The sonographer called this a lesion, and from the answers I got this week, most knew it wasn't a real lesion, but weren't sure what to call it. This is an example of a renal junctional parenchymal defect, which is a normal variant. They will be triangular, echogenic foci in the renal cortex, sometimes with an echogenic tract from the cortex into the renal sinus fat. Generally, they are located between the upper pole and interpolar region of the kidney, but can be seen in the lower pole as well, as they are formed from incomplete embryologic fusion of the renal poles. Oftentimes, it is confused for a renal cortical scar or an angiomyolipoma.
