A new phenotype of amniotic band syndrome with occipital encephalocele-like morphology: a case report.

Amniotic band syndrome (ABS) is a congenital abnormality that can cause a variety of deformities. Here, we report a case of ABS in which the amniotic band adhered to the skull, causing a partial cranial defect that was difficult to differentiate from an occipital encephalocele. The mother was a 24-year-old with an unremarkable medical and family history. Ultrasonography performed at 16 weeks showed that the fetus had a membranous structure in the occipital region. Occipital encephalocele was suspected, and she underwent cesarean section at 38 weeks. A male newborn was delivered, and his left occipital skin had a defect measuring 2 cm, from which a cystic structure had prolapsed. Cranial magnetic resonance imaging showed that the cystic structure had homogeneous high signal intensity on T2-weighted images. The neonate then underwent repair of the occipital encephalocele. During the operation, the membranous structures and dura were not continuous. Histological examination revealed that the membranous structures were composed of amnion, suggesting that this was a case of ABS. ABS may present with an encephalocele-like morphology without affecting the brain tissue and meninges. If an atypical encephalocele is found after birth, examination of the placenta may be helpful for a definitive diagnosis.