<prompt> A 3-week-old child presents with an abdominal mass. What is the most common cause of the presentation?NeuroblastomaWilms tumorMulticystic dysplastic kidneyDistended bladder  <response>: c. Multicystic dysplastic kidneyRef: Nelsons 20e p 2555Multicystic dysplastic kidney is the most common cause of an abdominal mass in the newborn, but the majority are nonpalpable at birth. 