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| Discussion |
A 58-year- male was referred with complaints of gait imbalance since
25 days and headache with vomiting since 10 days. Neurological examination
revealed bilateral cerebellar signs. No focal neurological deficit could
be elicited.
RADIOLOGICAL Examination:
Plain and contrast enhanced CT scans of the brain were performed. These
showed a mixed attenuation lesion in the left cerebellar hemisphere with
perifocal edema causing compression of the 4th ventricle resulting in obstructive
hydrocephalus. Following contrast injection, intense uniform enhancement
of a pial- based solid component is seen. A cystic, non enhancing component
of the lesion is seen just anterior to the enhancing nodule (Fig 1, 2).
This solid-cystic lesion with such enhancement pattern was though to represent
a cerebellar hemangioblastoma
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Fig.
1
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Fig.
2
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CT angiography shows
a highly vascular mass lesion in the posterior fossa with early draining
veins . The arterial supply was from the left PCA & SCA (Fig 3,4)
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Fig.
3
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Fig.
4
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Serial axial sections from an MR examination show the cystic component of
lesion to be hypointense on T1 weighted scans & hyperintense on T2WI . The
inhomogenously isointense mural nodule is seen on T1WI. This turns hyperintense
on T2WI (Figs 5,6,7,8)
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Fig.
5
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Fig.
6
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Fig.7
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The radiological diagnosis of hemangioblastoma was confirmed on intra-operative findings & on histopathological examination.
DISCUSSION:
The most common true
blood vessel tumors in the brain are hemangioblastomas, which account for
about 7% of all post fossa tumors in adults. These represents capillary
hemangiomas that contain proliferative blood vessel cells or hemangioblasts
and are most often seen in the 3-4th decades with a male predominance. Clinical
presentation is usually with headache, vomiting, confusion, blurred vision,
neck pain & ataxia. Intratumoral hemorrhage can abruptly precipitate symptoms.
Polycythemia may found. Hemangioblastomas are primary characteristics of
Von Hippel Lindau disease. The vermis & cerebellar hemispheres are frequently
affected. They are typically peripheral & close to pial surfaces from which
they obtain their blood supply. Usual morphologic types are solid, solid
with cyst and cyst with a nodule.
Hemangioblastomas are highly vascular & often show prominent vascular pedicles
& draining veins. CT reveals a cystic mass which is isodense with CSF &
containing strongly contrast enhancing peripheral mural nodule in most of
the cases. MR shows the cystic portion to be usually hypointense on T1 &
follow signal changes of CSF. Solid portions appear isointence with adjacent
parenchyma on T1 w images & show increased signal on T2 W scans. Intense
enhancement is seen after contrast administration. Variable peritumoral
edema & mass effect are demonstrated.
The vascular supply of hemangioblastomas may be identified as serpentine
areas of signal void within or near the rim of these tumors on SE images.
Angiography shows dense & prolonged staining of the tumor nidus within an
avascular cyst. Differential diagnosis include cystic ependymoma, cystic
astrocytoma. These have frequent calcification within the large nodules
& they lack angiographic blush of mural nodule. Unusual vascular malformation
and cystic metastases are other differential diagnoses.