Evaluation of renal and perirenal leiomyoma on US, CT, and angiography.

The findings of US, CT, and angiography were analyzed in five rare cases of renal and perirenal leiomyoma. The margin of the tumors was shown to be regular by each method, and the tumors were found to be heterogeneous by US and CT. US showed hypoechoic (80%) and mixed echoic (20%) echo patterns. CT revealed soft tissue density with contrast enhancement. Angiography disclosed hypovascularity (25%), and slight vascularity (75%), but no arterial encasement, A-V shunt, or vein invasion. Although no findings specific to the differential diagnosis of malignant tumors were found, benign tumors should be considered when the following signs are detected: (1) a large (more than about 5 cm), well-defined, regular abdominal mass with few symptoms, (2) a heterogenous hypoecho on US, (3) enhanced soft tissue density on CT, and (4) angiography without arterial encasement, A-V shunt, or vein invasion.