Within cortex of mid pole of the right kidney, there is a 6x7x5mm echogenic lesion with no posterior shadowing. what does this mean? stone or tumor?

Not likely a stone: The lack of shadowing generally means that it is not a Stone. Is it a complex cyst or a tumor or a benign mass? That depends on a myriad of factors. While doctors may have their suspicions, the proof is in a biopsy. If the pt is otherwise healthy, it may not be worthwhile to biopsy an incidental lesion. TTYD or use HealthTap Prime. Good luck!