The ultrasound and the MRI features are most consistent with renal angiomyolipoma.

Angiomyolipomas are the most common fat-containing lesions of the kidneys and the most common benign solid renal lesion. The majority of angiomyolipomas are sporadic (80%) and are typically identified in adults (mean age of presentation 43 years), the remaining 20% are seen in association with phakomatoses.