How is multilocular cystic nephroma differentiated from Wilms tumor on imaging?

Updated: Mar 04, 2019
  • Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR; Chief Editor: Eugene C Lin, MD  more...
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Multilocular cystic nephroma is synonymous with multilocular renal cyst, cystic Wilms tumor, hamartoma, cystic adenoma, polycystic nephroblastoma, Perlman tumor, and segmental multicystic kidney. These confusing terms indicate the uncertainty about the etiology and about whether the lesion is dysplastic, neoplastic, or hamartomatous. If a Wilms tumor is noted in the walls of this tumor during histologic analysis, it is often treated as a Wilms tumor.

In terms of its morphologic characteristics, a multilocular renal cyst forms a well-defined, bulky mass arising at the lower pole or between poles of an otherwise normal-looking kidney. The mass has a fibrous capsule, which may contain smooth muscle and cartilage. The tumor mass itself has multiloculated, noncommunicating cysts separated by fibrous tissue. The tumor often protrudes into the renal pelvis, and approximately 50% become calcified.

Some researchers have postulated that focal failure of a ureteral branch to organize this segment of the metanephric blastema gives rise to the appearance just described. Undifferentiated mesenchymal tissue in the various constituents of the fibrous capsule supports the postulate that multilocular cystic nephroma is a type of renal dysplasia.

The ultrasound appearance of a multilocular renal cyst is that of a bulky renal mass with a conglomerate of cysts separated by thick septa protruding into the renal pelvis. Calcification is detected in some masses.

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