Is it possible to differentiate AMLs and RCCs sonographically?
AMLs are benign renal neoplasms composed of varying amounts of fat, smooth muscle, and blood vessels. An AML is typically hyperechoic compared to the renal parenchyma on US. However, this hyperechoic appearance is not completely diagnostic for an AML, because small (<3 cm) RCCs may also be hyperechoic.
The presence of posterior acoustic shadowing without calcification is suggestive of an AML, whereas presence of internal calcification or cystic regions favors an RCC. However, in most cases, CT or MRI is indicated to further characterize a hyperechoic renal mass.