EP05.04: Septopreoptic holoprosencephaly: a postnatal diagnosis… until now

Holoprosencephaly (HPE) is a complex group of brain malformations caused by different degrees of incomplete forebrain division. The mildest form, septopreoptic HPE (SP-HPE), is a rare recently-described condition and is usually a postnatal MRI finding. Herein, we present for the first time a case of isolated SP-HPE diagnosed by fetal neurosonography (NS). A 29-year-old primigravida was referred at 36 weeks due to an unsatisfactory visualisation of the cavum septum pellucidum (CSP). Previous scans were reported as normal. A NS was performed: in the transabdominal axial plane the CSP could not be seen, and the septum pellucidum (SP) appeared thickened. In the transvaginal coronal planes, the SP leaves were undivided, the CSP was not visible, and the fornix was thickened in its anterior portion. In the sagittal planes, the corpus callosum (CC) was normal, with difficult subcallosal region differentiation. The optic chiasma seemed preserved, and no extracerebral anomalies were detected. NS was compatible with SP-HPE. The MRI confirmed these findings and ruled out craniofacial abnormalities. Prenatal diagnosis of SP-HPE is challenging. Case reports and small series have only described cases diagnosed postnatally, mostly associated with other intracranial or endocrine pathologies. Only one case report described a prenatal diagnosis by MRI in the context of a fetus with a thick CC and a labiomaxillary cleft, but no NS was performed. We present the first case of SP-HPE diagnosed by prenatal NS. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.