transcription Factors