Discordant congenital malformations in monozygous twins: the amniotic band disruption complex

A stillborn monozygous twin delivered after 26 weeks gestation manifested multiple severe anomalies in association with an aberrant band of amniotic membrane which attached to the fetus' head (exencephaly) and abdomen (gastroschisis), entangled his lower extremities (flexion contractures, atrophy and amputation of digitis) and fixed his body in a position of lateral flexion. He also had bilateral proptosis, lateral facial cleft, absence of the right kidney, and an imperforate anus. The other twin expired after 36 hours but autopsy disclosed no malformations. Discordancy in monozygous twins due to congenital malformations is well known, but has been noted only rarely in association with the amniotic band disruption complex (ABDC). comparison with previous reports shows that in all cases only one member of the twinship was affected. Furthermore, isolated limb lesions (constriction rings and amputations), which are more common manifestations of ABDC than severe eviscerations or craniofacial deformities, have not been reported in twins. These observations support the concept that the severe form of ABDC is an acquired intrauterine lesion and they suggest that isolated limb lesions may not be part of the same malformation complex.