According to literature the primary retroperitoneal malignant pathology is rare, representing less than 0.5% of all malignancies. In spite of its low incidence, this pathology often proves challenging in terms of diagnosis and treatment. The most com¬mon retroperitoneal malignancy is represented by lymphoma that accounts for approximately 33 % of the retroperitoneal malignancies. Other frequent retroperitoneal tumors are sarcomas: leiomyosarcomas and malignant fibrous histiocytoma (in order of incidence). We have analyzed the existing data regarding the most common primary retroperitoneal tumors in order to realize a brief classification and their differential diagnosis considering their clinical, imagistic, histopathological and molecular characteristics. The technological developments that have been made over the years in terms of imaging investigations, as well as in biomelecular and cytogenetic studies have offered new possibilities for of assessing a retroperitoneal mass in order achieve more precise informations that can guide physicians to better distinguish between different types of retroperitoneal tumors and therefore their therapeutical protocol. liposarcomas,
Retroperitoneal tumors grow quietly and are generally large in size, more than half of them being larger than 20 cm at the time of diagnosis. They usually present several therapeutic challenges because of their rarity, relative late presentation and anatomical location, often in close relationship with several important structures in the retroperitoneal space. Due to intimate relationships with vital organs in retroperitoneum, extensive surgery with en bloc resection of the involved organ is often required, most frequently the kidneys, followed by colon, pancreas and spleen. Malignant tumors have a poor prognosis, the most significant factors regarding survival rates being delayed diagnosis, high histological grade, inoperability due to invasion into vital organs, and a positive surgical border.
Renal angiomyolipomas (AML) are the most common benign renal tumors. By containing an important amount of fat tissue they are easily identifiable on CT and MRI images, thus no biopsy should be needed for a diagnosis. However there is a small percentage of AMLs that have very little fat tissue and are very difficult to differentiate from renal cell carcinoma. Along fat tissue, they also contain smooth muscle and blood vessels. Renal AMLs can occur as a sporadic finding, or more frequently in association with tuberous sclerosis complex (TSC) or pulmonary lymphangioleiomyomatosis (LAM). These tumors are usually an incidental finding on imaging tools, but sometimes a serious presentation is rupture and hemorrhage, which can easily evolve to shock. Therapeutical management vary from active surveillance to surgical removal, and it needs to be individualized for every patient and according to the clinical presentation.
