[A kidney tumor as an incidental ultrasound finding].

Renal cell carcinomas used to have a poor prognosis due to the absence of early symptoms. The advent of ultrasound examination increased the rate of incidentally detected renal cell carcinomas from 10% to more than 50%. Incidental carcinomas are smaller than symptomatic ones, have a lower T-stage and lower grading, and patients are 8 years younger on average. This leads to a better prognosis of incidental renal cell carcinomas with an average survival rate of up to 90% after 1 and 5 years. In early detection of renal cancer ultrasound is more effective than urography. Screening by ultrasound is too expensive. The incidence of small renal cell carcinomas with a diameter up to 3 cm is increasing. These tumours are often hyperechoic and can be differentiated from angiomyolipomas by a characteristic anechoic rim.