Three-dimensional sonographic findings of diprosopus: a case report and literature review

Abstract

Background: Diprosopus is one of the rarest anomalies. It typically manifests as bilateral alterations and often involves anomalies within the cranial structures. In this report, we present a case of a fetus with diprosopus diagnosed prenatally. Along with reviewing relevant literature on prenatal ultrasound diagnosis of diprosopus, we aim to raise awareness of its ultrasound characteristics.

Case presentation: We report a case of craniofacial and intracranial abnormalities detected during a 26-week ultrasound examination. Two-dimensional ultrasound (2D ultrasound) demonstrates significant increases in head circumference, widening of the interocular distance, and abnormal echo patterns in the facial structure. Three-dimensional ultrasound (3D ultrasound) revealed the presence of three eye sockets (the lateral eye sockets contained eyeballs, while the central region exhibited fusion without visible eyeballs), two noses, and two mouths, with no abnormalities observed in other areas. The ultrasound findings suggested diprosopus. Following risk counseling at the prenatal diagnosis center, the pregnant woman decided to induce labor. The newborn passed away thirty minutes after delivery. The facial features of the newborn were consistent with the 3D ultrasound imaging, and the appearance of the trunk and limbs was normal. Both CT and MRI scans confirmed the diagnosis of diprosopus.

Conclusion: The prenatal 2D ultrasound revealed intracranial and facial abnormalities in the fetus. 3D ultrasound imaging clearly displayed the facial duplication anomalies, highlighting the advantages of 3D ultrasound in diagnosing diprosopus. We hope to raise awareness of this rare condition and provide insights into prenatal ultrasound diagnosis through this case.

Keywords: Case report; Diprosopus; Prenatal ultrasound examination; Three-dimensional ultrasound imaging.

Fig. 1

The coronal section through the thalamus demonstrates intact cranial bones, prominent and enlarged frontal lobes, and an indistinct corpus callosum. An anechoic area is observed at the midline of the brain as indicated by the arrow. (b)This image reveals abnormal widening of both orbits (OR: Orbit) with abnormal echogenicity between them as indicated by the arrow. (c) Three-dimensional surface imaging of the facial features confirms diprosopus, the fused orbits are indicated by the yellow arrow, and the fused auricles are indicated by the blue arrow (E: Eye; N: Nose; M: Mouth)

Fig. 2

The specimen post-abortion shows (a) no abnormalities in the trunk and limbs, and (b) diprosopus in the facial features

Fig. 3

Postnatal MRI images of this case. (a) T1-weighted imaging reveals fusion of the bilateral maxillofacial bones as indicated by the arrow. (b) MRI T2-weighted imaging shows bilateral enlargement of the frontal lobes, widening of brain gyri, and an increased angle between the anterior edges of the lateral ventricles (F: Frontal Lobe). (c) T2-weighted imaging shows widening of the cranial bones in the frontal region, absence of eyeballs in the fused central eye region as indicated by the arrow, and two paranasal sinuses (E: Eye; PNS: Paranasal Sinuses). (d) T2-weighted imaging displays normal symmetric frontal and parietal lobes, brainstem, and fourth ventricle. (BS: Brain Stem; P: Parietal Lobe; 4 V: Fourth Ventricle)

Fig. 4

Postnatal CT images of this case (a) show two fully developed cochleae (C: Cochlea). (b) shows fusion of the two sphenoid bones, as indicated by the arrow in the middle (Sph: Sphenoid Bone). (c) CT three-dimensional imaging reveals the fusion of two nasal bones, two fused maxillae (indicated by the arrows) and two fused mandibles (indicated by the blue arrows), as well as three orbital bones (OB: Orbital Bones; NB: Nasal Bone)