Small round cell tumor with biphenotypic differentiation and variant of t(21;22)(q22;q12)

Pediatr Dev Pathol. Jul-Aug 2001;4(4):391-6. doi: 10.1007/s10024001-0005-6.


A 14-year-old boy presented with a soft tissue swelling on the outer aspect of his left upper arm. Examination of the tumor by light microscopy showed a small round cell tumor with a rare focus of myogenic differentiation. Myogenic differentiation was confirmed on ultrastructural examination by immunohistochemistry and reverse transcriptase polymerase chain reaction (RT-PCR). Conventional G-banding and fluorescent in situ hybridization (FISH) demonstrated a complex variant of t(21;22)(q22;q12). By RT-PCR, the EWS-ERG fusion transcript was defined as type 9e. This tumor was unusual in that it showed characteristics of myogenic and neural differentiation, and contained a rearrangement of the EWS gene consistent with a diagnosis of Ewing's sarcoma. This supports the hypothesis that a class of biphenotypic childhood sarcomas, with features of myogenic and neural differentiation, exists that may be related to the Ewing's sarcoma family of tumors.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Bone Neoplasms / genetics
  • Bone Neoplasms / metabolism
  • Bone Neoplasms / pathology*
  • Cell Transformation, Neoplastic
  • Chromosome Banding
  • Chromosomes, Human, Pair 21*
  • Chromosomes, Human, Pair 22*
  • DNA, Neoplasm / analysis
  • Diagnosis, Differential
  • Dissection
  • Heterogeneous-Nuclear Ribonucleoproteins
  • Humans
  • In Situ Hybridization, Fluorescence
  • Male
  • Micromanipulation
  • Phenotype
  • RNA-Binding Protein EWS
  • Reverse Transcriptase Polymerase Chain Reaction
  • Ribonucleoproteins / metabolism
  • Sarcoma, Ewing / genetics
  • Sarcoma, Ewing / metabolism
  • Sarcoma, Ewing / pathology*
  • Sarcoma, Small Cell / genetics
  • Sarcoma, Small Cell / metabolism
  • Sarcoma, Small Cell / pathology*
  • Translocation, Genetic / genetics*


  • DNA, Neoplasm
  • Heterogeneous-Nuclear Ribonucleoproteins
  • RNA-Binding Protein EWS
  • Ribonucleoproteins