Updated: Sep 6, 2019
Courtesy of Almoosa Specialist Hospital
10-years-old male with ventriculoperitoneal shunt
CASE 6 ANSWER
A large simple cyst (yellow arrows) communicates with a dilated 4th ventricle (yellow star), expands the posterior fossa, leads to superior rotation of a hypoplastic vermis (green arrow), anteriorly displaces a flattened brain stem (red arrow), and causes obstructive hydrocephalus (white arrows). Note the presence of a ventriculoperitoneal shunt (black arrow).
The classic form manifests as a posterior fossa cyst communicating with a dilated fourth ventricle and leading to the superior rotation of a hypoplastic vermis, elevation of the torcular herophili, scalloping of the occipital bone.
Hydrocephalus is a typical early manifestation.
Commonly associated with other syndromic and non-syndromic features, such as cortical dysplasia, corpus callosum malformations, and other findings.