Desmoplastic small round cell tumor (DSRCT) usually involves peritoneal surfaces extensively with variably-sized irregularly-shaped tumor deposits. Complete surgical excision is often impossible. The treatment consists of a combination of extensive debulking procedure, intraperitoneal/systemic chemotherapy, and radiotherapy with or without stem cell transplantation. Despite intensive therapy, the prognosis is dismal with a 5-yr survival rate of less than 15%. The image shows undifferentiated tumor cells arranged singly or in cords in a background of desmoplastic stroma.