RESUMO
In order to optimize the use of ultrasound in the characterization of cystic or nodular lesions, the incidence of simple cysts in the general population, their growth and evolution is discussed considering some follow-up studies. After studying the typical sonographic criteria of simple cyst, we describe the sonographic features of cancer and the incidence of various types of tumors. In such cases radiological evaluations are required and the Bosniak classification is useful in the clinical choice of waiting, more detailed diagnosis or excision of the lesion. The use of the radiological means will decrease when EcocolorDoppler with contrast is widely available. Nevertheless, this technique has already found its way into peculiar fields and in certain cases, it has a higher sensitivity compared to TAC with contrast medium.