title: Atypical Ewing sarcoma breakpoint region 1 fluorescence in-situ hybridization signal patterns in bone and soft tissue tumours: diagnostic experience with 135 cases.
abstract: OBJECTIVE
  Recurrent Ewing sarcoma breakpoint region 1 (EWSR1) gene rearrangements characterize a select group of bone and soft tissue tumours. In our routine diagnostic practice with fluorescence in-situ hybridization (FISH), we have occasionally observed EWSR1 gene rearrangements in tumours not associated classically with EWSR1 translocations. This study aimed to review our institutional experience of this phenomenon and also to highlight the occurrence of unusual EWSR1 FISH signals (i.e. 5' centromeric region or 3' telomeric region signals) that do not fulfil the published diagnostic criteria for rearrangements.
  
  
  RESULTS
  Using an EWSR1 break-apart probe, we performed FISH assays on formalin-fixed paraffin-embedded tissue sections from 135 bone and soft tissue specimens as part of their routine diagnostic work-up. EWSR1 gene rearrangements were identified in 51% of cases, 56% of which also showed an abnormal FISH signal pattern (in addition to classically rearranged signals). However, atypical FISH signals were present in 45% of the non-rearranged cases. In addition, we observed tumours unrelated to those described classically as EWSR1-associated that were technically EWSR1-rearranged in 6% of cases. Borderline levels of rearrangement (affecting 10-30% of lesional cells) were present in an additional 17% of these cases.
  
  
  CONCLUSIONS
  While our study confirmed that FISH is a sensitive and specific tool in the diagnosis of EWSR1-associated tumours, atypical FISH signals and classical rearrangement in entities other than EWSR1-associated tumours can occur. Therefore, it is essential that the FISH result not be used as an isolated test, but must be evaluated in the context of clinical features, imaging, pathological and immunohistochemical findings.
authors.affiliation: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.
authors.forename: A Cristina
authors.initials: AC
authors.lastname: Vargas
authors.affiliation: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.
authors.forename: Christina I
authors.initials: CI
authors.lastname: Selinger
authors.affiliation: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.|Douglass Hanly Moir Pathology, Macquarie Park, NSW, Australia.
authors.forename: Laveniya
authors.initials: L
authors.lastname: Satgunaseelan
authors.affiliation: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.|Sydney Medical School, University of Sydney, Sydney, NSW, Australia.|School of Medicine, University of Western Sydney, Campbelltown, NSW, Australia.
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Cooper
authors.affiliation: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.|Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
authors.forename: Ruta
authors.initials: R
authors.lastname: Gupta
authors.affiliation: Chris O'Brien Lifehouse, Camperdown, NSW, Australia.|Orthopaedic Surgery, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.|Macquarie University, North Ryde, NSW, Australia.|The Children's Hospital, Westmead, NSW, Australia.|North Shore Private Hospital, St Leonards, NSW, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Stalley
authors.affiliation: Radiology/Medical Imaging, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.
authors.forename: Wendy
authors.initials: W
authors.lastname: Brown
authors.affiliation: Radiology/Medical Imaging, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.
authors.forename: Judy
authors.initials: J
authors.lastname: Soper
authors.affiliation: Radiology/Medical Imaging, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.
authors.forename: Julie
authors.initials: J
authors.lastname: Schatz
authors.affiliation: Chris O'Brien Lifehouse, Camperdown, NSW, Australia.|Orthopaedic Surgery, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.|Macquarie University, North Ryde, NSW, Australia.|The Children's Hospital, Westmead, NSW, Australia.|North Shore Private Hospital, St Leonards, NSW, Australia.
authors.forename: Richard
authors.initials: R
authors.lastname: Boyle
authors.affiliation: The Kinghorn Cancer Centre, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.
authors.forename: David M
authors.initials: DM
authors.lastname: Thomas
authors.affiliation: Sydney Medical School, University of Sydney, Sydney, NSW, Australia.|Chris O'Brien Lifehouse, Camperdown, NSW, Australia.
authors.forename: Martin H N
authors.initials: MH
authors.lastname: Tattersall
authors.affiliation: Sydney Medical School, University of Sydney, Sydney, NSW, Australia.|Chris O'Brien Lifehouse, Camperdown, NSW, Australia.
authors.forename: Vivek A
authors.initials: VA
authors.lastname: Bhadri
authors.affiliation: Douglass Hanly Moir Pathology, Macquarie Park, NSW, Australia.
authors.forename: Fiona
authors.initials: F
authors.lastname: Maclean
authors.affiliation: Douglass Hanly Moir Pathology, Macquarie Park, NSW, Australia.|Macquarie University, North Ryde, NSW, Australia.|School of Medicine, Notre Dame University, Sydney, NSW, Australia.
authors.forename: S Fiona
authors.initials: SF
authors.lastname: Bonar
authors.affiliation: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.|Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Scolyer
authors.affiliation: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.|Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
authors.forename: Rooshdiya Z
authors.initials: RZ
authors.lastname: Karim
authors.affiliation: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.|Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
authors.forename: Stanley W
authors.initials: SW
authors.lastname: McCarthy
authors.affiliation: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.
authors.forename: Annabelle
authors.initials: A
authors.lastname: Mahar
authors.affiliation: Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.|Sydney Medical School, University of Sydney, Sydney, NSW, Australia.|The Kinghorn Cancer Centre, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia.
authors.forename: Sandra A
authors.initials: SA
authors.lastname: O'Toole
mesh_terms: D001859:Bone Neoplasms / Q000235:genetics*; D002148:Calmodulin-Binding Proteins / Q000235:genetics*; D015321:Gene Rearrangement; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins / Q000235:genetics*; D012983:Soft Tissue Neoplasms / Q000235:genetics*
chemical_list: D002148:Calmodulin-Binding Proteins; C500986:EWSR1 protein, human; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins
keywords: EWSR1-associated tumours; fluorescence in-situ hybridization; rearrangement