A baby girl is born at term to a 34-year-old multigravid mother by cesarean delivery for decreased fetal movement. Prenatal laboratory studies are unremarkable, and prenatal ultrasounds done at 10, 12, 20, 28, and 30 weeks are all normal. Delivery is complicated by meconium-stained amniotic fluid, for which the infant requires oral suctioning and some blow by oxygen. Apgars are 8 and 9 at 1 and 5 minutes. The infant is sent to the general care nursery. On examination, the birth weight is 2.9 kg (25%), length is 49 cm (50%), and head circumference is 36 cm (95%). Otherwise, her examination is unremarkable. On the second day after birth, the infant is reported by the mother to be sleepier and not feeding as well. Her exam is notable for a tense anterior fontanelle, widely spaced posterior sutures, and head circumference increased to 37 cm (>95%). A head ultrasound is performed and shows a large echogenic mass measuring 9 cm in the left cerebral hemisphere, with resultant obstructive hydrocephalus of the right lateral ventricle and midline shift to the right (Fig 1). Head computed tomography scan shows a large left hemisphere hemorrhagic mass lesion, concerning for mass versus hemorrhage. The infant is transferred to the NICU for further care. Figure 1. Head ultrasound image demonstrating a large echogenic mass in the left cerebral hemisphere measuring up to 9 cm. Mass/hemorrhage causing obstructive hydrocephalus of the right lateral ventricle and midline shift to the right. In the NICU, the infant is noted to have apnea and bradycardia, severe enough to require intubation. Sluggish pupils and intermittent tonic posturing of the upper extremities are also …