23 - Cystic renal masses

Abstract

Cystic lesions in the kidneys are common, and multiple imaging modalities are often used to fully characterize them. A simple cyst has sonographic features of thin, imperceptible walls, posterior acoustic enhancement, and anechoic contents. On computed tomography (CT), a simple cyst has attenuation of water. On magnetic resonance imaging, a simple cyst will be hyperintense on T2-weighted imaging and have no enhancing walls, septations, or solid components. The Bosniak criteria are widely used to classify cystic renal lesions into benign (I and II), safe-to-follow (IIF), and surgical (III and IV). Certain benign cystic masses (such as cystic nephroma) can be indistinguishable from cystic renal cell carcinoma (RCC) or cystic Wilms tumor in a child, and therefore must be treated surgically when feasible. Certain conditions, such as autosomal dominant polycystic kidney disease, can lead to numerous cystic masses that replace normal renal parenchyma and lead to hypertension and renal failure. Long-term dialysis increases the likelihood of RCC. Von Hippel-Lindau is a syndrome with autosomal dominant inheritance with high risk of malignancy in multiple organ systems. Patients are at increased risk of RCC in addition to adrenergic tumors (pheochromocytoma), hemangioblastomas, and neuroendocrine pancreatic tumors.