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|Year : 2019 | Volume
| Issue : 3 | Page : 932-933
A rare case of a giant tentorial bicompartmental cystic schwannoma unrelated to the cranial nerves
Ananth P Abraham1, Sauradeep Sarkar1, Pavithra Mannam2, Geeta Chacko3, Ari G Chacko1
1 Department of Neurological Sciences, Christian Medical College, Vellore Tamil Nadu, India
2 Department of Radiology, Christian Medical College, Vellore Tamil Nadu, India
3 Department of Pathology, Christian Medical College, Vellore Tamil Nadu, India
|Date of Web Publication||23-Jul-2019|
Dr. Ari G Chacko
Department of Neurological Sciences, Christian Medical College, Vellore - 632 004, Tamil Nadu
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Abraham AP, Sarkar S, Mannam P, Chacko G, Chacko AG. A rare case of a giant tentorial bicompartmental cystic schwannoma unrelated to the cranial nerves. Neurol India 2019;67:932-3
|How to cite this URL:|
Abraham AP, Sarkar S, Mannam P, Chacko G, Chacko AG. A rare case of a giant tentorial bicompartmental cystic schwannoma unrelated to the cranial nerves. Neurol India [serial online] 2019 [cited 2019 Dec 10];67:932-3. Available from: http://www.neurologyindia.com/text.asp?2019/67/3/932/263175
Intracranial schwannomas unrelated to cranial nerves are exceedingly rare. Of these, tentorial schwannomas are an even smaller subset with only 14 cases having been reported till date.
A 35-year old woman presented with headache and vomiting 4 months earlier, followed by gait ataxia. On examination, she had bilateral papilledema and left cerebellar signs with no cranial nerve deficits. Magnetic resonance imaging (MRI) of the brain with contrast [Figure 1] showed a mass measuring 5.4 × 4.3 × 7.6 cm, predominantly cystic and straddling the tentorium. It was bicompartmental in nature, but appeared as though it had originated from within the leaves of the tentorium with a sheet of tentorial dura completely encasing the tumor despite it reaching such large proportions. It contained internal septations with fluid–fluid levels. The wall of the tumor enhanced on contrast administration. The gadolinium uptake was most marked along the tumor–tentorium interface, and the transtentorial configuration resulted in a unique double-dural tail sign. There was a peripheral hypointense rim on susceptibility weighted imaging, and blooming within the cyst, indicating recent hemorrhage.
|Figure 1: MRI brain showing a giant cystic tentorial tumor with both infratentorial and supratentorial extension: (a) T2-weighted axial image showing a posteriorly located tentorial tumor with fluid–fluid levels, (b) T2-weighted coronal image showing the tentorial dura splitting to accommodate the tumor, (c) post-contrast T1-weighted axial image showing contrast enhancement of the wall and internal septations within the tumor, and (d) axial susceptibility weighted image showing hemosiderin staining of the cyst wall|
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Although atypical in appearance, our initial diagnosis was that of a cystic meningioma. We performed a left paramedian suboccipital craniectomy and occipital craniotomy to approach the tumor. It had a yellowish firm wall and contained xanthochromic fluid. At surgery, we confirmed that the tumor arose from within the leaves of the tentorium with no infiltration through the dura into the occipital lobe or cerebellum. We removed the tumor completely. She did not recruit any new neurological deficits postoperatively and made an uneventful recovery. The histopathology of the tumor was reported as a schwannoma [Figure 2]. Her latest MRI of the brain done 9 years after surgery showed no tumor recurrence [Figure 2].
|Figure 2: Hematoxylin and eosin stain (90×) showing (a) Antoni A areas composed of compactly arranged tumor cells. On follow-up MRI, 9 years after surgery; (b) T2-weighted coronal image showing gliosis in the left cerebellar hemisphere and the occipital lobe with a well-defined defect in the tentorium cerebelli, (c and d) post-contrast T1-weighted axial and sagittal images showing no evidence of recurrent tumor|
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It has been proposed that such schwannomas which are completely unrelated to a cranial nerve originate from ectopic Schwann cells born out of disordered embryogenesis. Another hypothesis is that they arise from the tentorial nerve, which is a branch of the ophthalmic nerve that runs between the two layers of the tentorial dura and forms a plexus., The tumor had an unusual appearance, occupying the supra- and infratentorial compartments but still remaining within the dura. This growth pattern has been reported in four other patients.,,, On reviewing the other cases reported in the literature, the radiological appearance seems to be typical, with a clearly defined dural margin evident around the entire tumor and the tendency of the tumor to be predominantly cystic. The dural tail sign, which was believed to be exclusive to meningiomas, was noted in almost all the cases reported till date.
Schwannomas must, therefore, always be considered in the differential diagnoses of tentorial tumors. Prior knowledge of their radiological characteristics will help us make the correct preoperative diagnosis.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]