Glial cysts, choroidal cleft cysts, hippocampal sulcus residual cysts, these are often seen, are you diagnosed correctly?

Glial cysts

overview

image

CT

MR

Primary differential diagnosis

Diagnostic compendium

(left) axial plot showing a classic glial cyst
.
This well-demarcated, single-chamber lesion contains clear fluid and does not communicate
with the ventricles.
Peripheral brain tissue is normal
.
Glial cysts are lined with glial cells, astrocytes, and rarely ependymal cells
.

(Right) In a pediatric patient, axial FLAIR images show an incidentally discovered benign looking cyst located in the left frontal subcortical white matter
.
The cyst signals the same as the cerebrospinal fluid in all sequences, without reinforcement
.

(left) Young patient presenting with headache, axial FLAIR image of a cyst showing a cerebrospinal fluid-like signal on the right frontal
.
(Right) In the same patient, axial DWI image shows that the lesion is not diffuse and restricted
.
The fluid in the cyst is emptied and biopsied
.
Histologic examination shows evidence
that the cyst is lined with glial tissue without epithelial components.

Cleft choroidal cyst

overview

image

Key points for optimal imaging: cystic foci resembling cerebrospinal fluid involving the medial temporal lobe, choroidal fissure, and well-demarcated round or oval cysts

NECT: low-density foci on the medial side of the temporal lobe; Can have a mass effect on the hippocampus

MRI: the signal is similar to cerebrospinal fluid in all sequences

The MR sagittal site is typically "spindle" shaped

Coronal T2WI imaging may show a relationship with choroidal fissure

Primary differential diagnosis

pathology

Clinical points

(Left) T1WI shows a large choroidal cleft cyst that produces a mass effect
on the adjacent hippocampus.
These are more incidental findings, with individual cases associated
with complex partial epilepsy.

(Right) In the same patient, axial FLAIR imaging shows a hypochoroidal cyst located just posterior to the hook gyrus
.
The cyst displaces the temporal angle and twists
the normal hippocampus.
In all MRI scan sequences, the cyst signals the same as cerebrospinal fluid

(Left) Coronal T2WI imaging shows a choroidal cleft cyst that shifts the temporal angle, flattening and distorting
the hippocampus and parahippocampal gyrus.

(Right) In a young patient with headache, axial FLAIR stumbles upon a cleft choroidal
cyst located medial to the temporal horn.
These benign cysts are identical to CSF signals in all MR scan sequences, including DWI, without reinforcement
.
These cysts usually do not require treatment unless they are accompanied by drug-refractory epilepsy
.

Hippocampal sulcus residual cyst

overview

image

A string of cysts along the lateral edge of the hippocampus

In all magnetic resonance sequences, the cyst signal is consistent with the cerebrospinal fluid

Primary differential diagnosis

pathology

Represents part of the unfused hippocampal gully

embryology

Clinical points

(left) Normal temporal lobe axial plot shows a string of small cysts on the outside of the hippocampus, a residual cavity distributed along the original hippocampal sulcus, suggesting a residual cyst of the hippocampal sulcus
.
These incidental findings are characteristic
.

(Right) Coronal T1WI image shows a small low-signal cyst on the lateral hippocampus, which signals the same
as cerebrospinal fluid in all scan sequences.
These normal variants are associated with the partial non-fusion of the hippocampal sulcus and do not require treatment
.

(Left) axial T2WI shows small high-intensity cysts
in the hippocampus.
These embryonic hippocampal sulcus unfused residual cavities appear as cerebrospinal fluid-like cysts, and coastal horses are "beaded"
.

(Right) In the same patient, axial FLAIR images show complete inhibition
of residual cyst signals in the hippocampal sulcus.
The "beaded" appearance is typical of these normal variations
.
Enlargement
of the cyst may be seen in patients with temporal lobe atrophy.

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