Desmoplastic small round cell tumor (DSRCT) is a rare tumor typically involving peritoneum. The concept of DSRCT as a distinct tumor has been strengthened by association with a specific chromosomal abnormality, t(11;22)(p13;q12) that involves the EWSR1 and WT1 genes. EWSR1 encodes the EWS protein which is a member of the FET family of RNA-binding proteins, while WT1 encodes a zinc-finger transcription factor. Several transcriptional targets of the EWSR1-WT1 chimera have been identified such as Platelet Derived Growth Factor A (PDGFA), IL2 receptor-beta, Myeloid Leukemia Factor 1 (MLF1) or Insulin-like Growth Factor 1 receptor (IGF1-R). Somatic MET and PIK3CA mutations have also been identified.
