Nephrogenic rest within a lipomyelomeningocele in a patient with unilateral renal agenesis.

Nephrogenic rests (NR) are foci of embryonal renal tissue that persist beyond the normal period of renal morphogenesis. They are commonly found in kidneys bearing Wilms tumor but may also rarely occur in different locations. Nephrogenic rests have been reported in the lumbosacral area in a total of nine cases, including our case. Of the nine cases, only one case prior to ours showed agenesis of one kidney in association with the NR. We report a 2-year-old female with a lipomyelomeningocele containing NRs and agenesis of the right kidney and discuss the molecular genetic basis of lumbosacral NR.