Ependymal cyst
Ependymal cysts are rare benign neuroepithelial cysts lined by ependymal cells. Most are small and asymptomatic and only cause symptoms if large.
A glioependymal cyst and an ependymal cyst are the same things. They are both terms used to describe a cyst that originates from ependymal cells, which are specialized cells that line the ventricles of the brain and the central canal of the spinal cord. These cysts are typically benign and can occur in various locations within the central nervous system. The terms “glioependymal cyst” and “ependymal cyst” are used interchangeably to refer to this type of cyst.
On the other hand, a neuroglial cyst, also referred to as a glial cyst or an astroglial cyst, is a type of cyst that contains a fluid-filled cavity lined by glial cells, which are supportive cells of the nervous system. Neuroglial cysts can occur in various locations within the brain or spinal cord, and their size and symptoms can vary depending on the specific location and characteristics of the cyst.
While both types of cysts involve glial cells and can occur in the central nervous system, glioependymal cysts specifically involve ependymal cells, whereas neuroglial cysts can involve different types of glial cells such as astrocytes. Therefore, they are distinct entities with some differences in their origin and characteristics.
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
perivascular cyst
neurocysticercosis
porencephalic cyst
if intraventricular consider
intraventricular arachnoid cyst
asymmetrical ventricles
choroid plexus cyst: shows restricted diffusion
subarachnoid space
arachnoid cyst
epidermoid cyst
Noncommunicating interhemispheric cysts, such as interhemispheric arachnoid cyst or ependymal cyst, with callosal agenesis are also in the second category. A careful review of embryologic development is essential for understanding these midline cysts and for making a more accurate radiologic diagnosis 1).