Clinical History
66-year-old female patient who attended the emergency room with headache, vomiting and hypertension.
Imaging Findings
CT: Intraventricular mass located in the left atrium, lobulated contour and heterogeneous density, which shows calcifications within and digitiform perilesional oedema.
MRI: Intraventricular mass located in left atrium digitiform perilesional oedema, which has a modest effect on the midbrain compression without shift of midline structures. The lesion shows heterogeneous signal intensity in different sequences, moderate restriction of water diffusion and intense enhancement after contrast administration. Perfusion and spectroscopy shows hypervascular behaviour with high levels of acetylcholine and low levels of creatine and N-acetyl-aspartate.
Arteriography: left trigone mass irrigated by the anterior choroidal artery and both posterior choroidal, located above and lateral to the vein of Galen and the straight sinus.
Discussion
Intraventricular meningiomas are rare, constituting only 0.7% of all meningiomas [1]. Still, this tumour is one of the more common intraventricular neoplasms in the adult population, and in some reports, a meningioma is the most common atrial mass to manifest in an adult patient [2– 5]. Most intraventricular meningiomas occur in patients older than 30 years, with the peak age being between 30 and 60 years (mean, 42 years) [2, 5]. Females are more likely to be affected by a 2:1 ratio [2].
Patients with intraventricular meningiomas present with symptoms related to increased intracranial pressure (headache, nausea, vomiting), contralateral sensory or motor deficits, and homonymous hemianopsia [5].
Intraventricular meningiomas are believed to arise from the arachnoidal cap cells trapped
within the choroid plexus, the tela choroidea, or the velum interpositum. [1, 2]. The trigone of the lateral ventricle is the most common site, with a slight majority of the reported cases being located on the left side [1, 2].Nearly all of these tumours have benign histologic characteristics. However, meningiomas that arise within the ventricles of children have an increased predilection for sarcomatous changes [5]. Metastasis from an intraventricular location is rare [4, 5].
On CT images, intraventricular meningiomas manifest with an appearance similar to that of other intracranial meningiomas: a well-defined globular mass that demonstrates hyperattenuation compared with the brain parenchyma [5]. Local or diffuse ventricular dilatation is present, depending on the degree of obstruction of CSF egress through the ventricular system. Calcification is common (50% of cases), and periventricular oedema, presumably from reversal of transependymal CSF flow, may also be seen [2, 4, 5]. In rare cases, subarachnoid haemorrhage or intraventricular haemorrhage may be seen [2]. As is typical for most intracranial meningiomas, those originating within the ventricles characteristically are isointense to hypointense compared with gray matter with short TR pulse sequences and isointense to hyperintense with long TR pulse sequences [5]. Cystlike regions, secondary to either cystic degeneration or necrosis, may occasionally be noted. Intense but heterogeneous enhancement is almost always seen [5]. MR spectroscopy of intraventricular meningiomas has revealed a pattern similar to that of meningiomas outside the ventricular system, with decreased amounts of N-acetylaspartate and creatine; increased amounts of choline; and variable amounts of lactate, lipids, and alanine [5].
As with other intracranial meningiomas, preoperative embolisation may be efficacious in limiting blood loss and may even produce a reduction in size of the mass before surgery [5].
Differential Diagnosis List
Intraventricular meningioma
Choroid plexus papiloma
Choroid plexus carcinoma
Choroid plexus metastasis
Final Diagnosis
Intraventricular meningioma
