This cases illustrates a renal cyst with non-enhancing high-attenuation likely due to proteinaceous or hemorrhagic contents. It measures less than 3 cm and does not have any imaging worrisome features, in keeping with a Bosniak 2 category. No further imaging is required. 

The Bosniak classification system for CT evaluation of renal cysts is helpful in determining both malignant risk and required follow up / treatment.