Elevated alpha-fetoprotein and coexisting spinal defects in a fetus are characteristic of which anomaly?

Elevated alpha-fetoprotein and coexisting spinal defects in a fetus are characteristic of which anomaly?

• A. Acrania
• B. Arachnoid cyst
• C. Dandy-Walker
• D. Hydranencephaly

Answer: (A)

Elevated alpha-fetoprotein indicates leakage of fetal AFP into the amniotic fluid from defects that expose neural tissue, such as skull or neural tube problems. In acrania, the calvarial bones are absent, leaving brain tissue exposed and not protected by a skull. This exposure leads to markedly higher AFP levels in the amniotic fluid and often accompanies other neural tube closure defects, which can include spinal abnormalities. On ultrasound, you’d see absence of the cranial vault with exposed or underdeveloped brain tissue, sometimes with accompanying spinal defects reflecting broader neural tube issues. The other conditions don’t typically present with both high AFP and spinal defects: an arachnoid cyst is a fluid-filled space within the arachnoid layer and doesn’t involve skull absence or elevated AFP; Dandy-Walker malformation is a posterior fossa anomaly with an enlarged third ventricle and vermian malformation, not linked to high AFP or spinal defects; hydranencephaly shows extensive loss of cerebral hemispheres without the AFP-spinal defect pattern described.

Elevated alpha-fetoprotein indicates leakage of fetal AFP into the amniotic fluid from defects that expose neural tissue, such as skull or neural tube problems. In acrania, the calvarial bones are absent, leaving brain tissue exposed and not protected by a skull. This exposure leads to markedly higher AFP levels in the amniotic fluid and often accompanies other neural tube closure defects, which can include spinal abnormalities. On ultrasound, you’d see absence of the cranial vault with exposed or underdeveloped brain tissue, sometimes with accompanying spinal defects reflecting broader neural tube issues. The other conditions don’t typically present with both high AFP and spinal defects: an arachnoid cyst is a fluid-filled space within the arachnoid layer and doesn’t involve skull absence or elevated AFP; Dandy-Walker malformation is a posterior fossa anomaly with an enlarged third ventricle and vermian malformation, not linked to high AFP or spinal defects; hydranencephaly shows extensive loss of cerebral hemispheres without the AFP-spinal defect pattern described.