Multicystic dysplastic kidney (MCDK) is a congenital maldevelopment in which the renal cortex is characteristically replaced by numerous cysts of multiple sizes. MCDK presenting as a single predominant large cyst in morphology is less common. We report on the prenatal imaging findings and perinatal management of a fetus with MCDK unusually presenting as a single predominant large cyst, erroneously interpreted as a severe fetal hydronephrosis. Details of the perinatal history, radiological evaluation, morphological characteristic, and clinical aspect of this case are presented. We also discuss a few studies addressing the sensitivity of magnetic resonance urography for the prenatal diagnosis of MCDK.
