Prominent column of Bertin

Normal anatomical variant: hypertrophied cortical tissue extending between pyramids into the renal sinus (Persistent fetal lobulation pattern).
Can indent or splay the renal sinus, often at the junction of upper and mid pole; usually continuous with cortex in all planes.
Isoechoic/isodense to cortex, normal enhancement; no cortical bulge externally.
Key exam angle: distinguished from a mass by continuity with cortex, normal corticomedullary differentiation, and lack of calyceal distortion/destruction.