Apparent encephalocele in twin fetus papyraceus with twin-reversal arterial perfusion.

An apparently iniencephalic or exencephalic monoamniotic monochorionic female twin fetus, delivered as a fetus papyraceus at 28 weeks of gestation, had severe anomalies of the central nervous system and spine, including occipital encephalocele with a defect of the occipital bone. The encephalocele contained a spherical mass of autolyzed brain tissue without identifiable cerebellum or vermis. The cervical canal was widely patent dorsally, there were severe bony anomalies, including agenesis and fusion of vertebrae in the cervicothoracic spine. The upper limbs were absent. All organs were hypoplastic and autolyzed. The hypoplastic heart had three chambers. The placenta was monochorionic and monoamniotic; barium injection showed a twin-reversal arterial perfusion and entanglement of the umbilical cords.