Renal angiomyolipoma: growth followed up with CT and/or US.

Abstract

Multiple AMLs show more growth than solitary AMLs.

Radiologic Imaging of Renal Masses

“…On computerized tomography AML are generally of low Hounsfield unit attenuation value (-20 HU and less) in the unenhanced phase [37,144], and have not been found to be associated with calcification as may be the case with renal cell carcinoma. [37,145] Aneurysmal dilation is found in 50% of AMLs when they are visualized by angiography and can also suggest the diagnosis [37], but irregular vascularity can be seen in cases of renal cell carcinoma as well.…”

“…In 14% of AMLs, fat cannot be identified with CT, presumably related to a reduced proportion of mature adipose tissue, and a definite diagnosis cannot be made. [37,146] Milner et al noted that cases involving less than 25% fat/high power field on histologic analysis correlated with computerized tomographic findings where fat usually was not noted. [147] MRI However, newer generation CT scanners with improved spatial resolution are also useful for detection small amounts of gross fat not detected on MRI.…”

“…More than 50% of renal AML are now found incidentally due to more prevalent use of abdominal imaging for the evaluation of a wide variety of nonspecific complaints. [37] On rare occasions these neoplasms may display unusual behavior. Benign AML involving the renal vein and vena cava as a tumor thrombus has been reported.…”

“…The typical but not diagnostic finding of AML on ultrasonography is a well-circumscribed, highly echogenic lesion, often associated with shadowing. [37,25] The finding of shadowing should suggest an AML rather than a small, echogenic RCC, which rarely shadows [25]. In terms of differentiation and characterization of solid renal masses using ultrasonography, the presence of shadowing, a hypoechoic rim, and intratumoral cysts are thought to be important findings that may help distinguish angiomyolipomas from other solid lesions, namely renal cell carcinoma.…”

“…[37,145] Aneurysmal dilation is found in 50% of AMLs when they are visualized by angiography and can also suggest the diagnosis [37], but irregular vascularity can be seen in cases of renal cell carcinoma as well. However, fat poor angiomyolipomas may not show such features.…”