[A new prenatal diagnosis case of frontonasal dysplasia]. / Un nouveau cas de diagnostic anténatal de dysplasie frontonasale.

In a 30-year-old patient, the systematic second trimester fetal ultrasound discovered major facial abnormalities suggesting a frontonasal dysplasia (FND). The fetal karyotype was normal but no additional genetic testing was performed. Fetal MRI found an important hypertelorism and an asymmetric cerebral ventricle, with a partially visualized corpus callosum. After several consultations and interviews, the couple made a formal demand for pregnancy interruption, which was approved. Fetal pathologic examination confirmed the diagnosis of FND with no other major associated malformation. This rare pathology results from a midline facial dysgraphia comprising a hypertelorism, a large nasal base, a large clefted nose tip and, a V-shaped hair implantation on the forehead. It often occurs sporadically, of unknown cause, related to a defect in the embryonic nasal capsule development. Syndromic forms have been described with cerebral lesions and possible intellectual deficiency. Consequently, a long and difficult surgical management is necessary, at the expense of poor aesthetic outcome. Seven cases of prenatally diagnosed FND have been reported in the literature, three of which had 3D ultrasound.