Pediatrics New Born Infants 60f472dd Most common cause of abdominal mass in neonates is? A Neuroblastoma B Multicystic dysplastic kidney C Polycystic kidney D Umbilical hernia High-Yield Explanation b. Multicystic dyspiastic kidney(Ref: Nelson's 20/e p 2513)Multicystic dyspiastic kidneyQ is the most common cause of abdominal mass in a neonate.