title: Molecular confirmation of Ewing sarcoma.
abstract: OBJECTIVE
  To analyze retrospectively results of reverse transcription polymerase chain reaction (RT-PCR) testing and demographic information in patients with known or suspected Ewing sarcoma/primitive neuroectodermal tumor family of tumors referred to the National Cancer Institute and to describe factors influencing the determination of molecular marker status.
  
  
  METHODS
  Tumor samples from 76 patients from February 1997 to December 1999 were analyzed. In all cases, the diagnosis of this family of tumors was confirmed by histopathologic review.
  
  
  RESULTS
  In 58 patients, the presence of a translocation associated with this family of tumors was confirmed using RT-PCR. Specifically, there were 45 Ewing sarcoma (EWS)-FLI type 1 translocations, four EWS-FLI type 2 translocations, five EWS-ERG translocations, and four less common EWS-FLI variants. Of patients with a confirmed translocation, four were confirmed only after nested RT-PCR techniques were used. In five patients who initially underwent needle biopsy, the diagnosis was confirmed only after open biopsy or repeat needle biopsy was undertaken. Samples from 18 patients were translocation-negative. Of these, seven samples were deemed inadequate for RT-PCR testing as a result of inappropriate tissue handling or the presence of necrotic material. Five patients were found to have a different diagnosis after complete histopathologic and molecular characterization. Six samples remained, in which adequate tissue was obtained with no evidence of a characteristic translocation.
  
  
  CONCLUSIONS
  In apparently translocation-negative samples, close attention should be given to the possibility of an alternative diagnosis, the potential need for nested RT-PCR, and the possibility of an inadequate sample. Strong consideration should be given to the use of open biopsy as opposed to needle biopsy to avoid the need for repeat biopsies and the potential for inaccurate assessment of molecular marker status.
authors.affiliation: Pediatric Oncology Branch , National Cancer Institute. National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: R
authors.initials: R
authors.lastname: Dagher
authors.forename: T A
authors.initials: TA
authors.lastname: Pham
authors.forename: L
authors.initials: L
authors.lastname: Sorbara
authors.forename: S
authors.initials: S
authors.lastname: Kumar
authors.forename: L
authors.initials: L
authors.lastname: Long
authors.forename: D
authors.initials: D
authors.lastname: Bernstein
authors.forename: C
authors.initials: C
authors.lastname: Mackall
authors.forename: M
authors.initials: M
authors.lastname: Raffeld
authors.forename: M
authors.initials: M
authors.lastname: Tsokos
authors.forename: L
authors.initials: L
authors.lastname: Helman
mesh_terms: D000071443:12E7 Antigen; D000293:Adolescent; D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000235:genetics; D001706:Biopsy; D001707:Biopsy, Needle; D001859:Bone Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics / Q000473:pathology; D015815:Cell Adhesion Molecules / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D002880:Chromosomes, Human, Pair 11 / Q000235:genetics / Q000648:ultrastructure; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics / Q000648:ultrastructure; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics / Q000648:ultrastructure; D004273:DNA, Neoplasm / Q000235:genetics; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D008297:Male; D018317:Nerve Sheath Neoplasms / Q000175:diagnosis; D009447:Neuroblastoma / Q000175:diagnosis; D015514:Oncogene Proteins, Fusion / Q000032:analysis* / Q000235:genetics; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D012189:Retrospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012509:Sarcoma / Q000175:diagnosis; D012512:Sarcoma, Ewing / Q000737:chemistry / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics / Q000473:pathology; D014157:Transcription Factors / Q000032:analysis* / Q000235:genetics; D014178:Translocation, Genetic; D009396:Wilms Tumor / Q000175:diagnosis
chemical_list: D000071443:12E7 Antigen; D015703:Antigens, CD; D014408:Biomarkers, Tumor; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules; D004273:DNA, Neoplasm; C450460:EWS-ERG fusion protein, human; C106031:EWS-FLI fusion protein; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D014157:Transcription Factors