[Renal cell carcinoma- diagnosis by computed tomography]

In approximately 10% of cases, renal cell carcinoma (RCC) could present as a fluid- filled cystic mass. There are three mechanisms by which RCC may become cystic: extensive cystic necrosis, intrinsic cystic growth and origin from the epithelium lining a simple renal cyst. Simple renal cysts are very common. Uncommonly these cysts are complicated by hemorrhage, infection and possibly ischemia. The goal of the radiologist in evaluating these cystic lesions is to distinguish malignant neoplastic cystic masses from non-neoplastic complicated cysts so that appropriate management can be undertaken: RCC is best treated by surgical excision while non-neoplastic complicated cysts do not require surgery. The radiologic findings in these cystic masses which must be carefully evaluated include calcification, abnormal density, septations, nodularity, wall thickening and enhancement.