Prenatal ultrasonography of autosomal dominant polycystic kidney disease mimicking recessive type: case series.

BACKGROUND: Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited renal disease. This pathology has been increasingly diagnosed in utero and several sonographic patterns are well described in the literature. OBJECTIVE: To present a series of fetuses with an unusual imaging pattern of ADPKD, mimicking autosomal recessive polycystic kidney disease (ARPKD). MATERIALS AND METHODS: We retrospectively reviewed second-line ultrasound (US) scans performed for suspicion of fetal kidney pathology between 2006 and 2018. Inclusion criteria were (1) proven ADPKD on the basis of a known family history and/or of genetic testing and (2) US features suggestive of ARPKD. We recorded the clinical, imaging, genetic and pathological findings in cases with pregnancy termination. RESULTS: Three out of 12 patients with proven ADPKD diagnosed in utero presented with US features suggestive of ARPKD. Furthermore, an additional patient observed at another institution was added to the series. History of familial ADPKD was present in three cases. US showed enlarged kidneys with increased cortical echogenicity, decreased corticomedullary differentiation, multiple medullary cysts and decreased amniotic fluid in all four cases. Pregnancy was terminated in two cases (histology confirmed features in keeping with ADPKD), one premature neonate died (histology in progress) and one child is alive. Genetic testing showed a homozygous mutation of the PKD1 gene in two patients, a heterozygous mutation of the PKD1 gene in one patient and was not performed in the remaining patient. CONCLUSION: This series describes an unusual sonographic prenatal presentation of ADPKD, not yet well described in the radiologic literature, mimicking ARPKD.