Key Takeaways
- A published case from Oran, Algeria reports complete facial duplication (diprosopia) in a male fetus at 24 weeks of gestation, initially misread on outside ultrasound as conjoined (parapagus) twins.
- Management considered maternal risk from a prior uterine scar and maternal distress; a planned caesarean section was chosen for medical termination. The newborn died within minutes.
- Diprosopia is extremely rare and often fatal; a few partial forms have survived according to historical and modern reports.
- Disturbance of Sonic Hedgehog (SHH, Sonic Hedgehog) signaling in early embryogenesis is frequently discussed as a key mechanism in craniofacial duplication.
- Accurate prenatal diagnosis and expert counseling are essential because imaging can mimic conjoined twinning and prognosis is generally poor.
Case From Oran, Algeria
A pregnant patient at 24 weeks with a previous uterine scar was referred after an outside ultrasound suggested conjoined (parapagus) twins. A multidisciplinary team weighed the risk of uterine rupture and maternal distress, opting for medical termination via a planned caesarean section. At delivery, the neonate exhibited total facial duplication (diprosopia) and died within minutes.
Publication timeline of the report: Received 14 December 2024, Accepted 23 December 2024, Published 28 December 2024.
Embryology and Mechanism
Sonic Hedgehog (SHH, Sonic Hedgehog) signaling orchestrates the patterning of the craniofacial region. Experimental and clinical observations associate excess or dysregulated SHH activity with widening or duplication of midline facial structures, while decreased SHH activity is linked to midline deficits (for example, holoprosencephaly). In diprosopia, abnormal SHH pathway activity is a leading mechanistic hypothesis rather than fusion of two embryos.
Diagnostic Pitfalls and Imaging
On routine prenatal ultrasound, diprosopia can be misinterpreted as conjoined twinning (such as parapagus). When facial duplication is suspected, referral to a fetal medicine center for expert morphologic assessment, 3D/4D ultrasound, and/or fetal MRI improves diagnostic accuracy and counseling.
Epidemiology and Prognosis
Diprosopia is exceedingly rare, with estimates in the literature ranging from approximately 2 per 1,000,000 births in some datasets to 1 in 15 million globally. Most complete cases are stillborn or die shortly after birth. A small number of partial duplications have survived beyond the neonatal period, typically with significant associated anomalies.
Clinical Guidance and Counseling
- Differentiate diprosopia from classic conjoined twinning because the mechanisms, prognosis, and counseling differ.
- Engage a multidisciplinary team (maternal–fetal medicine, neonatology, genetics, imaging specialists).
- Integrate maternal risks (for example, prior uterine scar) into planning.
- Provide clear, compassionate counseling about the very poor prognosis of complete duplication and the limited but real reports of partial-survivor outcomes.
- Document imaging and findings rigorously to contribute to the scarce evidence base.
Definitions & Translations
Diprosopia
- Plain definition (English): A congenital malformation with craniofacial duplication—duplication of facial structures on a single head and single trunk.
- Linguistic origin/borrowing status: From Greek di- (“two”) + prosōpon (“face”).
- Scientific acceptance: Recognized in teratology and developmental biology as a rare craniofacial duplication entity.
Parapagus
- Plain definition (English): A conjoined twinning form with two bodies joined side-by-side, often sharing a trunk.
- Linguistic origin/borrowing status: From Greek para (“beside”) + pagos/pagē (“fixed”).
- Scientific acceptance: Standard term in the medical classification of conjoined twins.
Sonic Hedgehog (SHH, Sonic Hedgehog) Signaling
- Plain definition (English): A developmental signaling pathway critical for patterning of the neural tube and facial structures; SHH is the ligand that initiates the cascade.
- Linguistic origin/borrowing status: Named after the Drosophila “hedgehog” gene family; “Sonic” originates from popular culture and is fully adopted in science.
- Scientific acceptance: Universally accepted in developmental biology and medical genetics.
Sources
- Djelti S., Benmoumen M. Y. (2024). Facial Duplication (Rare Diprosopia) About a Case. Journal of Gynecological & Obstetrical Research. Primary case report (PDF). https://oaskpublishers.com/assets/article-pdf/facial-duplication-rare-diprosopia-about-a-case.pdf
Role: The Oran case with dates (received, accepted, published), clinical course, and interpretation. - Rehder H., Kircher S., Schoner K., Smogavec M. (2023). Brain malformations in diprosopia observed in clinical cases, museum specimens and artistic representations. Orphanet Journal of Rare Diseases. Article page. https://ojrd.biomedcentral.com/articles/10.1186/s13023-023-02617-5
Role: Peer-reviewed synthesis of diprosopia brain malformations and definitions. - Rehder H., et al. (2023). Same article — direct PDF. https://link.springer.com/content/pdf/10.1186/s13023-023-02617-5.pdf
Role: Verified PDF access to the Orphanet JRD paper. - Nair N. M., et al. (2021). Preterm infant with diprosopus and holoprosencephaly. Clinical Case Reports. Open-access full text (PMC). https://pmc.ncbi.nlm.nih.gov/articles/PMC8695654/
Role: Case linking facial duplication with severe midline brain anomalies, discussing SHH-related mechanisms. - Trevisani V., et al. (2023). Diprosopus: A Rare Case of Craniofacial Duplication and a Systematic Review of the Literature. Open-access full text (PMC). https://pmc.ncbi.nlm.nih.gov/articles/PMC10530716/
Role: Case + systematic review with phenotypic spectrum and literature context. - Salah F. O., et al. (2024). Partial facial duplication (diprosopus): a case report and literature review. Journal of Medical Case Reports. Article page (open access). https://jmedicalcasereports.biomedcentral.com/articles/10.1186/s13256-024-04423-4
Role: Recent peer-reviewed case illustrating partial forms and counseling. - YouTube — My Friend with Diprosopus (Two Faces), Special Books by Special Kids (SBSK). https://www.youtube.com/watch?v=44z97i-Ek0Q
Role: Verified, current video offering accessible context about living with craniofacial duplication (translated to English in this article where referenced).
Closing Notes
Complete facial duplication is among the rarest craniofacial anomalies. The Oran case illustrates how precise diagnosis, careful risk balancing, and empathetic counseling shape decisions when prognosis is overwhelmingly poor. Early identification and referral to specialist teams help families understand options and prepare for outcomes.
My Diary - Leonardo Cardillo 