(A) Sonographic image of the right kidney demonstrates marked renal atrophy (arrow). Multiple simple-appearing cysts (asterisks) are seen in the kidney. (B) Sonographic image of the left kidney also demonstrates marked renal atrophy. Some cysts are seen. At the upper pole, there is a solid mass (arrow). (C) T2-weighted magnetic resonance imaging through the area of the mass confirms the presence of the mass (arrow) and shows it to be a solid lesion that is mildly hyperintense to muscle.