Appearances of renal cysts detected sonographically
Renal cysts are extremely common and are typically incidental. Simple cysts are round or ovoid with anechoic fluid contents, well-demarcated back walls, and posterior acoustic enhancement. Simple cysts do not need any further follow-up. Minimally complicated cysts with a few thin internal septations, small peripheral thin calcification, or internal echoes can be managed with short-term (6-month) follow-up US. In contrast, any cystic lesion with a thickened wall, mural nodularity, multiple or thickened internal septations, or thick, irregular, or amorphous calcification is suspect for a cystic renal neoplasm and may be further evaluated with dedicated contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) of the kidneys.