Wilms tumor: ultrasonic features, pathologic correlation, and diagnostic pitfalls.

The gray-scale ultrasonic features of Wilms tumor are reported with pathologic comparison. The most consistent ultrasonic features are large size, sharp margination, and echogenic heterogeneity. The frequently observed anechoic areas correlated with hemorrhage and necrosis. A rare case of mesoblastic nephroma is included for comparison. Pitfalls in diagnosis are discussed.