Unique anomalies in cephalothoracopagus Janiceps conjoined twins with implications for multiple mechanisms in the abnormal embryogenesis

Abstract

The anatomic features of female conjoined twins with the Janiceps type of cephalothoracopagus are described. Abnormalities included bilateral clefts of the alveolar arches, shared rudimentary mandible, high, arched clavicles, multiple rib deformities, single shared foregut and small intestine, absent large intestines, omphalocele, multicystic kidneys, hypoplastic lungs, interconnected aortas and neck vessels, single ovary with elongated uterus in each twin, displaced labia, abnormal segmentation of the vertebrae, spinal dysraphism, diastasis of the symphysis pubis, malrotated lower extremity, bilateral posterior dislocation of the hips, and club feet. There were two hearts with internal anomalies. Both spinal cords had a myelocele in the lumbar region. The abnormalities noted in previous reports of conjoined twins of this type are reviewed and compared. We propose that factors associated with conjoining, dysgenetic (developmental) defects, and deformations resulting from crowding in utero all may have been important in the abnormal development in this case.

Janiceps Conjoined Twins with Extreme Asymmetry: Case Report with Complete Autopsy and Histopathologic Findings

“…In the case described by Sperber and Machin [9], there were separate larynges oriented to the vertebral axis, and the lungs and hearts were oriented to the faces. Baron and colleagues [10] reported a complex symmetric case of janiceps twinning with duplication and severe malformations caudally and reviewed 10 previously reported cases of janiceps cephalothoracopagus twins. All cases listed in this review had 2 hearts with variable defects, 4 lungs, some degree of gastrointestinal/hepatopancreatobiliary anomaly ranging from Meckel's diverticulum to intestinal/liver/pancreatic duplications, and duplication of central nervous system (CNS) structures.…”

Heteropagus conjoined twins due to fusion of two embryos: Report and review

“…One proposed mechanism is disorganization due to a low penetrance single gene defect, which would increase the risk of subsequent affected offspring [Petzel and Erickson, 1991]. CT are generally thought to develop from incomplete fission of a single zygote [Baron et al, 1990], although preimplantation embryonic fusion has also been suggested [Thompson et al, 1991]. In fact, mares have been shown to undergo asynchronous ovulations in which the initial implanted embryo acts as an impediment to the movement of the other, resulting in fixation of both embryos in the same uterine location [Ginther, 1992].…”

Conjoined twins: Morphogenesis of the heart and a review

“…It has been suggested that each face in the janiceps type is made up of the right side of one twin and the left side of the other [Guttmacher and Nichols, 1967]. The degree of conjunction and deformity depends on the extent of fusion of the trunks [Wedberg et al, 1979; Delprado and Baird, 1984; Merwin and Wright, 1984; Baron et al, 1990]. The thoracic and abdominal organs are often duplicated.…”