Lucas was born at 37 weeks of gestation, with a birth weight of 2.8 kg, by Caesarean section for maternal fever and rupture of the membrane. He cried immediately after birth and was noted to have respiratory distress. Initial workup showed a raised white cell count of 20 × 109/L, and maternal high vaginal swab grew Group B streptococcus colonisation. Lucas was managed as suffering from a perinatal infection with intravenous antibiotics, and a chest X-ray was taken (Fig. 22.1). This challenging case begins with a common perinatal presentation, where subsequent physical examination reveals bilaterally enlarged kidneys. What is the diagnosis and how can Lucas's condition be managed?