Brain Pathology Case of the Month - April 2008

Contributed by 1Brian H. Le, MD, 2Lauren L. Anthony, MD, 1M. Beatriz S. Lopes, MD
1Department of Pathology-Neuropathology, University of Virginia, Charlottesville, VA
2Department of Pathology, Bronson Methodist Hospital, Kalamazoo, MI


A female neonate was delivered at 38 weeks gestation to an 18 year-old, gravida 1, Native-American female whose antepartum course was notable for crystal methamphetamine and tobacco use early in pregnancy. Prenatal care had been initiated at 11 weeks of gestation, and an ultrasound performed at approximately 20 weeks revealed findings interpreted as a large posterior fossa cyst with mass effect. The cerebellum had not been well visualized, although the impression was that some cerebellar tissue was present. These features were overall felt to reflect a Dandy-Walker cyst. Additional ultrasonographic impressions included a probable porencephalic cyst on the right side, ventriculomegaly, possible agenesis of the corpus callosum, and overall significant absence of brain parenchyma in the right hemisphere. Serial follow-up ultrasound evaluations were performed at approximate 4 week intervals, demonstrating essentially the same intracranial ultrasonographic findings. Of note was that other organs showed appropriate growth progression. At delivery by Caesarian section, the posterior aspect of the neonate's scalp was noted to be covered by a thin, tense membrane, which ruptured during the procedure. Apgar scores were 7 and 9 at 1 minute and 5 minutes, respectively, and death occurred within hours of birth.


At autopsy the face was normally formed. There was an absence of the skull, and cranial contents were enclosed by hair-bearing skin (Figure 1). Within the right occipital region a scalp defect was present, characterized by a thin transparent membrane with focal rupture (Figure 2). The skull base was fully intact.

The brain weighed 302 grams, and after fixation a vague gyral pattern was seen from a superior view (Figure 3). The right hemisphere was predominantly cystic with an incomplete rim of brain parenchyma present. The cerebellum was not grossly identified, and the brain stem region showed partial replacement by yellow-tan, firm tissue in continuity with a normal-appearing spinal cord (Figure 4, arrow).

Microscopic examination of the right occipital region in the area of scalp defect revealed a thin membrane covering subjacent gliotic brain parenchyma and fibrovascular structures similar to cerebrovasculosa (Figure 5). The underlying occipital brain tissue showed features consistent with polymicrogyria (Figure 6) with relative preservation of neuronal lamination in focal areas (Figure 7). Sections of the regions corresponding to the brain stem demonstrated replacement by infiltrating mature lipomatous tissue in association with cranial nerves (Figure 8). However, residual brainstem nuclei, and cerebellar folia and deep nuclei were microscopically identified.

The general autopsy examination of the remainder of the body showed essentially all normal findings, with no additional malformations corresponding to a specific syndrome.


International Society of Neuropathology