Diprosopus: a review of the aetiology and case report of early surgery in a 7-week-old infant with partial facial duplication

Preterm infant with diprosopus and holoprosencephaly

“… 2 It is rare for children with complete diprosopus to survive more than a few hours, but for those with incomplete diprosopus who are able to survive, surgical intervention is often needed for functional and esthetic purposes. 6 While it is difficult to place this reported case in the context of other cases of diprosopus due to the rarity and heterogeneity of cases, our case is congruent with the literature in that the affected infant was female, she had duplication and malformation of upper airway features, and she had associated systemic congenital anomalies. The tubular upper airway structures, ectopic scalp tissue, and live birth despite extent and severity of anomalies are unique.…”

“…The exact etiology and pathophysiology of diprosopus remain unknown, although it is likely that they are multifactorial. 6 The traditional model of monozygotic twinning involves the product of a single ovum and sperm that divides to form two embryos, while alternative models suggest that embryonic fusion events underlie this process. 10 Several proposed pathogenic mechanisms for diprosopus exist, including 1) early ventrolateral fusion of two monozygotic embryonic disks with reorganization of merged tissues leading to secondary aplasia and divergence of tissues from the midline; 2) neurocristopathy with fission in a monozygotic gestation that produces two notochords that then generate a duplicated cephalic neural plate, an extra medial cranial neural crest, and alterations in the paraxial mesoderm; and 3) two early primitive nodes in a single embryo prior to the formation of the notochord.…”

“…Stillbirths occur in 50% of all conjoined twins, and the majority of infants born alive do not survive long‐term. 4 , 6 Diagnosis can be made on prenatal ultrasound imaging, and prognosis is variable based on the presence or absence of associated clinical features. Complete facial duplication, which involves the duplication of at least two full facial organs or two structures from two different organs in an individual with one head and one trunk, is commonly associated with other congenital anomalies including the central nervous system, the cardiovascular system, the gastrointestinal system, and the respiratory system.…”

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

“…The etiology and pathogenesis of diprosopus, like others of conjoined twins, remain unknown and are likely to have multifactorial origin (Rabe et al, 2019). Some hypotheses state that the disruption of cell signaling pathways, such as the transforming growth factor‐β (TGF‐β), Sonic Hedgehog (SHH), and Wingless‐type (Wnt), could cause duplication of the head or face (Sadler, 2012).…”

Diprosopus tetraophthalmos: a rare congenital anomaly

“…Stillbirths occur in 50% of all conjoined twins and the majority of infants who are born alive do not survive long term. 4,5 If diagnosis is made early in pregnancy, termination of pregnancy is sometimes considered as an option. 6…”