<prompt> Which of the following is the most common retro peritoneal sarcoma ?LiposarcomaLeomyo sarcomaFibrosarcomaNeural sheath sarcoma  <response>: Retroperitoneal sarcomas account for 0.1-0.2 of all malignant tumours and about 15 of all sarcomas. Liposarcoma is the most common type of retroperitoneal sarcoma 41, followed by leiomyosarcoma, malignant fibrous histiocytoma, fibrosarcoma and other undifferentiated sarcomas 