ependymal cyst

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Ependymal cysts are rare benign neuroepithelial cysts lined by ependymal cells. Most are small and asymptomatic and only cause symptoms if large.

On imaging, these cysts are essentially indistinguishable from other intraventricular simple cysts (e.g. intraventricular arachnoid cysts).

Epidemiology

They typically present in young adults. There may be a slight male predilection. Patients are often in their 30s at the time of presentation.

Pathology

It is thought to arise from sequestration of developing neuroectoderm during embryogenesis. They are thin-walled and contain clear serous fluid secreted by the lining ependyma . They are most commonly located deep in the parenchyma, although intraventricular, periventricular and subarachnoid space cysts have also been reported . Ependymal cysts have been postulated to be the entity responsible for the interhemispheric cysts with the Dandy-Walker malformations and agenesis of the corpus callosum.

Markers

GFAP and S100 markers are often positive due to its neuroepithelial lining.

Radiographic features

On imaging, they are well-defined, thin-walled and do not contrast enhance.

CT

Typically periventricular in location. The cyst is isoattenuating to CSF.

MRI

Follows CSF signal on all sequences and does not demonstrate diffusion restriction. Occasionally the cyst may be hyperintense to CSF if there is a high protein content. No contrast enhancement.

Treatment and prognosis

Asymptomatic cysts may be monitored. In surgically resected cases recurrence is extremely rare and the prognosis is excellent.

Large cysts in vulnerable locations may cause obstructive hydrocephalus

Differential diagnosis

if parenchymal consider
if intraventricular consider
- intraventricular arachnoid cyst
- asymmetrical ventricles
- choroid plexus cyst: shows restricted diffusion
subarachnoid space
- arachnoid cyst
- epidermoid cyst