Abstract
This chapter presents the role of multidetector computed tomography (MDCT) in conservative treatment of renal cell carcinoma. Approximately 10% of renal cell carcinomas manifest primarily as a fluid-filled unilocular or multiloculated cystic mass. MDCT play an important role in differentiating these renal cell carcinomas from simple renal cysts and, more importantly, from benign renal cysts complicated with hemorrhage, infection, inflammation, or ischemia. On MDCT, either cystic renal cell carcinomas or benign complicated renal cysts are characterized by one or more of these features: calcification, high attenuation at unenhanced CT scan, septations, multiple locules, enhancement, wall thickening, and nodularity. Papillary renal cell carcinoma, which probably originates from the distal convoluted tubule, stands for 7-14% of all renal cell carcinomas. On MDCT these tumors are characterized by weak, mostly homogeneous enhancement and calcifications are relatively more common in 32% of cases. Collecting duct carcinoma is a rare type of renal cell carcinoma that originates from the collecting duct (of Bellini). It affects younger patients and is associated with aggressive regional and distant spread. These tumors are characterized on MDCT by medullary location, weak and heterogeneous enhancement, involvement of the renal sinus, infiltrative growth, preserved renal contour, and presence of a cystic component. MDCT differentiates renal neoplasms that require surgical resection, including renal cell carcinoma, transitional cell carcinoma, and oncocytoma, from renal neoplasms that do not routinely require surgical resection, such as angiomyolipoma, lymphoma, and metastatic disease. The renal cell carcinomas rarely contain intratumoral fat and calcifications, therefore meticulous evaluation of all solid renal masses, using an unenhanced dedicated MDCT examination, for the presence of fat is mandatory to avoid misdiagnosing an angiomyolipoma as renal cell carcinoma.