Mesoblastic nephroma: radiologic-pathologic correlation of 20 cases.

The mesoblastic nephroma is a benign renal tumor that usually appears as a neonatal abdominal mass. The tumor is composed of connective tissue that grows between nephrons and usually replaces most of the renal parenchyma. Radiographic and sonographic images reflect this cellular composition and unique growth pattern. The radiographs of 20 cases of mesoblastic nephroma were correlated with their pathologic findings and are described. Urograms usually demonstrate an intrarenal mass two to seven times larger than the contralateral kidney. Contrast medium is occasionally demonstrated within the tumor and may represent function by nephrons trapped within the mesoblastic nephroma. Sonographic studies correlate well with the gross morphology and may be useful in establishing the relation of the tumor to the kidney. Some neovascularity is present on angiographic examination and most tumors are hypervascular. Prognosis after complete excision is excellent and adjunctive therapy is unnecessary.