Radiologic Approach to Solid and Cystic Renal Masses

Renal mass-like lesions are ubiquitous. Fortunately, most are benign. The most common renal mass is a benign cyst. In fact, pathologic investigations have shown that approximately one-half of the population over the age of 50 has one or more renal cysts [1]. Computed tomography (CT) investigations show that one-quarter to one-third of patients over 50 years of age has at least one cyst [2]. Renal cell carcinoma (RCC) is most commonly identified because of the widespread use of cross-sectional imaging in the abdomen, either by CT or ultrasound (US), usually performed for a non-renal complaint [3]. With advances in CT and US technology, radiologists are detecting more masses and characterizing cysts as small as 5 mm [4]. Similarly, small solid masses may be also characterized with confidence.