Arachnoid cyst of the posterior cranial fossa with dysgenesis of corpus calosum and atretic parietal cephalocele
Diagnosis almost certain
Presentation
Increased head circumference with a parietal swelling at the midline.
Patient Data
Age: 5 months
Gender: Female
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The MRI sequences demonstrate:
- large extra-axial cyst of CSF signal on all sequences, compressing the left cerebellar hemisphere and the 4th ventricle which is displaced to the right with remodeling effect on the adjacent bone in keeping with an arachnoid cyst
- marked dilatation of the 3rd and lateral ventricles (hydrocephalus)
- dysgenesis of the corpus callosum
- small subcutaneous midline parietal mass with no skin cover, adjacent to a calvarial defect in keeping with an atretic parietal cephalocele
Case Discussion
MRI features of arachnoid cyst of the posterior cranial fossa compressing the left cerebellar hemisphere and 4th ventricle with associated hydrocephalus, callosal dysgenesis and atretic parietal cephalocele.