COLLOID CYST OF THE THIRD VENTRICLE: REPORT OF TWO
CASESN. EZZAAIRI, M. MAATOUK, M.A. JELLALI, W.MNARI, A. ZRIG, W. HARZALLAH, R.SALEM, M. GOLLI
Service d’imagerie médicale, CHU Fattouma Bourguiba Monastir –TUNISIE
NR 32
Colloid cysts (CC) are relatively rare intracranial benign congenital
tumors accounting for 0.5%–1% of primary brain tumors and 15%–
20% of intraventricular masses.
Colloid cysts are slowly growing non-neoplastic cysts that are
predominantly arising in the anterior region of the 3rd ventricle (more
than 99%).
They are classically presenting during the 3rd to 4th decades.
Introduction
Typically, patients are asymptomatic, although
colloid cysts may cause symptoms by obstructing
the foramen of Monro.
Both magnetic resonance imaging (MRI) and
computed tomography (CT) can be used for the
diagnosis.
Introduction
In this report, we present 2 cases of CC of the
3rd ventricle, along with the findings of
radiological imaging.
Case report
A 57-year-old man, admitted following head injury.
A unenhanced CT scan (NECT) did not demonstrate
any intracranial hemorrhage but there hyperdense
foramen of Monro mass.
Patient one
MRI confirmed the presence of a small colloid cyst at the foramen of Monro which was homogeneously hyperintense to brain on T1 WI (B). T2WI (C) shows a mixed signal mass with a focus of profound hypointensity. FLAIR sequence (D) shows the cyst does not suppress. There was no restriction in DWI (E)
A
B
C
D
E
A 48-year-old man presented to the emergency
department, with a 2 day history of frontal headache
and nausea associated with an episode of vomiting.
He was neurologically intact, with no signs of
meningism.
Patient 2
NECT shows a small, Well-
demarcated round, hyperdense
foramen of Monro mass with
obstructive hydrocephalus.
There was no enhancement
after injection.
MRI imaging shows a colloid cyst at the foramen of Monro (A). The cyst is
hyperintense on T1 WI (B) and is causing moderate hydrocephalus with
transependymal CSF flow (C). T1WI with gadolinium revealed no enhancement (D).
A
B
C
D
Colloid cyst or paraphyseal cyst is the most common tumours in the
3rd ventricle.
It’s wedged into foramen of Monro in over 99% of cases.
Rare reports describe other locations including the leptomeninges,
cerebellum, lateral and 4th ventricles.
CC, like neurenteric and Rathke cysts, is derived from embryonic
endoderm.
Discussion
Age : 3rd to 4th decade
Rare in children
40-50% asymptomatic, discovered incidentally
The most common sign is a headache (50-60%)
Acute foramen of Monro obstruction may lead to rapid
onset hydrocephalus, herniation and death
Discussion
Prognosis is variable:
• 90% of CC are stable
• 10% can expand rapidly, causing coma and death.
• Criteria of poor prognosis are:
• Younger patients
• Larger cyst, hydrocephalus
• Iso/hypodense on NECT, often hyperintense on T2WI
Discussion
CC is a smooth, spherical, well-delineated cysts. The content is composed of a viscous gelatinous material (colloid)
with variable viscosity.
Histologically, CC is characterized by a simple or pseudostratified
epithelial lining with interspersed goblet cells and scattered ciliated
cells.
The cyst contents is PAS positive and composed of.
It may contain necrotic leucocytes and cholesterol clefts.
Pathologic findings
Either CT or MRI may help in diagnosing a CC,
although MRI has a few advantages.
The multiplanar capabilities of MRI optimally
demonstrate the classical location of the cyst, and typical
signal intensities in the cyst help helpful in the early and
correct diagnosis of this entity.
Imaging
On NECT, approximately 2/3 of CC are slightly hyperdense. It may
occasionally be hypodense or isodense.
The density is correlated inversely with hydratation state.
Calcification or hemorrhage are rare.
After administration of iodinated contrast material, no enhancement
of the mass lesion or a thin rim of enhancement may be present.
Imaging : CT
On T1WI, the signal of CC is correlates with cholesterol concentration:
• 2/3 are hyperintense
• 1/3 are isointense
On T2 WI, the signal is more variable:
• the majority are isointense to brain.
• ¼ are mixed “black hole” effect
On FLAIR sequence; the signal cyst is not suppressed
There are not restriction on DWI
Imaging : MRI
The imaging appearance of a colloid cyst is almost
pathognomonic.
The most common “lesion” mistaken for a colloid cyst is
CSF flow artifact (MR pseudocyst) caused by pulsatile
turbulent CSF flow around the foramen of Monro.
Multiplanar technique confirms artifact.
Differential diagnosis
Occasionally, a neurocysticus cyst may occur at the
foramen of Monro. However, multiple lesions within
parenchyma and cisterns are usually shown in
neurocysticercosis.
Neoplasms such as subependymoma or choroid plexus
papilloma that may occur at the foramen of Monro are
much less common and typically enhanced.
Differential diagnosis
Prophylactic surgery for asymptomatic CC of the 3rd ventricle
remains controversial. However, the possibility of spontaneous
rupture of these cysts should also be kept in mind.
The most common treatment consist on complete surgical
resection.
Recurrence is rare, if resection is complete
Treatement
