Identification of a novel translocation producing an in-frame fusion of TAF15 and ETV4 in a case of extraosseous Ewing sarcoma revealed in the prenatal period

Virchows Arch. 2022 Oct;481(4):665-669. doi: 10.1007/s00428-022-03335-2. Epub 2022 May 9.

Abstract

Ewing sarcoma (ES) is a highly malignant round cell sarcoma, characterized by gene fusion involving FET (FUS, EWSR1, TAF15) and ETS family genes, respectively. The involvement of the EWSR1 gene has been reported in approximately 90% of cases of ES, with the EWSR1::FLI1 fusion being the most frequent. We report the case of a newborn with a localized soft tissue paravertebral neoplasm diagnosed prenatally. Histopathology and immunophenotype were consistent with a CD99 + , NKX2.2 + undifferentiated round cell sarcoma (URSC); whole-exome RNA-sequencing demonstrated an undescribed in-frame TAF15::ETV4 fusion transcript, while consensus clustering analysis showed high transcriptomic proximity to the ES group. Given clinical context, high tumor chemosensitivity to ES conventional drugs, morphological characteristics, nature of the fusion partners involved, and high transcriptomic proximity to bona fide ESs, this case may represent a new genetic variant of ES.

Keywords: ETV4; Ewing sarcoma; Pediatric; TAF15; TAF15::ETV4; URSC.

Publication types

  • Case Reports

MeSH terms

  • Gene Fusion
  • Humans
  • Infant, Newborn
  • Oncogene Proteins, Fusion / genetics
  • Proto-Oncogene Proteins c-ets / genetics
  • RNA
  • RNA-Binding Protein EWS / genetics
  • Sarcoma* / genetics
  • Sarcoma, Ewing* / diagnosis
  • Sarcoma, Ewing* / genetics
  • Sarcoma, Ewing* / pathology
  • Soft Tissue Neoplasms* / pathology
  • TATA-Binding Protein Associated Factors* / genetics
  • Translocation, Genetic

Substances

  • ETV4 protein, human
  • Oncogene Proteins, Fusion
  • Proto-Oncogene Proteins c-ets
  • RNA-Binding Protein EWS
  • TAF15 protein, human
  • TATA-Binding Protein Associated Factors
  • RNA