NEONATE WITH OCCIPITAL SCALP DEFECT: Correspondence

A full-term neonate was born to an 18-year-old, G1, Native-American female whose antepartum course was notable for crystal methamphetamine use and tobacco smoking. Prenatal ultrasounds showed a posterior fossa cyst, ventriculomegaly and absence of brain tissue in the right hemisphere. At delivery, a scalp defect was present in the right occipital region and focally covered by a thin, tense membrane. Autopsy revealed acalvaria with cranial contents enclosed by hair-bearing skin. The skull base was fully intact. Fixed brain weight was 302 g and a vague gyral pattern was appreciated. The right hemisphere was cystic with an incomplete rim of brain parenchyma. Cerebellum was not grossly identified; the brainstem region appeared replaced by yellow firm tissue in continuity with a normal-appearing spinal cord. The face was normal, and the remaining organs demonstrated no malformations. Microscopy of the right occipital region revealed a thin membrane covering subjacent gliotic brain parenchyma with cerebrovasculosa features. The underlying occipital lobe showed polymicrogyria. The brainstem was partially replaced by mature lipomatous tissue with cranial nerves present. Cerebellar folia and deep nuclei were microscopically identified. Acalvaria is a rare entity with few reported cases. The precise etiology is unclear. This case demonstrates acalvaria associated with prenatal maternal drug use.