Diprosopus: Systematic review and report of two cases

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

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.

Prenatal diagnosis of the rarest conjoint twin "diprosopus tetrophthalmus" during anomaly scan: A case report

Twin pregnancy is considered high-risk pregnancy because of its various effects on maternal and fetal physiology. Twin pregnancy can be dizygotic or monozygotic, the latter being less common. Depending upon the period of separation of an embryo, monozygotic twins can share amniotic cavity and placenta with the monochorionic monoamniotic form being the least common type. Diprosopus tetrophthalmus is the rarest form of monozygotic monochorionic and monoamniotic conjoint twin, where there are 2 faces on 1 head with various degrees of duplication of facial and cranial structure. The exact etiology of diprosopus is still unknown however; there are many local environmental and oxidative theories for this anomaly. The incidence of diprosopus is 1 in 180,000 to 15 million births. Here we present a case of 20-year-old female who came for routine anomaly scan of her pregnancy in our hospital which showed the presence of diprosopus tetrophthalmus. Couples agreed to terminate pregnancy after proper counseling from treating physician. Ultrasonography images of anomaly scans as well as post-abortion images of the fetus are discussed in this case report.

Human diprosopus: Case report of a rare congenital abnormality

Diprosopus is a congenital anomaly in which partial or complete duplication of craniofacial structures occurs. Because it is rare, the mortality rate is high, and information concerning this anomaly is scarce. This study describes a case of human diprosopus in a 9-year-old male individual, who has severe complications associated with the central nervous, cardiovascular, respiratory, and digestive systems. Since birth, he has been monitored in a specialized hospital environment, where he has undergone several surgeries and multidisciplinary treatments. Regarding the craniofacial aspects, he had agenesis of the corpus callosum, floor of the nasal cavity, and floor of the anterior cranial fossa, in addition to the presence of bone dysplasia, ocular hypertelorism and cleft palate with nasal and oral teratoma. Regarding dental characteristics, the patient has duplication of the maxilla, mandible, tongue, and some teeth. After complementary imaging exams, several supernumerary teeth were found, with some being impacted and in complex regions, with an indication for extraction due to the risks of impaction, irruptive deviation, root resorption, and associated cystic or tumoral lesions. Because of the numerous complications, knowledge, and preparation of the entire team is necessary for the correct management of the case.

Partial facial duplication (diprosopus): a case report and review of the literature

BACKGROUND

Diprosopus, or craniofacial duplication, is a rare entity that occurs in approximately 1 in 180,000 to 15 million live births. The degree of duplication varies from complete facial duplication to small facial structure duplication like the nose and eye. The cause of diprosopus is unknown though there are proposed factors.

CASE PRESENTATION

Our African patient was a term 72 hours old female neonate who was referred to our center with impression of lower facial duplication with two oral cavity that are located side to side separated by large soft tissue, she also had flat nasal bridge with widely separated nostrils and widely spaced eyes. Besides the facial malformation she had multiple episodes of vomiting with aspiration. Her blood tests were normal. Precontract brain computed tomography (CT) scan confirmed partially duplicated mandible and maxilla, two oral cavity separated by large fatty tissue, brain tissue were well formed and the only abnormality was corpus callosum agenesis and interhemispheric lipoma. In her stay at hospital nasogastric tube (NG) tube feed was initiated and started with antibiotics for aspiration pneumonia. After 25th day the neonatal passed away with possible cause of death being respiratory failure.

CONCLUSION

Craniofacial duplication is a very rare anomaly with only a few cases reported. Most of these patients are stillborn, even if they survive the prognosis is often poor. Early prenatal diagnosis is very important as termination of pregnancy can sometimes be considered an option.

Symmetrical parapagus diprosopus: A comparative, computed tomographic, and pathoanatomical study of a new case in domestic pig

BACKGROUND

Parapagus diprosopus are conjoined twins characterized by craniofacial duplication and only one body, representing one of the rarest types of these twins. Their occurrence has been recorded in different species of vertebrates, including humans, but few cases have been studied in domestic pigs.

CASE

A pair of conjoined twin pigs was studied using x-rays, computed tomography, and necropsy. The abnormalities found were compared with those of the rare swine cases presented in the literature as well as with other species, and the different etiopathogenetic possibilities were addressed. The degree of duplication of the head bones decreased caudally, as did that of the structures of the central nervous system. In the two oral cavities, there was a complete cleft palate. All the cervical vertebrae and thoracic vertebrae up to T3 were partially duplicated. The heart and great vessels were normal, as were the other thoracic and abdominal organs.

CONCLUSIONS

The conjoined twin pigs of this study are a case of parapagus diprosopus tetraophthalmus triotus, presenting the same pattern of abnormalities of human diprosopus and that of other species. The scarcity of detailed studies on craniofacial duplication in pigs and the lack of a definitive explanation on the etiology and pathogenesis of conjoined twins shows the need for further research and the publication of more cases.

Phenotypically Discordant Anomalies in Conjoined Twins: Quirks of Nature Governed by Molecular Pathways?

A multitude of additional anomalies can be observed in virtually all types of symmetrical conjoined twins. These concomitant defects can be divided into different dysmorphological patterns. Some of these patterns reveal their etiological origin through their topographical location. The so-called shared anomalies are traceable to embryological adjustments and directly linked to the conjoined-twinning mechanism itself, inherently located within the boundaries of the coalescence area. In contrast, discordant patterns are anomalies present in only one of the twin members, intrinsically distant from the area of union. These dysmorphological entities are much more difficult to place in a developmental perspective, as it is presumed that conjoined twins share identical intra-uterine environments and intra-embryonic molecular and genetic footprints. However, their existence testifies that certain developmental fields and their respective developmental pathways take different routes in members of conjoined twins. This observation remains a poorly understood phenomenon. This article describes 69 cases of external discordant patterns within different types of otherwise symmetrical mono-umbilical conjoined twins and places them in a developmental perspective and a molecular framework. Gaining insights into the phenotypes and underlying (biochemical) mechanisms could potentially pave the way and generate novel etiological visions in the formation of conjoined twins itself.

Diprosopus: A Rare Case of Craniofacial Duplication and a Systematic Review of the Literature

In 1990, Gorlin et al. described four types of craniofacial duplications: (1) single mouth with duplication of the maxillary arch; (2) supernumerary mouth laterally placed with rudimentary segments; (3) single mouth with replication of the mandibular segments; and (4) true facial duplication, namely diprosopus. We describe a newborn born with wide-spaced eyes, a very broad nose, and two separate mouths. Workup revealed the absence of the corpus callosum and the presence of a brain midline lipoma, wide sutures, and a Chiari I malformation with cerebellar herniation. We conducted a systematic review of the literature and compared all the cases described as diprosopus. In 96% of these, the central nervous system is affected, with anencephaly being the most commonly associated abnormality. Other associated anomalies include cardiac malformations (86%), cleft palate (63%), diaphragmatic hernia (13%), and disorder of sex development (DSD) (13%). Although the facial features are those that first strike the eye, the almost obligate presence of cerebral malformations suggests a disruptive event in the cephalic pole of the forming embryo. No major monogenic contribution has been recognized today for this type of malformation.

Symmetrical parapagus diprosopus tetrophthalmos in a bovine calf, with computed tomography imaging, and review of craniofacial duplications

Diprosopia, a congenital defect process also known as craniofacial duplication, is well-recognized in humans and has also been reported in numerous animal species. Here we describe a case of diprosopia in a live mixed-breed beef calf. We used computed tomography imaging to characterize internal and external abnormalities which, to our knowledge, have not been reported in any diprosopic veterinary species. Additional diagnostic tools included postmortem examination and histopathology. This case highlights distinct anatomic features associated with diprosopia and underscores the unique challenges associated with classifying and managing fetal malformations.

Brain malformations in diprosopia observed in clinical cases, museum specimens and artistic representations

BACKGROUND

Diprosopus is a rare malformation of still unclear aetiology. It describes a laterally double faced monocephalic and single-trunk individual and has to be distinguished from the variant Janus type diprosopus.

RESULTS

We examined seven double-faced foetuses, five showing true diprosopus, and one each presenting as monocephalic Janiceps and parasitic conjoined twins. Four of the foetuses presented with (cranio)rachischisis, and two had secondary hydrocephaly. Three foetuses showed cerebral duplication with concordant holoprosencephaly, Dandy-Walker cyst and/or intracranial anterior encephalocele. In the Janiceps twins, cerebral duplication was accompanied by cerebral di-symmetry. In the parasitic twins the cyclopic facial aspects were suggestive of concordant holoprosencephaly. In one of the true diprosopus cases, pregnancy was achieved after intracytoplasmic sperm injection. Whole-exome sequencing, perfomed in one case, did not reveal any possible causative variants.The comparison of our double-faced foetuses to corresponding artistic representations from the Tlatilco culture allowed retrospective assignment of hairstyles to brain malformations.

CONCLUSION

Brain malformations in patients with diprosopus may not be regarded as an independent event but rather as a sequel closely related to the duplication of the notochord and neural plate and as a consequence of the cerebral and associated craniospinal structural instabilities.

A rare case of partial skull and brain duplication in a hatchling Alligator mississippiensis

Errors in development occur in all vertebrates. When severe, these anomalies are lethal and frequently escape attention. In rare cases, animals with profound malformations are born and can provide a glimpse into structures and their respective function that would otherwise go unnoticed. A rare abnormality in a hatchling Alligator mississippiensis is described in which duplication of the skull, face, and brain was incomplete. The rostral skull, face, and associated forebrain, including the olfactory apparatus, were duplicated. However, the caudal skull and brainstem were not. These observations were made with advanced imaging using both computed tomography and magnetic resonance coupled with gross brain dissections. These abnormal features emphasize the complex and intertwined relationship between the development of the brain, face, and skull which are influenced by certain signaling molecules, possible gene mutation(s), and potential environmental factors.

Preterm infant with diprosopus and holoprosencephaly

Diprosopus is an extremely rare congenital anomaly involving craniofacial duplication. The etiology and pathophysiology remain unknown, and no genetic mutations have been definitively associated with the condition. This case describes an infant born at 27-weeks completed gestation with multiple congenital anomalies including diprosopus and discusses the implications of prenatal diagnosis.

Caudal duplication syndrome: a literature review and reappraisal of its pathoembryogenesis

INTRODUCTION

The term caudal duplication syndrome (CDS) was first introduced for complex anomalies of the distal caudal end of the trunk. The pathoembryogenesis of CDS is yet unknown, although a few theories have been proposed. We reviewed the previously proposed pathoembryogenetic theories and suggested a new perspective through the common clinical characteristics shown in CDS cases reported in the literature.

METHODS

We conducted a systematic literature search of the online database PubMed from October 1993 to October 2020, using the search term "caudal duplication syndrome", according to the first mention of this entity. A total of 17 articles with 23 patients were reviewed.

RESULTS

The most common manifestations were the duplication of the distal colon, genitourinary organs, and lower spine. Specifically, the duplicated bladders or uteri contacted their counterpart through a septum, and the duplicated bowels ran parallel. More caudal structures, such as the urethra or anus, were formed separately. The duplication seems to be a result of division by an intervening septum or structure in each part. In addition, duplication was not limited to the structures formed from the caudal cell mass (CCM), such as the distal spine and spinal cord, but also included hindgut structures. Moreover, anomalies involving caudal mesenchymal defects were also present. Considering clinical manifestations that are related to all three germ layers and seemingly the overseptation of these germ layers in CDS patients, with supporting data from animal experiments, events such as late-stage errors involving Hensen's node/the primitive streak and the duplication of the CCM with the hyperplasia of the abnormally located central caudal mesenchyme are probable pathoembryogenetic mechanisms for CDS. The "leakage" of the normal growth power of the caudal mesenchyme into the intervening midline space between the two CCMs and consequent weak lateral and caudal pushes of the caudal mesenchyme may explain the association of caudal agenesis or its related anomalies with CDS.

CONCLUSION

We propose a theory that by a molecular interaction, an insult causes late gastrulation phase problems, resulting in ectopic primitive streak formation, and therefore, a duplication of the CCM is induced. Subsequently, the overactivity of abnormally positioned midline mesenchyme between the two CCMs may divide the hindgut derivatives by a central septum. Underactive lateral and caudal pushes of the caudal mesenchyme may lead to an association of features shown in caudal agenesis.

Characterizing the coalescence area of conjoined twins to elucidate congenital disorders in singletons

Shared anomalies, always located close to the area of coalescence and observable in virtually every type of conjoined twinning, are currently seen as separate anomalies caused by mostly unknown and seemingly unrelated pathways rather than being connected to the twinning mechanism itself. Therefore, most (case) reports about conjoined twins are mere descriptions of (external) dysmorphologies lacking reflections on the possible origin of their concomitant anomalies. As we will demonstrate in this article, shared anomalies are influenced, and in some cases solely and sequentially explained, by interaction aplasia and neo‐axial orientation; two embryological mechanisms to which each set of conjoined twins is subjected and are responsible for their ultimate phenotypical fate. In this review, we consider how the ventral, lateral and caudal conjunction types and their intermediates determine the phenotypic presentation of the twins, including patterns of shared malformations and anomalies, which in themselves can be indistinguishable from those encountered in singleton cases. Hence, it can be hypothesized that certain anomalies in singletons originate in a fashion similar to that in conjoined twins.

A case of diprosopus: a rare form of twinning radiology-pathology correlation

Objectives

Diprosopus is a rare subtype of conjoined twinning, with approximately 30 reported cases in English literature. Due to the rarity of conjoined twins, the mechanism leading to this developmental anomaly is not yet understood.

Case presentation

We present a case of diprosopus with multimodality imaging (prenatal and postnatal), and with pathological correlations. Developmental anomalies include partial duplication of frontal lobes, formation of a midline “third” frontal lobe, as well as orofacial and cardiac anomalies. The constellation of anomalies coincide with development during embryonic days 23–26, where the anterior prosencephalon, prechordal plate/oropharyngeal membrane, and cardiogenic plate are in very close proximity to each other.

Conclusions

This case offers an opportunity to better appreciate the radiologic and pathologic manifestations of diprosopus, and adds to the current body of evidence.

Birth defects surveillance: experiences in Argentina and Colombia

Birth defects (BDs) are structural or functional anomalies, sporadic or hereditary, of prenatal origin. Public health surveillance is defined as the ongoing systematic collection, analysis, and interpretation of outcome-specific data for use in the planning, implementation, and evaluation of public health practice. BD surveillance systems may have different characteristics according to design, coverage, type of surveillance, case ascertainment, case definition, BD description, maximum age of diagnosis, pregnancy outcomes, coding systems, and the location of the coding process (central or local). The aim of this article is to describe and compare methodology, applications, and results of birth defect surveillance systems in two South-American countries: Colombia and Argentina. In both countries, the surveillance systems developed activities in relation to the Zika virus emergency. For most BDs, a statistically significant higher prevalence is observed in Argentina-RENAC than in Colombian registries. This may be due to methodological reasons or real differences in prevalence. The strengths, weaknesses, and the future perspectives of the Argentine and Colombian systems are presented. When developing a surveillance system, the objectives, the available resources, and previous experiences in similar contexts must be taken into account. In that sense, the experience of Argentina and Colombia can be useful for others when developing a birth defect surveillance system.

Two is a Crowd: Two is a Crowd: On the Enigmatic Etiopathogenesis of Conjoined Twinning

In this article, we provide a comprehensive overview of multiple facets in the puzzling genesis of symmetrical conjoined twins. The etiopathogenesis of conjoined twins remains matter for ongoing debate and is currently cited-in virtually every paper on conjoined twins-as partial fission or secondary fusion. Both theories could potentially be extrapolated from embryological adjustments exclusively seen in conjoined twins. Adoption of these, seemingly factual, theoretical proposals has (unconsciously) resulted in crystallized patterns of verbal and graphic representations concerning the enigmatic genesis of conjoined twins. Critical evaluation on their plausibility and solidity remains however largely absent. As it appears, both the fission and fusion theories cannot be applied to the full range of conjunction possibilities and thus remain matter for persistent inconclusiveness. We propose that initial duplication of axially located morphogenetic potent primordia could be the initiating factor in the genesis of ventrally, laterally, and caudally conjoined twins. The mutual position of two primordia results in neo-axial orientation and/or interaction aplasia. Both these embryological adjustments result in conjunction patterns that may seemingly appear as being caused by fission or fusion. However, as we will substantiate, neither fission nor fusion are the cause of most conjoined twinning types; rather what is interpreted as fission or fusion is actually the result of the twinning process itself. Furthermore, we will discuss the currently held views on the origin of conjoined twins and its commonly assumed etiological correlation with monozygotic twinning. Finally, considerations are presented which indicate that the dorsal conjunction group is etiologically and pathogenetically different from other symmetric conjoined twins. This leads us to propose that dorsally united twins could actually be caused by secondary fusion of two initially separate monozygotic twins. An additional reason for the ongoing etiopathogenetic debate on the genesis of conjoined twins is because different types of conjoined twins are classically placed in one overarching receptacle, which has hindered the quest for answers. Clin. Anat. 32:722-741, 2019. © 2019 Wiley Periodicals, Inc.

A Case of Diprosopus Tetraophthalmos: Ocular Findings and Surgical Treatment of Exposure Keratopathy

Diprosopus is a rare variation of conjoined twinning. In this report, ophthalmic findings in an infant with diprosopus tetraophthalmos are presented. A male infant who was born at 33 weeks of gestation to a nonconsanguineous 42-year-old mother and 47-year-old father was examined for orbital abnormalities. The infant had a large head, 2 faces, and 4 eyes, of which 2 were placed laterally and 2 were fused in the midline. In the laterally placed eyes, the pupils were unresponsive to light, and the optic discs were hypoplastic. In the fused eyes, the lower and upper eyelids were also fused, horizontally wide, vertically short, and immobile, resulting in a progressive exposure keratopathy. On the 33rd day of life, a modified total tarsorrhaphy was performed with the use of inhalational mask anesthesia. The patient died due to pneumonia and septicemia on the 45th day of life.