Abstract
Primary retroperitoneal neoplasms account for only 0.1–0.2% of all malignancies. Retroperitoneal neoplasms are most commonly mesodermal, neurogenic or lymphatic in origin, with lymphoma, liposarcoma, leiomyosarcoma and malignant fibrous histiocytoma the vast majority of malignant primary retroperitoneal tumors. Although the radiographic features of retroperitoneal neoplasms often overlap, certain CT characteristics, pattern of spread and specific tumor prevalence among different demographic groups can help suggest the tumor type. CT is used to diagnosis and assess the size and extent of retroperitoneal tumors, as well as assess the involvement of organs and vasculature with resection in mind.