Severe Holoprosencephaly With Arhinencephaly in A Liveborn Neonate: A Case Report.

Holoprosencephaly (HPE) is a rare congenital brain malformation resulting from incomplete separation of the cerebral hemispheres. It has an estimated prevalence of 1 in 10,000 live births. We report a case involving an 18-year-old primigravida at 28 weeks of gestation. Prenatal ultrasound revealed polyhydramnios, marked hydrocephalus, and absence of the cerebral and cerebellar hemispheres, with preservation of the brainstem. Cesarean delivery was performed, and the female neonate exhibited hypotelorism, arhinia, cleft lip and palate, and a single frontal bony plate (neonatal weight, head circumference, and Apgar scores were not available). The constellation of findings was consistent with severe holoprosencephaly within the alobar-semilobar spectrum with associated arhinencephaly. This case highlights a rare presentation of severe HPE with associated arhinencephaly in a liveborn neonate, occurring in the absence of identifiable risk factors. It underscores the critical role of prenatal imaging in the diagnosis of midline anomalies and the need for thorough postnatal evaluation.