Agnathia-otocephaly complex diagnosed by prenatal ultrasound: a case report

Agnathia-otocephaly complex (AOC) is a rare and complex craniofacial malformation characterized by mandibular hypoplasia or agnathia, auricular fusion (synotia), and microstomia with oroglossal hypoplasia or aglossia. It can occur alone or in combination with forebrain anomalies and cardiac malformations and has an extremely poor prognosis. Here, we report a case of AOC diagnosed by systemic fetal screening at a gestational age of 25+4 weeks. Ultrasound revealed that the S-curve formed by the normal lower jaw and lower lip had disappeared, the lower jaw and mandible were invisible, the mouth was extremely small, and the oral fissure was "pinhole-shaped". There was a cone-shaped perioral bulge. Both ears were located in the front side of the neck, and the right foot was inverted. Excessive amniotic fluid was observed. The absence of a mandible was confirmed on X-ray examination after induced abortion. Specimen observation showed that the ear positions were extremely low, and both earlobes were connected in the front side of the neck. It was particularly challenging to identify the development of the mandible and locate auricles during prenatal ultrasound diagnosis, and the prenatal diagnosis of AOC was confirmed by combining two-dimensional and three-dimensional ultrasound in our current case.