Wilms' tumor versus neuroblastoma: usefulness of ultrasound in differentiation.

Wilms' tumor and neuroblastoma represent the two most common abdominal malignancies of childhood. Sonograms of 46 cases of neuroblastoma and Wilms' tumor were retrospectively reviewed. Wilms' tumor is usually fairly evenly echogenic or evenly echogenic, with discrete holes corresponding to areas of cystic necrosis. Neuroblastoma is usually quite heterogeneous, with irregular hyperechoic areas intermixed with less echogenic areas. A correct diagnosis was made in 23 of 26 "unknown" cases of Wilms' tumor and neuroblastoma on the basis of sonographic findings alone. This series included one case of Wilms' tumor arising outside the kidney and one case of neuroblastoma invading the kidney. Sonograms show relatively distinct patterns for the two tumors based on textural differences and will probably be most useful in those equivocal cases in which the site of tumor origin is uncertain.