Open Access

RESIDENT’S CORNER

Incidentally detected nephrogenic rests in the setting of congenital obstructive uropathy

Brian Blew¹, Blair Carpenter², Michael P. Leonard³

1 Department of Urology, University of Ottawa, Ottawa, Ontario, Canada
2 Department of Pathology, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
3 Department of Urology, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada

Canadian Journal of Urology 2002, 9(4), 1595-1598.

Abstract

Purpose: Nephrogenic rests (NR) are clusters of cells similar to renal blastema. NR are frequently seen in kidneys with Wilms' tumor (WT) and are seen with higher frequency in nephrectomy specimens from obstructed and/or multicystic dysplastic kidneys (MCDK) compared to autopsy series of normal kidneys. The significance of NR and their role in tumorigenesis is largely unknown. We report the findings of two cases with NR associated with ureteral ectopy/obstruction and review the relevant literature.
Materials and methods: Two cases of upper pole heminephrectomy associated with ectopic upper pole ureter and resultant hydronephrosis were found to have nephrogenic rests present on pathologic examination. A literature search was done to review recent developments in the understanding of NR and their significance, primarily to guide patient recommendations regarding follow-up.
Results: Recent developments in the understanding of NR include the description of intralobar versus perilobar nephrogenic rests and prognostic considerations associated with each. However, the implications of finding nephrogenic rests in upper pole hemi-nephrectomy specimens associated with ureteral ectopy is not well delineated.
Conclusions: The role of NR in tumorigenesis is still poorly understood. Because of the still undefined relationship with WT we recommend patients with incidentally detected NR be followed with serial abdominal ultrasounds for the first 5 years of life.

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