Intracranial subfrontal schwannoma

Isolated schwannoma of the olfactory groove: a case report

Introduction Schwannoma of the olfactory groove is an extremely rare tumor that can share a differential diagnosis with meningioma or neuroblastoma.

Objectives The authors present a case of giant schwannoma involving the anterior cranial fossa and ethmoid sinuses.

Case Report The patient presented with a 30-month history of left nasal obstruction, anosmia, and sporadic ipsilateral bleeding. Computed tomography of the paranasal sinuses revealed expansive lesion on the left nasal cavity extending to nasopharynx up to ethmoid and sphenoid sinuses bilaterally with intraorbital and parasellar extension to the skull base. Magnetic resonance imaging scan confirmed the expansive tumor without dural penetration. Biopsy revealed no evidence of malignancy and probable neural cell. Bifrontal craniotomy was performed combined with lateral rhinotomy (Weber-Ferguson approach), and the lesion was totally removed. The tumor measured 8.0 × 4.3 × 3.7 cm and microscopically appeared as a schwannoma composed of interwoven bundles of elongated cells (Antoni A regions) mixed with less cellular regions (Antoni B). Immunohistochemical study stained intensively for vimentin and S-100.

Conclusion Schwannomas of the olfactory groove are extremely rare, and the findings of origin of this tumor is still uncertain but recent studies point most probably to the meningeal branches of trigeminal nerve or anterior ethmoidal nerves.

Schwannomas of the sinonasal tract and anterior skull base: a systematic review of 94 cases

BACKGROUND

Schwannomas of the anterior skull base (ASB) and sinonasal tract are extremely rare. These lesions mimic other pathologies such as olfactory groove meningiomas, hemangiopericytomas, and esthesioneuroblastomas. Because of their low incidence, ASB and sinonasal tract schwannomas have not been well characterized. A systematic review of ASB and sinonasal tract schwannomas was conducted to further elucidate the presentation and surgical management of these lesions.

METHODS

A MEDLINE/PubMed search was performed, identifying 71 articles representing 94 cases of ASB and sinonasal schwannomas. Each case was analyzed for demographics, clinical presentation, anatomic location, radiographic features, and surgical treatment.

RESULTS

In 94 patients with ASB and sinonasal schwannomas, 44 (46.8%) were exclusively sinonasal, 30 cases (31.9%) were exclusively intracranial, 12 (12.8%) were primarily intracranial with extension into the paranasal sinuses, and 8 (8.5%) were primarily sinonasal with intracranial extension. Headaches and nasal obstruction were the most common presenting symptoms occurring in 30.9 and 29.8% of cases, respectively. Magnetic resonance imaging typically showed a hyperintense mass on T2-weighted imaging (70%) and hypointense (41%) on T1-weighted imaging. Most patients underwent surgical gross total resection via craniotomy, endoscopic endonasal approach, rhinotomy, or other sinonasal approaches. Recurrence occurred in three cases ranging from 4 months to 13 years. Postoperative complications included cerebral spinal fluid leakage, bacterial meningitis, epidural hematoma, and pneumocranium.

CONCLUSION

ASB and sinonasal schwannomas are rare lesions and should be considered in the differential diagnosis of ASB masses involving the cribriform plate with sinonasal extension. Gross total resection of these lesions should be considered the goal of operative management.

Anterior fossa schwannoma mimicking an olfactory groove meningioma: case report and literature review

Intracranial schwannomas not associated with cranial nerves account for less than 1% of surgically treated schwannomas of the central and peripheral nervous system. With only 45 cases reported to date, subfrontal schwannomas are very rare tumors, leaving the issue of their origin controversial. A 66-year-old woman presented with a 1-year history of progressive headaches. Clinical examination revealed hypoesthesia of the nasal tip. CT-scan and MRI studies revealed a large subfrontal tumor thought preoperatively to be a meningioma. Intraoperatively, a large extra-axial tumor arising from the floor of the right frontal fossa was encountered. Histopathology identified the tumor as a schwannoma. This current case gives strong clinical presumption of an origin from the anterior ethmoidal nerve. We reviewed the literature in order to establish the epidemiology of these tumors, from which there appear to be divergent profiles depending on tumor origin and histology. Despite close similarities with olfactory groove meningiomas, patient history and radiological findings provide substantial evidence for differential diagnosis.

The puzzling olfactory groove schwannoma: a systematic review

We systematically reviewed the literature concerning the anterior cranial fossa schwannomas to understand their pathogenesis, determine their origin, and standardize the terminology. We performed a MEDLINE, EMBASE, and Science Citation Index Expanded search of the literature; age, gender, clinical presentation, presence or absence of hyposmia, radiological features, and apparent origin were analyzed and tabulated. Cases in a context of neurofibromatosis and nasal schwannomas with intracranial extension were not included. Age varied between 14 and 63 years (mean = 30.9). There were 22 male and 11 female patients. The clinical presentation included seizures (n = 15), headache (n = 16), visual deficits (n = 7), cognitive disturbances (n = 3), and rhinorrhea (n = 1). Hyposmia was present in 14 cases, absent in 13 cases (39.3%), and unreported in five. Homogeneous and heterogeneous contrast enhancement was observed in 14 and 15 cases, respectively. The region of the olfactory groove was the probable site in 96.5%. Olfactory tract could be identified in 39.3%. The most probable origin is the meningeal branches of trigeminal nerve or anterior ethmoidal nerves. Thus, olfactory groove schwannoma would better describe its origin and pathogenesis and should be the term preferentially used to name it.

Olfactory ensheathing cell tumor arising from the olfactory mucosa

We report a rare case of olfactory ensheathing cell tumor. A female presented a large soft mass extending medially to the olfactory cleft and laterally to the middle meatus in the left nasal cavity. Imaging studies confirmed a cystic mass extending superiorly into the frontal lobe, indicating that the tumor arouse from the olfactory mucosa. A subtotal resection was achieved through an endoscopic endonasal approach without operative complications. Immunohistochemically constituent cells were diffusely positive for S-100 protein, but olfactory ensheathing cell tumor was diagnosed by negative staining for Leu7 (CD57). This case indicates that olfactory ensheathing cell tumor should be included in differential diagnoses for the olfactory cleft tumors.

Solitary olfactory schwannoma without olfactory dysfunction: a new case report and literature review

Schwannomas are rare and seldom extend into the anterior cranial fossa. Herein, we report a case of schwannoma arising from the olfactory groove in a 16-year-old girl who presented with generalized seizures without olfactory dysfunction or other neurologic deficits. Computerized tomography (CT) scan showed a large mass with abundant calcification located in the olfactory groove, which was confirmed as a schwannoma by histology and totally resected via basal subfrontal approach. The presentation, imaging findings and histogenesis of the tumor are discussed along with a review of the pertinent literature.

Olfactory schwannoma

We report a case of olfactory schwannoma with calcification. Intraoperative findings indicated that the tumour originated from the olfactory groove. Intraoperative findings of previous studies have not indicated a clear relationship between subfrontal schwannoma and the olfactory nerve, which seems strange, given the association between tumours and cranial nerves at other sites. We suggest this observation has not been reported because the growing olfactory schwannoma changes the local morphology, affecting the appearance of the olfactory nerve.

Subfrontal schwannoma: a case report and literature review

Subfrontal schwannomas are rare and usually misdiagnosed preoperatively. We present the third reported case of a schwannoma arising from the olfactory nerve. The neuroradiological and pathological features of the case, as well as the origin of the tumour are discussed.

Malignant Peripheral Nerve Sheath Tumor in the Anterior Skullb Base Associated With Neurofibromatosis Type 1-Case Report-

A 36-year-old man presented with a tumor in the anterior skull base manifesting as headache and visual disturbance. Neurofibromatosis type 1 (NF-1) was identified in early childhood in the patient, and also in his father. Subtotal excision of the tumor was performed, leaving the portion extending outside of the cranium. The histological diagnosis was malignant peripheral nerve sheath tumor. Local radiotherapy was instituted postoperatively. Facial paralysis and dysphagia appeared 7 months after the first operation. Magnetic resonance imaging revealed new lesions in the lateral ventricle and around the brainstem. These tumors were also subtotally excised, but the patient died 10 months after the first operation. The tumor very likely originated from the meningeal branch of the trigeminal nerve. Treatment of such tumors developing inside the cranium should include the widest resection possible, followed by irradiation of the entire neuraxis including the spinal cord to inhibit dissemination through the cerebrospinal fluid. Treatment should be started as quickly as possible if the tumor is associated with NF-1, because of the poor prognosis associated with this condition.

Subfrontal Schwannoma Without Hyposmia-Case Report-

A 44-year-old man presented with a rare subfrontal schwannoma with headache. He had undergone radiation therapy for a pineal lesion 30 years previously, but the histology was not verified. On admission, neurological examination revealed no focal deficits including hyposmia. Computed tomography demonstrated a mass measuring 5 x 3 cm in the right anterior cranial fossa. Magnetic resonance imaging revealed a heterogeneously enhanced mass with multiple cysts. The tumor, which was clearly separable from the surrounding normal brain, was totally resected through a right frontal craniotomy. There was no adhesion between the tumor and the olfactory groove or cribriform plate. The frontal base dura was suspected to be the tumor attachment. The patient was discharged without hyposmia. Histological examination revealed a typical pattern of schwannoma consisting of Antoni type A and type B. Immunohistochemical staining was positive for S-100 protein but negative for epithelial membrane antigen. Subfrontal schwannoma not associated with the olfactory groove or cribriform plate is extremely rare. The operative findings and absence of hyposmia suggest that the meningeal branch of the trigeminal nerve was the origin of the tumor. However, the possibility of radiation-induced reactive Schwann cells cannot be excluded.

[Olfactory groove schwannoma: case report]

Intracranial schwannoma not related to cranial nerves are unusual and rarely found in the subfrontal region. We report a case of olfactory groove schwannoma in a 27-year-old male, who presented with anosmia and headache initiated one year ago. At admission, bilateral papilledema was noted with absense of motor deficits or cranial nerves abnormalities. Cranial computed tomography (CT) revealed a bifrontal multicystic isodense enhancing mass lesion causing a frontal ventricular horn compression. Radiological features resembled that of a cystic olfactory groove meningioma. Decompressive bifrontal craniotomy was done. One month later, CT demonstrated a homogeneously contrast-enhancing mass in the olfactory groove region who extended into the left nasal cavity. Magnetic resonance imaging did not add more informations. A second surgical procedure was done through a nasoethmoidal approach with incomplete resection of the lesion. The complete tumor resection was only possible in a third surgery through another bifrontal approach. The hystopathological diagnosis of schwannoma was performed by conventional methods and confirmed by immunohistoquemical staining for S-100 protein. The rarity of this tumor and his clinical, radiological and histological aspects justify this publication.