How is renal blastema and/or nephroblastomatosis 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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Renal blastema and nephroblastomatosis are interrelated conditions closely related to Wilms tumors. The persistence of primitive renal blastema beyond infancy (4 mo) is abnormal except in small microscopic rests. Large amounts of primitive blastema remaining in sheets in the cortex or in discrete nodules are termed nephroblastomatosis.

Ultrasonographic detection is possible, but sonography lacks the sensitivity of CT and MRI. On sonograms, the affected kidney may be enlarged and lobulated with multiple hypoechoic areas. Corticomedullary differentiation may be lost.

After such findings are discovered, 3 monthly ultrasound examinations should be performed to detect their progression to a Wilms tumor. Rapid growth of any of the hypoechoic rests suggests progression. Antenatal detection is possible when sonograms reveal bilateral nephromegaly with normal renal echogenicity. However, foci of calcification may be associated with polyhydramnios, and they can occur as a part of a familial condition.

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