Optic sheath schwannomas: report of two cases

INTRODUCTION: Schwannomas are benign tumors that arise from Schwann cells in the peripheral nervous system. The vestibular division of the VIIIth cranial nerve is the nerve segment most commonly affected, the trigeminal nerve root being the next most frequently affected. Although schwannomas of other cranial nerves are very rare, these nerves do have myelinated sheaths composed of Schwann cells and are potential sites for intracranial schwannomas. However, previous studies have suggested that the term 'schwannoma' should not be applied in the case of optic nerve pathology, although two cases of optic nerve sheath schwannoma have been reported to our knowledge. PURPOSE: The purpose of this paper is to report two cases of the exceedingly rare entity of optic sheath schwannoma and to discuss its histopathogenesis.     

Thoracic Intramedullary Schwannoma Accompanying by Extramedullary Beads-Like Daughter Schwanommas

Thoracic intramedullary schwannomas are rare spinal cord tumors. Most of these tumors have been reported as a single lesion in the spinal cord. The authors report the first case of intramedullary schwannoma accompanying by extramedullary beads-like daughter masses of the thoracic spine. A 68-year-old male presented with walking disturbance and decreased sensation below T10 dermatome. Imaging workup revealed an intramedullary mass at T6 and T7. T6 and T7 laminectomy and mass removal were performed. Intraoperatively, extramedullary beads-like daughter masses along the nerve roots adjacent to intramedullary mass were identified. Total removal of intramedullary lesion and partial resection of extramedullary masses were done. Histological analysis confirmed the diagnosis of schwannoma. The patient could ambulate independently at postoperative 1 month without any neurological sequelae. The authors experienced a surgical case of intramedullary schwannoma accompanying by extramedullary beads-like same pathologies in the thoracic spine.     

Intraventricular schwannoma in a 15-year-old adolescent: a case report

Introduction Schwannomas are benign tumors that originate from the myelin-forming Schwann cells of peripheral nerves or at the Obersteiner–Redlich zone of the vestibular division of the eighth cranial nerve. Intraventricular schwannomas are rare, particularly among children. Discussion This case report illustrates a right occipital horn schwannoma in a 15-year-old adolescent boy who was successfully treated with surgical resection and discusses the possible origins of the tumor in this unique location.     

Lectin histochemistry of normal and neoplastic peripheral nerve sheath

Lectin binding patterns of 31 schwannomas and 6 neurofibromas were examined using 12 lectins, and the results were compared with those of normal peripheral nerves. Tumors obtained from 10 cases of neurofibromatosis and 4 recurrent schwannomas were included. Changes of glycoconjugates were observed in association with a neoplastic transformation of Schwann cells; Arachis hypogaea (PNA) staining after neuraminidase treatment seen in normal Schwann cells was reduced in schwannoma of Antoni type A, and bindings with Glycine max (SBA) and Helix pomatia (HPA) after sialic acid removal, which were not seen in normal Schwann cells, appeared in schwannoma cells. Intensities of staining of tumor cells with each lectin were higher in Antoni type B than those in Antoni type A. No differences in lectin binding patterns were observed between schwannomas in patients with neurofibromatosis or recurrent schwannomas and ordinary, primary schwannomas in patients without stigmata of neurofibromatosis. Lectin binding patterns of Schwann cells and perineurial cells in neurofibroma were almost similar to those in normal peripheral nerves with an exception of faint stain of Schwann cells with HPA after neuraminidase pretreatment. This result suggests differences in extent of differentiation between schwannoma cells and neoplastic Schwann cells in neurofibroma. Specific PNA binding to perineurial cells in neurofibroma indicates the significance of this lectin as a marker of these cells.Supported in part by Grants-in-Aid from the Japanese Ministry of Education, Science and Culture     

Giant benign schwannoma on scalp causing 'double-head'

Abstract- Schwannomas are tumors derived from Schwann cells. They are usually small and comparatively rare on scalp. A 25-year old woman presented with huge mass on posterior side of the scalp that gave the appearance of 'double-head'. The mass was excised and reconstruction was achieved by primary closure. Histology proved to be a benign schwannoma. The patient is well at 6-months of follow up. Giant benign schwannoma on scalp is extremely rare. Clinicians that came across the giant tumors of the scalp should suspect this possibility as these tumors have favorable prognosis.     

Frontal intraparenchymal schwannoma

Intraparenchymal schwannomas are rare. The usual presentation is of a classical intracranial mass lesion. We report a frontal intraparenchymal schwannoma in a pediatric patient with a history of seizure. An MRI scan revealed a uniformly enhancing tumor with perilesional edema. This type of tumor is rarely found in this location. It is important to recognize and distinguish a schwannoma from other more common frontal brain tumors as the outcome is good and recurrence is rare.     

Primary intraventricular schwannomas

Schwann cell tumors arising within the neuraxis and in an intraventricular location are an exceedingly rare tumor entity of the brain. The authors present the first case of a cellular intraventricular schwannoma occurring in the fourth ventricle. The pertinent literature is reviewed.A 71-year-old female was admitted to the hospital with an incidental finding of a ventricular tumor. Computed tomography scanning and magnetic resonance imaging revealed a solitary contrast enhancing exophytic mass lesion within the fourth ventricle. Microsurgical excision via a midline suboccipital craniotomy and tonsillo-nodular approach led to complete tumor removal. Subsequent histopathological examination confirmed the diagnosis of an unsuspected primary intraventricular cellular schwannoma.A unique case of an initially unexpected benign schwannoma arising from the fourth ventricle that could be successfully treated by microsurgery and finally confirmed by histopathological analysis with excellent patient outcome is presented. Although highly uncommon, Schwann cell tumors of both benign and malignant nature may present as ventricular lesions and should be included as a differential diagnosis in patients with either solely intraventricular masses or intra- and extraaxial tumors with extension to the ventricles.     

Melanotic progonoma of the skull in infancy

Introduction  Melanotic progonoma or melanotic neuroectodermal tumor is a rare tumor in infancy. This lesion has to be considered in the differential diagnosis of benign or malignant lesions of calvarium. Case report  The authors present a case of a 4-month-old infant with left retroauricular mass. The patient had a subcutaneous mass that is fixed to the underlying skull. CT and MRI scans showed left occipitotemporal expansile mass. The tumor was removed by surgery. A tumor, brownish-black in color, was diagnosed as melanotic progonoma. The patient remained symptom-free for the last 2 years after complete surgery. Discussion  Extracranial subcutaneous masses involving the skull are uncommon in infants. Benign or malignant lesions may occur as lumps on calvarium. Physical examination and some laboratory findings are helpful in the assessment of patient. Benign or malignant lesions can be differentiated by craniography, CT, or MRI scans, but exact diagnosis of melanotic progonoma is made by histopathology and immunostaining, as was in the presented case. Cranial vault progonomas have a better outcome by complete surgery. The tumors usually do not recur in long-term period.     

第四脑室神经鞘瘤的临床特点及手术治疗并文献复习

目的探讨原发性第四脑室神经鞘瘤的临床特征及手术方法。方法分析1例原发性第四脑室神经鞘瘤手术治疗患者的临床资料,并结合文献分析该病的临床特点和手术方法。结果患者为女性,53岁,表现为剧烈头痛、吞咽困难、共济失调、四肢无力等症状,影像学示第四脑室巨大肿瘤,合并脑积水。手术采用经枕下正中小脑延髓裂入路,肿瘤镜下获得全切除,术后病理诊断为神经鞘瘤。术后随访8个月,未见肿瘤复发。结论尽管脑室内神经鞘瘤罕见,且诊断困难,但该类型肿瘤为良性肿瘤,其边界清楚。因此,手术若能获得有效的全切除,远期预后良好。     

Epithelioid schwannomas of the acoustic nerve

Epithelioid schwannomas occur predominantly in relation to peripheral nerves and are associated with histological and clinical malignancy. However, a variant of the epithelioid schwannoma involving cranial nerves is extremely rare. In this study we report three cases of epithelioid schwannomas originating from the acoustic nerves and located in the cerebello-pontine angles. In the first case, the tumor was histopathologically entirely solid and demonstrated biphasic pattern with both spindle-shaped cells and a population of round or polygonal epithelioid cells. The second one consisted of the smaller part exhibiting typical Antoni B and A tissue and large areas containing clusters and bundles of epithelioid cells. Purely epithelioid schwannoma composed predominantly of cords or nests of round and polygonal epithelioid cells were observed in the third case. All schwannomas revealed marked polymorphism and nuclear hyperchromasia. Immunohistochemical studies showed a diffuse, strong positivity for S-100 protein in the cytoplasm of the spindle and epithelioid tumor cells. These two populations of cells were positively stained for vimentin, but were negative for EMA, cytokeratin and HMB45. Patchy GFAP-immunoreactivity was also noticed at the peripheral parts of the tumors. The authors discuss differential diagnosis of this unusual variant of schwannoma in relation to malignant transformation of the epithelioid component.     

Laryngeal plexiform schwannoma as first symptom in a patient with neurofibromatosis type 2

Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder characterized by bilateral vestibular schwannomas. The initial symptoms of NF2 are usually hearing loss and tinnitus caused by vestibular schwannomas. Although other intracranial, spinal, or skin tumors also occur in NF2, laryngeal lesions are very rare. We report a rare case of NF2 with laryngeal plexiform schwannoma as first symptom. A 38-year-old man presented with a smooth-surfaced submucosal supraglottic mass. Two round masses in the left chest wall and left supraclavicular fossa were noted incidentally during investigation of the laryngeal mass. Magnetic resonance imaging (MRI) findings for these masses were identical to those of the laryngeal mass. No typical symptoms related to NF2 were identified. Histologically, the laryngeal tumor represented plexiform schwannoma. We thus considered that the two round masses in the left chest wall and left supraclavicular fossa might also represent plexiform schwannomas. NF2 was suspected, as a high incidence of multiple plexiform schwannomas has been suggested for patients with NF2. MRI of brain lesions demonstrated bilateral vestibular schwannomas and multiple meningiomas. Finally, NF2 with laryngeal plexiform schwannoma was diagnosed. Recognizing that multiple plexiform schwannomas could be associated with NF2 is important.     

Targeting ERK1/2 activation and proliferation in human primary schwannoma cells with MEK1/2 inhibitor AZD6244

Deficiency of the tumor suppressor merlin leads to the development of multiple tumors of the nervous system, such as schwannomas, meningiomas, and ependymomas. Due to the benign character of these tumors, classical chemotherapy is ineffective. Current therapies, surgery, and radiosurgery are local and quite invasive, thus new systemic treatments are required. We have previously described the Raf/mitogen-activated kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway activation and its role in schwannoma growth. Here, we targeted MEK1/2 known as a convergence point for multiple cascades towards ERK1/2 activation and cell proliferation, using MEK1/2 inhibitor AZD6244 (ARRY-142886; Astra Zeneca).We show that AZD6244 at low concentration completely abolished platelet-derived growth factor-DD-mediated ERK1/2 activation and cell proliferation in human primary schwannoma cells. Moreover, this drug was not toxic for either schwannoma or Schwann cells and has been reported to be safe with tolerable side effects. Thus, AZD6244 can be considered as a drug candidate for schwannoma treatment.     

Schwannoma‐like tumor in the anterior cranial fossa immunonegative for Leu7 but immunopositive for Schwann/2E

Schwannoma arising from the olfactory system, often called olfactory groove schwannoma (OGS), is rare, as the olfactory bulb and tract, belonging to the central nervous system, should lack Schwann cells. Another rare entity called olfactory ensheathing cell tumor (OECT) has been reported, which mimics clinical and radiological characteristics of OGS. Here, we report two rare cases of schwannoma‐like tumor in the anterior cranial fossa that showed negative staining for Leu7, but positive staining for Schwann/2E, and discuss their origin. Two cases of mass lesions in the anterior cranial fossa in a 26‐year‐old man and a 24‐year‐old woman were successfully removed. Morphological examination of these tumors was compatible with a diagnosis of schwannoma. Immunohistochemically, both cases were negative for Leu7, yielding a diagnosis of OECT, but were positive for the schwannoma‐specific marker, Schwann/2E. Immunohistochemical staining results in our two cases question the current assumption that OGS and OECT can be distinguished only by Leu7 staining pattern. In conclusion, the origins of OGS and OECT remain to be determined, and further studies in larger numbers of cases are needed to characterize these rare tumors in the anterior cranial fossa.     

Incidentally diagnosed giant invasive sacral schwannoma: Its clinical features and surgical management without stability

Schwannomas are benign encapsulated tumors of Schwan cells that grow slowly along the peripheral myelin nerve fibers. Sacral spinal schwannomas are very rare, and the incidence of sacral schwannoma ranges from 1-5% of all spinal schwannomas, and only around 50 cases are reported in the literature. There are 3 defined types of sacral schwannomas. These are retroperitoneal or presacral, intra osseous, and spinal schwannomas. Patients commonly present with complaints of pain and paresthesia due to the spinal schwannoma extending to extra spinal tissues. Direct x-ray, CT, MRI, and scintigraphy are used for preoperative diagnosis and treatment planning. Local recurrence and transformation to malignancy is very rare. For this reason, the frequently preferred treatments are subtotal removal of the mass or simple enucleation. In our article, we discuss the clinical features and the surgical treatment we performed without the need for stabilization in an incidentally determined giant invasive schwannoma case.Primitive sacral and presacral tumors are very rare. Spinal schwannomas constitute approximately 25% of vertebral tumors. They most commonly tend to settle in the thoracic region. They are very rarely seen in the sacral region and constitute 1-5% of all spinal schwannomas, and only around 50 cases are reported in the literature.1-3 Schwannomas are mostly benign lesions. Malignant ones are either malignant from the beginning or become malignant due to degeneration of benign schwannomas, such as is the case in neurofibromatosis type II patients. There are 3 defined types of sacral schwannomas; retroperitoneal or presacral, intra osseous, or spinal schwannomas. According to the definition by Sridhar et al,2 giant invasive spinal schwannomas are masses that invade more than 2 vertebral levels, invade vertebral bodies, and by extending posteriorly, reach the myofascial regions. For this reason, the clinical and surgical results of giant invasive type spinal schwannomas (GISS) differ slightly from typical schwannomas. The clinical diagnoses of these tumors are made by direct x-ray, CT, and MRI. The ideal treatment of GISS would be to totally remove the tumor by decompression and surgery without creating any neural complications or spinal instability, which would relieve the pressure on neural organs created by the mass and regress symptoms.3-5 Our objective in presenting this particular case is to highlight an interesting and rare presentation for incidentally diagnosed giant invasive schwannoma of the sacrum.     

PAK kinase regulates Rac GTPase and is a potential target in human schwannomas

Merlin loss causes benign tumours of the nervous system, mainly schwannomas and meningiomas. Schwannomas show enhanced Rac1 and Cdc42 activity, the p21-activated kinase 2 (PAK2) activation and increased ruffling and cell adhesion. PAK regulates activation of merlin. PAK has been proposed as a potential therapeutic target in schwannomas. However where PAK stands in the Rac pathway is insufficiently characterised. We used a novel small-molecule PAK inhibitor, IPA-3, to investigate the role of PAK activation on Rac1/Cdc42 activity, cell spreading and adhesion in human primary schwannoma and Schwann cells. We show that IPA-3 blocks activation of PAK2 at Ser192/197 that antagonises PAK's interaction with Pix. Accordingly, Pix-mediated Rac1 activation is decreased in IPA-3 treated schwannoma cells, indicating that PAK acts upstream of Rac. We show that this Rac activation at the level of focal adhesions in schwannoma cells is essential for cell spreading and adhesion in Schwann and schwannoma cells.     

Rearrangements of the intermediate filament GFAP in primary human schwannoma cells

Loss of the tumor suppressor protein merlin causes a variety of benign tumors such as schwannomas, meningiomas, and gliomas in man. We previously reported primary human schwannoma cells to show enhanced integrin-dependent adhesion and a hyperactivation of the small RhoGTPase Rac1. Here we show that the main intermediate filament protein of Schwann cells, the glial fibrillary acidic protein, is collapsed to the perinuclear region instead of being well-spread from the nucleus to the cell periphery. This cytoskeletal reorganization is accompanied by changes in cell shape and increased cell motility. Moreover, we report tyrosine phosphorylation to be enhanced in schwannoma cells, already described earlier in intermediate filament breakdown. Thus, we believe that Rac activation via tyrosine kinase stimulation leads to GFAP collapse in human schwannoma cells, and suggest that this process plays an important role in vivo where schwannoma cells become motile, unspecifically ensheathing extracellular matrix and forming pseudomesaxons.     

Clinical outcomes of resecting scarpa's ganglion during vestibular schwannoma surgery

Vestibular schwannomas are slow-growing tumors arising from the Schwann cells of the vestibular nerve. Scarpa’s ganglion, the vestibular nerve ganglion, is located within the internal auditory meatus. Surgical treatment of vestibular schwannomas carries the potential of resecting Scarpa’s ganglion along with the tumor. No prior studies have evaluated outcomes based on the presence of Scarpa’s ganglion within tumor specimens. The neurosurgery patient records were queried for patients who underwent surgical resection of vestibular schwannomas at the University of Missouri Healthcare between January 1, 2008 and December 31, 2018. Inclusion criteria consisted of minimum age of 18, imaging demonstrating an eighth nerve tumor, surgical resection thereof, and a final pathological diagnosis of WHO grade I schwannoma. Data were collected retrospectively. The histological slides of the tumors were reviewed, and the presence or absence of the ganglion was noted. Outcomes analyzed included postoperative dizziness, hearing, and facial nerve function. Fifty-two patients met inclusion criteria. Ten (19%) resected tumors contained portions of the ganglion. No difference in risk of resection of ganglion occurred based on the surgical approach (p = 0.2454). Mean follow-up duration was 24.6 months ± 26.2 standard deviation. No differences in postoperative hearing or dizziness (p = 0.8483 and p = 0.3190 respectively) were present if Scarpa’s ganglion was resected. House-Brackmann classification of facial nerve function at last follow-up was similar (p = 0.9190). Resection of Scarpa’s ganglion with vestibular schwannomas does not increase risk of post-operative dizziness, facial nerve weakness, or hearing loss.