DES and desmoplastic small round cell tumor: Because most patients develop DSRCT within cavities lined with mesothelial cells and because tumor cells show positive immunohistochemical reactions for epithelial and mesenchymal antigens, such as Desmin and WT1, DSRCT is speculated to originate from mesothelial or submesothelial cells.13) The incidence of DSRCT does not differ significantly between races, but it is predominantly male, with a male-to-female ratio of approximately 3–5:1, and it tends to occur more frequently in younger people.14) DSRCT is characterized by a poor prognosis with 15% overall survival at 5 years.15)