Sir.—Several new observations on the natural history of multicystic dysplastic kidneys (MCDKs) may help to deliver Hartman et all from their dilemma. On serial prenatal ultrasonography (US) of six fetal MCDKs, Hashimoto et al2 found that four MCDKs one increased in size, one shrank, and one initially grew larger but subsequently shrank. Only for this last MCDK was a postnatal sonogram reported: the MCDK had become diminutive when the infant was 6 months old.
Pedicelli et al3 described nine infants with MCDKs that either diminished in size or completely disappeared over periods of serial US ranging up to three years. Two of these infants, aged 6 and 9 months, underwent operative flank explorations that failed to disclose any vestiges of cysts or renal tissue. The authors postulated that spontaneous involution of MCDKs might account for some cases of apparent, unilateral renal agenesis. nat
Both reports2,3 suggest that the natural course of
Bowen A. Multicystic Dysplastic Kidneys. Am J Dis Child. 1987;141(6):602-603. doi:10.1001/archpedi.1987.04460060020011