[The enlarged kidney in infancy--echographic findings].

Experience in the use of ultrasound to evaluate renal masses during infancy is reported. Ultrasonography revealed hydronefrosis (20 cases), multicystic kidney (5 cases), polycystic kidney disease (3 cases) and neoplasm (4 cases). The differential diagnosis between hydronefrosis and multicystic kidney can be difficult. Hydronefrosis is diagnosed by the demonstration of communication between adjacent fluid-filled spaces.