Clínica de Diagnóstico por Imagem – CDPI, Rio de Janeiro - Brazil.
Definition
Holoprosencephaly is a complex abnormality of the forebrain resulted from a failure of cleavage of the prosencephalon. Alobar holoprosencephaly is the most severe form characterized by the fused cerebral hemispheres, single primitive ventricle, fused thalami. The third ventricle, neurohypophysis, and olfactory bulbs are absent. The head is generally small.
Case report
We present a case of alobar holoprosencephaly with proboscis and cyclopia observed at 27 weeks of gestational age.
Figures 1, 2: Figure 1 shows axial ultrasound view of the fetal head with monoventricle and fused thalami. Figure 2 shows the same view obtained by MRI (T2-weighted). Note the proboscis in both figures (arrows).