Computerized tomography characteristics that differentiate angiomyolipomas from liposarcomas in the perinephric space

Purpose: We performed a retrospective study to determine computerized tomography (CT) findings associated with perinephric angiomyolipomas or perinephric liposarcomas. Materials and Methods: During the last 7 years 6 patients with perinephric angiomyolipoma and 12 with perinephric liposarcoma were seen at our hospital. Two radiologists who were blinded to the pathological diagnosis retrospectively evaluated the CT characteristics of perinephric angiomyolipoma and perinephric liposarcoma. The relationship of each CT characteristic with tumor type was compared using Fisher's exact test. Results: The CT characteristics of perinephric angiomyolipoma were intratumoral linear vascularity (p = 0.001), aneurysmal dilatation (p = 0.025), bridging vessel sign (p = 0.005), hematoma (p = 0.025), beak sign (p = 0.001) and discrete intrarenal fatty tumors (p = 0.025). The CT characteristic of perinephric liposarcoma was a nonfatty soft tissue mass (p = 0.005). There was no significant difference in the presence of calcifications in both groups. Conclusions: This retrospective study suggests that analysis of CT characteristics (linear vascularity, aneurysmal dilatation, bridging vessel sign, hematoma, beak sign and discrete intrarenal fatty tumors) may help to differentiate perinephric angiomyolipoma from perinephric liposarcoma.