DOI:10.2214/AJR.07.7027
AJR 2007; 189:S55-S57
© American Roentgen Ray Society
AJR Teaching File: Intraventricular Mass
Paul Shogan1,
Kevin P. Banks2 and
Stephen Brown2
1 Department of Radiology, Walter Reed Army Medical Center, Bldg. 2 Rm. 1x, 6900
Georgia Ave. NW, Washington, DC 20307.
2 Department of Radiology, Brooke Army Medical Center, MCHE-DR, 3851 Roger
Brooke Dr., Fort Sam Houston, TX 78234.
Received July 2, 2005;
accepted after revision December 27, 2005.
The opinions and assertions contained herein are the private views of the
authors and are not to be construed as official or as reflecting the views of
the Department of the Army or the Department of Defense.
Address correspodence to K. P. Banks
(kevin.banks{at}amedd.army.mil).
Keywords: intraventricular meningioma • meningioma
Clinical History
A 71-year-old woman presents to the emergency department for a syncopal
episode. Unenhanced head CT is performed to screen for any acute intracranial
abnormalities. Subsequent contrast-enhanced MRI is recommended to further
evaluate the abnormal findings.
Radiologic Description
Unenhanced axial CT of the head and brain shows a hyperdense,
well-circumscribed 2-cm mass in the atrium of the right lateral ventricle
(Fig. 1A). Scant rim
calcifications are seen. Only mild adjacent vasogenic edema is seen, and there
are no findings of hydrocephalus. Subsequent contrast-enhanced MRI reveals the
mass to be isointense to gray matter on T1-weighted sequences and hypointense
compared with the cortex on T2-weighted imaging, with mild surrounding edema
present (Figs. 1B and
1C). The lesion avidly enhances
after gadolinium administration (Fig.
1D).
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Fig. 1A —71-year-old woman with syncope. Unenhanced axial CT scan of
brain shows hyperdense, well-circumscribed 2-cm mass in atrium of right
lateral ventricle. Note scant rim calcifications. Only mild adjacent vasogenic
edema is seen, and there are no findings of hydrocephalus.
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Differential Diagnosis
The differential diagnosis in adults with an intraventricular mass is
glioma (astrocytoma, subependymoma, giant cell astrocytoma), meningioma,
ependymoma, choroid plexus papilloma, metastasis, and cysticercosis. In
children, the differential diagnosis is choroid plexus papilloma, ependymoma,
primitive neuroectodermal tumor (PNET), teratoma, and astrocytoma.
Diagnosis
The diagnosis is meningioma.
Commentary
The discovery of an intraventricular mass poses the challenge of correctly
deriving a focused differential diagnosis. In the pediatric population, solid
lesions in the lateral ventricle include choroid plexus papillomas,
ependymomas, PNETs, teratomas, and astrocytomas. In the adult, a
well-circumscribed mass localized to the same region may be a glioma,
ependymoma, meningioma, metastasis, or cysticercosis
[1].
Neoplasms in the lateral ventricles frequently obstruct the ventricles,
producing hydrocephalus and its associated symptoms. Patients may be
asymptomatic or may present with varied symptoms such as contralateral sensory
or motor deficits, homonymous hemianopsia, aphasia, cranial nerve palsies, and
seizures [1,
2].
In adults, atrial intraventricular meningiomas are among the most common
tumors seen in the lateral ventricle. Although rare, accounting for only 0.7%
of all meningiomas, most cases occur in the left lateral ventricle of
middle-aged or older women [1].
The cells of origin are believed to be arachnoid cap cells confined to the
choroid plexus. CT reveals a sharply demarcated lobular mass with
hyperattenuation and periventricular edema. On MRI, the lesion can appear as
iso- to hypointense compared with gray matter on T1-weighted images and iso-
to hypointense on T2-weighted images, with intense enhancement of the mass
[1,
2]. The low signal intensity on
T2-weighted images is one of the key features of meningioma, greatly aiding in
the correct imaging assessment.
Correspondingly, a choroid plexus papilloma may also concentrate to the
atrium of the lateral ventricle in 50% of cases. However, most cases occur in
the pediatric population and represent about 2–4% of pediatric brain
tumors. On CT and MRI studies, the mass may appear similar to an
intraventricular meningioma except for a variable hyperintense signal on
T2-weighted imaging and flow voids
[1].
Subependymomas are also frequently observed in the lateral ventricle. The
incidence is more common in middle-aged to older men. CT shows a well-defined,
lobulated growth with iso- to hypoattenuation, calcification, and occasional
peritumoral edema. MRI of subependymomas shows findings comparable to those
seen on MRI of intraventricular meningiomas. However, variable enhancement is
seen with contrast administration
[1].
Subependymal giant cell astrocytoma, the most common cerebral tumor in
tuberous sclerosis, occurs during the first and second decades of life and
arises in the lateral ventricle. CT illustrates an iso- to slightly
hypoattenuated mass. However, the distinctive feature is a contrast-enhancing
mass near the foramen of Monro. MRI findings are analogous to those of an
intraventricular meningioma
[1].
Astrocytoma is the most commonly found pediatric brain neoplasm, but it has
also been described in young adults
[3]. An astrocytoma usually
affects the cerebellar hemispheres; however, it may involve the foramen of
Monro. On CT, an astrocytoma appears as a cystic or hypodense solid mass. On
MRI, this low-grade tumor often looks indistinguishable from an
intraventricular meningioma
[4].
PNETs may also arise in the lateral ventricles, although they rarely do so.
Often thought of as the second most common pediatric malignancy, PNETs account
for 0.4–1% of all adult CNS neoplasms. In contrast to astrocytoma, the
lesion appears as hyperattenuated on unenhanced CT scans, and evidence of
vasogenic edema may be seen. This neoplasm exhibits similar MRI signal
intensities as a choroid plexus papilloma, but tends to enhance more
vigorously after the administration of contrast material
[3].
Intraventricular ependymomas are also well-circumscribed lesions, occurring
in patients ranging in age from 1 month to 81 years. Unenhanced CT shows
isodense, partially calcified lesions with intense contrast enhancement. MRI
reveals heterogeneous intensity on T1-weighted images and hyperintense signal
on T2-weighted sequences
[1].
The atrium of the lateral ventricle is also a known site for the metastatic
spread of renal cell carcinoma, lung carcinoma, melanoma, gastric carcinoma,
colon carcinoma, and lymphoma. On CT and MRI studies, metastatic disease may
occasionally mimic the signal characteristics of an intraventricular
meningioma [1,
4].
Intraventricular teratomas are heterogeneous masses with regions of low and
high attenuation representing fat and calcification, respectively. On MRI,
T1-weighted images show an irregular lobulated mass with a hypointense signal.
T2-weighted images are often of mixed signal intensity
[4].
Cysticercosis may also manifest as an intraventricular mass. T1-weighted
images confirm intraventricular cysts as hyperintense compared with CSF.
T2-weighted images show similar high signal intensity of both cyst fluid and
CSF, masking proper identification of the cyst. A high-signal-intensity rim on
proton density–weighted images may also be noted. On CT, an enhancing
ring or focal calcification may be evident
[4,
5].
Although imaging studies may suggest the diagnosis of a particular
neoplasm, all of these tumors may present with varied imaging patterns, none
of which is truly pathognomonic.
Objective
The educational objectives of this teaching article are to review the
various entities that may present as an intraventricular mass in children and
adults, and to discuss the clinical and radiologic features by which to
analyze the lesions in order to develop a concise and accurate differential
diagnosis.
Conclusion
The evaluation of an intraventricular mass provides a significant clinical
challenge to radiologists. These entities are infrequently encountered and
have many overlapping imaging features. This case illustrates the classic
features of an intraventricular meningioma, one of the more common tumors to
present in adults.
References
- Koeller KK, Sandberg GD. From the archives of the AFIP. Cerebral
intraventricular neoplasms: radiologic–pathologic correlation.
RadioGraphics 2002;22
:1473
–1505[Abstract/Free Full Text]
- Black PM. Meningiomas. Neurosurgery1993; 32:643
–657[Medline]
- Koeller KK, Rushing EJ. From the archives of the AFIP.
Medulloblastoma: a comprehensive review with radiologic–pathologic
correlation. RadioGraphics 2003;23
:1613
–1637[Abstract/Free Full Text]
- Eisenberg RL. Clinical imaging: an atlas of differential
diagnosis, 4th ed. Philadelphia, PA: Lippincott Williams &
Wilkins, 2002: 433
- Zee CS, Segall HD, Boswell W, Ahmadi J, Nelson M, Colletti P. MRI
of neurocysticercosis. J Comput Assist Tomogr1988; 12:927
–934[Medline]
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Clinical History
Radiologic Description
