Intracerebral schwannoma clinically and radiologically mimicking meningioma

Scoring system for intraoperative diagnosis of intracranial schwannoma by squash cytology

OBJECTIVE

To assess the utility of a newly developed squash cytology (SC)-based scoring system for accurate intraoperative diagnosis of schwannoma.

METHODS

We first compared SC-based and frozen section (FS) diagnoses with final pathological diagnoses of schwannoma (16 cases), meningioma (39 cases) and low-grade astrocytoma (16 cases). Then, by logistic regression modeling, we identified features of SC preparations that were independently predictive of schwannoma. To develop a diagnostic scoring system, we assigned one point to each feature, and performed receiver operating characteristic analysis to determine the score cut-off value that was most discriminatory for differentiating schwannoma from the other tumour types. We then compared accuracy, sensitivity, and specificity of diagnosis before and after the application of the scoring system.

RESULTS

Overall diagnostic concordance rates for SC and FS were almost the same, at 73.2% (52/71) and 77.5% (55/71 cases), respectively. Of the 16 SC features entered into the analysis, the following nine were found to independently predict schwannoma, and were thus incorporated into the scoring system: smooth cluster margins, few or no isolated tumour cells, fibrillary stroma, spindle-shaped nuclei, parallel arrangement of stroma, parallel arrangement of nuclei, presence of anisonucleosis, absence of nucleoli, and hemosiderin deposition. A cut-off score of four items yielded the best sensitivity, specificity and predictive values for prediction of schwannoma. Use of the scoring system improved accuracy of intraoperative diagnosis from 80.3% to 94.4%, sensitivity from 56.2% to 93.8%, and specificity from 87.3% to 94.5%.

CONCLUSION

Our proposed SC-based scoring system will increase accuracy of intraoperative diagnosis of schwannoma vs non-schwannoma tumours.

Anterior skull base olfactory tumours, which is what? A case report and review

Intracranial schwannomas not originating from cranial nerves are rare. In this paper, we report a case of a 50-year-old male who presented with worsening headaches, diplopia and nausea over two years. Radiological imaging revealed a large tumour arising from the olfactory groove region with a preoperative diagnosis of olfactory groove meningioma (OGM). Intraoperatively, the tumour originated from the region of the attachment of the falx to the crista galli. The patient recovered without complication and histopathology reported an unexpected diagnosis of WHO Grade 1 schwannoma. However, as olfactory groove schwannomas (OGSs) cannot be distinguished from olfactory ensheathing cell tumours (OECTs), it is possible that the tumour could have been either an OGS or an OECT. Distinguishing between OGSs, OECTs and OGMs preoperatively is difficult. OGMs exhibit distinct histopathological features from OGSs/OECTs, however, OGSs and OECTs currently cannot be distinguished from each other. Here, we review the literature to discuss the differentiating features and cellular origins of these three tumours.

Seizures and Blurred Vision as Initial Presentation of Intracerebral Schwannoma: A Rare Tumor of the Brain

Schwannomas are the most common tumor of peripheral nerves which are arising from Schwann cells and are benign in their nature. Intracranial schwannoma accounts for between 5 and 8% of intracranial tumors, whereas intracerebral schwannoma, a rare disease, accounts for <1% of intracranial schwannomas. Intracerebral schwannoma has no specific clinical manifestation, and it is not classified by age. Here, we are reporting a case of an 18-year-old male who presented with attacks of seizures. MR imaging studies were done and showed right parieto-occipital cortical and subcortical mass lesion with intense enhancement and significant vasogenic oedema with mass effect on the subjacent sulci. The tumor was surgically removed through a right occipital craniotomy. Histological findings confirmed the diagnosis of schwannoma.

Supratentorial extraparenchymal schwannoma mimicking parasagittal meningioma: A rare case report

Background:

Intracranial schwannomas not related to cranial nerves are very rare. Young age, no known history of neurofibromatosis, and seizure as initial symptom have been reported to be associated with intraparenchymal schwannoma.

Case Description:

We report a case of supratentorial parasagittal schwannoma in the right frontal region presenting with seizure episode in a 70-year-old man. Computed tomography and magnetic resonance imaging showed a right frontal solid, enhancing extra-axial lesion based on anterior and middle third junction of superior sagittal sinus. The preoperative diagnosis was right parasagittal meningioma, however, the microscopic examination of the mass showed the characteristic pattern of cellular Antony A pattern. Immunohistocemically, the tumor stained positive for S-100 protein but negatively for epithelial membrane antigen and glial fibrillary acidic protein. These findings are consistent with schwannoma. Cysts, calcification, and peritumoral edema are common in intracerebral schwannoma, which were not seen in our case.

Conclusion:

On the basis of clinical presentation and radiological appearances, schwannoma in unusual sites can easily be mistaken for meningiomas; immunochemistry plays an important role in differentiating them. Till date, to the best of our knowledge, this is the second reported case of schwannoma mimicking meningioma in parasagittal location.

"Pure" Suprasellar Schwannoma Presented with Communicating Hydrocephalus: A Case Report

Schwannoma is a benign peripheral nerve sheath tumor originating from Schwann cells. Most intracranial schwannomas arise from vestibular nerve and schwannoma in the suprasellar region is extremely rare. A 64-year-old man presented with walking disturbance and blurred vision for three months. Lateral hemianopsia in the left eye and brachybasia were observed. Magnetic resonance imaging revealed a suprasellar tumor with strong contrast enhancement associated with communicating hydrocephalus. The cerebrospinal fluid tap test improved gait disturbance. Hypothalamic stimulation test revealed hypo-reaction of GH, FSH and LH. After ventriculo-peritoneal shunting, the tumor was totally removed via a bilateral front-basal approach with a clinical diagnosis of craniopharyngioma. No adhesion was observed between the tumor and surrounding structures such as meninges and brain. The histopathological diagnosis was schwannoma. Here we report a case of suprasellar schwannoma associated with communicating hydrocephalus that has not ever been previously reported, with special reference to its pathogenesis.

Microcystic/Reticular Schwannoma of the Frontal Lobe: An Unusual Occurrence

Schwannoma is a benign peripheral nerve sheath tumor that typically involves cranial nerves of the head and neck region. Intraparenchymal occurrence of this tumor is uncommon. Even rarer in this site is the microcystic/reticular pattern of schwannoma. This histologic variant, first described in 2008, has a predilection for visceral organs. Herein, we report the first case of microcystic/reticular schwannoma of the frontal lobe.

Supra and infratentorial ectopic schwannoma mimicking a meningioma

We report the case of a supra and infratentorial ectopic schwannoma, mimicking a meningioma, that was surgically resected on a 75-year-old man, with a history of progressive visual loss and headaches. MRI was in favour of an occipital, cystic, tentorial-based meningioma extending to the posterior fossa, with signs of intratumoral haemorrhage. This is a unique case because of the rare type of lesion, in a very atypical location, completely unexpected by the preoperative imaging analysis, and to the best of our knowledge it is the oldest patient reported in the literature with this kind of tumour.

Diffuse cerebral vasospasm after resection of schwannoma: a case report

BACKGROUND

The etiology of vasospasm after brain tumor resection remains unclear. This is the first report of diffuse cerebral vasospasm following resection of a schwannoma located in the left portion/part of the ventral medulla oblongata.

CASE PRESENTATION

A 16-year-old boy presented with dizziness and projectile vomiting without apparent cause three months before admission. Magnetic resonance imaging revealed a space-occupying lesion in the left portion of the ventral medulla oblongata. The tumor was completely resected. Pathological examination was consistent with diagnosis of schwannoma. Three days after surgery, the patient was in an unconscious state. Magnetic resonance angiography revealed the occurrence of cerebral vasospasm, with ischemic infarction and segmental cerebrovascular stenosis. Seven days after surgery, dehydration therapy was carried out and decompressive craniectomy was performed in the frontal and temporal areas. Despite treatments, the patient was in a persistent vegetative state after surgery, with normal vital signs.

CONCLUSION

This was an uncommon occurrence of diffuse cerebral vasospasm following the resection of schwannoma. Appropriate management of this condition is uncertain, but aggressive treatments including expansion of blood volume and relief of spasm should be performed to treat postsurgery vasospasm.

Intracerebral schwannoma mimicking meningioma: case report

Intracranial schwannomas account for 8% of all primary brain tumors, approximately 80-90% of them being seen in the cerebellopontine angle in relation to the vestibular nerve. Schwannomas arising within brain parenchyma, unrelated to the cranial nerves, are extremely rare. To our knowledge, only 73 cases of intracerebral schwannoma have been described in the English-language literature so far,1-5 but only six cases of intracerebral schwannoma mimicking meningioma have been reported1-3 and there have been few reports regarding neuroradiological findings. Disagreement remains concerning the histogenesis of these tumors.

Supratentorial intracerebral schwannoma : its fate and proper management

Intracerebral schwannomas are rare and there have been none reported in Korea. We present the case of a 25-year-old man with newly developed right-side weakness and recent seizure aggravation. His seizures started approximately 9 years prior to admission. At that time, a 1 cm diameter intra-axial enhancing mass at the left precentral gyrus was found on magnetic resonance image (MRI). After 9 years of observation and treatment with antiepileptic medication, an MRI taken due to symptom aggravation revealed peri-tumoral cyst formation with tumor enlargement. The tumor was surgically removed. Subsequently, right-side weakness diminished and there was good seizure control. Pathologic diagnosis was schwannoma. Schwannoma is a very rare tumor and there are no pathognomonic findings on radiologic images; thus, it is challenging to make a correct diagnosis. However, considering the natural course and excellent prognosis after surgical treatment of this kind of intra-axial mass with benign features, early surgery for diagnosis and proper treatment is highly recommended.

Supratentorial brain schwannomas: an uncommon location for a common tumour

INTRODUCTION

Intracranial schwannomas not related to cranial nerves are uncommon brain tumours. Such tumours account for less than 1% of all surgically treated schwannomas. Only 79 cases have been reported in the literature.

METHODS

We describe two cases treated in our centre. The patients are young women with seizures as a presenting symptom. Both underwent surgery with the presumptive diagnosis of benign brain tumour. Histopathological examination revealed the certain diagnosis of Schwannoma.

RESULTS

Good outcome was achieved with total excision of the tumour. Based on the literature, demographic data, clinical aspects, imaging features and theories on the possible origin of this rare tumour are discussed.

CONCLUSIONS

These tumours should be included in the differential diagnosis of supratentorial benign tumours in young adults. Total excision, whenever possible, is the treatment of choice.

Intracerebral schwannoma presenting as classic temporal lobe epilepsy

Schwannomas of the brain parenchyma are extremely rare, occurring mostly in children and young adults. Fewer than 50 cases have been reported in the English-language literature. Isolated temporal lobe epilepsy is a rare presentation of intracerebral schwannomas, with only 2 reported cases. The authors present the case of a 51-year-old woman with a 4-year history of medication-refractory seizures, which were localized on electroencephalography to the right temporal lobe. Magnetic resonance imaging identified a mildly space-occupying, T2 hyperintense, and inhomogeneously enhancing mass in her left mesial temporal lobe. Histological, immunohistochemical, and electron microscopy examinations of the surgical specimen established a diagnosis of intracerebral schwannoma. Accurate diagnosis of intracerebral schwannomas is essential, particularly in younger patients, given the lesions' nature, amenity to resection, favorable long-term prognosis, and broad radiological differential. The etiology of these lesions remains unknown, and multiple proposed theories are reviewed.

Meningial perineurioma: a benign peripheral nerve sheath tumor in a previously unrecognized central nervous system location, mimicking meningioma

Perineurioma is an uncommon, mostly benign, spindle-cell tumor of peripheral nerve sheath origin with a predilection for the soft tissues. Although increasing awareness points to the sites of involvement by perineurioma possibly being as ubiquitous as those frequented by schwannian tumors, only one intracerebral example has been described to date. We report on a surgically resected perineurioma of the falx cerebri in an 86-year-old woman. Preoperative imaging showed an enhancing extraaxial mass of 6 cm × 5.7 cm × 3.7 cm. Histologically, the tumor consisted of a proliferation of spindle cells interwoven by a lattice of basal lamina. Alongside a prevailing soft tissue perineurioma pattern, sclerosing and reticular areas were seen as well. Tumor cells coexpressed EMA and GLUT-1, and a minority immunoreacted for smooth muscle actin. Pericellular basal lamina was decorated with collagen type IV. No staining for S100 protein was detected. Mitotic activity was virtually absent, and the MIB1 labeling index averaged 2%. Ultrastructural examination revealed abundant pinocytotic vesicles within and conspicuous tight junctions between slender cytoplasmic processes which, in turn, were encased by discontinuous basal lamina. FISH analysis confirmed loss of at least part of one chromosome 22q. This observation calls attention to perineurioma as a novel item in the repertoire of low-grade meningial spindle cell neoplasms, in the differential diagnostic context of which it is apt to being misconstrued as either meningioma, solitary fibrous tumor, or neurofibroma. Confusion with the latter bears the risk of overgrading innocuous features of perineurioma as criteria for malignancy.

Schwannoma with tentorial attachment in the cerebellopontine angle mimicking a meningioma

Intracranial schwannoma not associated with the cranial nerves is rare. It is also an intriguing neoplasm since the Schwann cell is not native to the central nervous system. To date only four cases of intracranial schwannoma arising from the tentorium have been reported. We present a 49-year-old woman who harboured a schwannoma with a tentorial attachment in the right cerebellopontine angle and describe the relevant clinical, radiological and pathological findings. In addition, we briefly review the main hypotheses for the origin of this neoplasm and highlight its resemblance to meningioma and inclusion as a differential diagnosis.