Olfactory ensheathing cell tumor arising from the olfactory mucosa

Olfactory Groove Schwannoma or Olfactory Ensheathing cell Tumor?

BACKGROUND

Schwannomas are benign tumors that arise from Schwann cells. Rare cases are shown to arise from the olfactory nerve. The genesis of Olfactory groove schwannoma (OGSs) is still puzzling. Yusda et al hypothesized that olfactory ensheathing cell tumors (OECTs) might be the origin of OGSs.

CLINICAL PRESENTATION

Here, the authors report the case of a 59-year-old woman who presented with a paroxysmal headache for 1 year. The tumor appeared as hypointensity on T1-weighted images, hyperintensity on T2-weighted, and exhibited strong, heterogeneous enhancement. The tumor was removed through a lateral supraorbital approach. The final pathologic diagnosis was schwannoma. The postoperative period was uneventful after 4 months, and the headache disappeared.

DISSCUSSION AND CONCLUSION

OGSs and OECTs are extremely rare. There are many similarities in clinical manifestations, images, and pathologic findings. OGSs are difficult to distinguish from OECTs.

[Olfactory (subfrontal) schwannoma: case report and literature review]

BACKGROUND

Olfactory nerve schwannomas are extremely rare. Their origin is still unclear, since olfactory nerve has no Schwann cells. There are about 70 case reports of olfactory nerve schwannoma in the world literature. Original articles devoted to this issue are currently absent.

RESULTS

We present a 55-year-old patient with olfactory nerve schwannoma who underwent surgery at the Federal Center of Neurosurgery in Novosibirsk. MRI revealed extracerebral mass lesion of anterior cranial fossa base with left-sided lateralization resembling meningioma of the olfactory fossa. The patient underwent microsurgical resection of mass lesion of anterior cranial fossa base through left-sided lateral supraorbital craniotomy. The tumor macroscopically resembled schwannoma. Total resection was carried out. Considering morphological structure and immunomorphological characteristics, we verified schwannoma Grade 1.

CONCLUSION

Olfactory nerve schwannomas are rare tumors with benign histological structure. Relapses after total resection are unlikely. However, further research of this rare pathology and long-term postoperative follow-up are required.

Utility of Schwann/2E and Sox10 in distinguishing CD57-negative olfactory groove schwannoma from olfactory ensheathing cell tumor: A case report and review of the literature

We herein report a patient who was diagnosed as having olfactory groove schwannoma (OGS) which was negative for CD57 (Leu7) but positive for Schwann/2E and Sox10. A 13-year-old female with a chief complaint of headache was referred to our department due to a tumor lesion in the anterior skull base identified by magnetic resonance imaging (MRI). At the first visit, she did not exhibit altered consciousness, motor palsy, anosmia, seizures, or café au lait spots. On contrast-enhanced computed tomography (CT), a heterogeneously enhanced tumor, 50 × 45 × 50 mm in size, was observed at the anterior skull base. The left cribriform plate was thinner on bone window CT. The tumor exhibited strong, heterogeneous gadolinium enhancement on MRI as well. Slight tumor staining was observed by angiography of the left internal carotid artery but not the left external carotid artery. The patient was preoperatively diagnosed as having meningioma and underwent gross tumor resection via the basal interhemispheric approach. The tumor was strongly positive for S-100 protein and negative for epithelial membrane antigen and CD57 by immunostaining. The tumor was positive for both Schwann/2E and Sox10, which aided in the differential diagnosis between OGSs and olfactory ensheathing cell (OEC) tumors, and the definitive diagnosis was OGS. The assessment of immunoreactivities for Schwann/2E and Sox10 might be necessary to differentiate CD57-negative Schwannomas from OEC tumors.

Why are olfactory ensheathing cell tumors so rare?

The glial cells of the primary olfactory nervous system, olfactory ensheathing cells (OECs), are unusual in that they rarely form tumors. Only 11 cases, all of which were benign, have been reported to date. In fact, the existence of OEC tumors has been debated as the tumors closely resemble schwannomas (Schwann cell tumors), and there is no definite method for distinguishing the two tumor types. OEC transplantation is a promising therapeutic approach for nervous system injuries, and the fact that OECs are not prone to tumorigenesis is therefore vital. However, why OECs are so resistant to neoplastic transformation remains unknown. The primary olfactory nervous system is a highly dynamic region which continuously undergoes regeneration and neurogenesis throughout life. OECs have key roles in this process, providing structural and neurotrophic support as well as phagocytosing the axonal debris resulting from turnover of neurons. The olfactory mucosa and underlying tissue is also frequently exposed to infectious agents, and OECs have key innate immune roles preventing microbes from invading the central nervous system. It is possible that the unique biological functions of OECs, as well as the dynamic nature of the primary olfactory nervous system, relate to the low incidence of OEC tumors. Here, we summarize the known case reports of OEC tumors, discuss the difficulties of correctly diagnosing them, and examine the possible reasons for their rare incidence. Understanding why OECs rarely form tumors may open avenues for new strategies to combat tumorigenesis in other regions of the nervous system.

Subfrontal Schwannoma: Case Report and Review of Literature

BACKGROUND

Although attributing the origin of schwannomas from the olfactory nerve is nearly impossible, if they do not have Schwann cells, intracranial supratentorial schwannomas are mainly located in the anterior skull base.

CASE DESCRIPTION

We present the case of a 46-year-old female who presented with right tinnitus, dizziness, and bifrontal headache, progressive, starting 2 years before. Imaging studies revealed an incidentally neoplastic, extraaxial, homogeneously appearing tumor on the right anterior skull base. The patient underwent surgical treatment with total resection of the tumor by a bicoronal approach. The histopathologic study reported schwannoma.

CONCLUSION

We describe this case in detail and discuss the likely origin of this tumor, with a concomitant literature review.

Globose, cystic olfactory ensheathing cell tumor: A case report and literature review

Olfactory ensheathing cell tumor (OECT) is one of the most rare intracranial, extra-axial tumors located in the anterior cranial fossa. The present study reports a case of a 34-year-old female patient who presented with a history of hyposmia for 1 year, as well as a gradual dizziness and emotional lability for 2 months. Magnetic resonance imaging of the brain revealed a globose, well-defined cystic mass at the midline of the anterior cranial fossa, which was confirmed as an OECT by histology and was completely resected by bifrontal craniotomy. According to the immunostaining results, the tumor was positive for vimentin and S100 protein, and negative for epithelial membrane antigen, glial fibrillary acidic protein and cluster of differentiation 57 (also known as Leu-7). The presentation, imaging findings, histopathological examination and histogenesis of OECT are discussed in the present study, along with a literature review.

Olfactory ensheathing cell tumor: A case report and review of the literature

Olfactory ensheathing cell tumors (OECTs) are rare malignancies that occur in the anterior fossa. Little is known with regard to their clinical, radiological and immunohistochemical characteristics. The current study reports the case of a 20-year-old male with an OECT, who presented with a severe headache and a generalized convulsion. Cranial magnetic resonance imaging revealed heterogeneous enhancement of the tumor in the left anterior fossa. Complete removal of the tumor via a left frontal craniotomy was conducted, which relieved the patient's headache; however, this resulted in left-sided anosmia that remained during the two-month follow-up. The tumor was immunopositive for vimentin and S-100, and immunonegative for epithelial membrane antigen and Leu-7. The clinical data, imaging features, intraoperative findings and immunohistochemical characteristics of an additional seven cases reported in the literature are also reviewed and analyzed, providing important clinical information for the pre-operative diagnosis and intraoperative removal of OECTs.

Olfactory-ensheathing cell transplantation for peripheral nerve repair: update on recent developments

A number of important advances have been made using transplantation of olfactory-ensheathing cells (OECs) to provide therapeutic effects with regard to peripheral nerve repair. In vivo studies have focused on transplanting OECs to stimulate axonal regeneration and sprouting, increase remyelination, confer neuroprotection, enhance neovascularization and replace lost cells. OECs support axonal regeneration and remyelination with appropriate formation of axonal nodes of Ranvier with improvement of nerve conduction velocity. Current work using gene profiling and proteomics is identifying potential therapeutic differences between OECs harvested from nasal mucosa and the olfactory bulb and genes that OECs express that may be conducive to neural repair. OECs derived from nasal mucosa are of clinical interest since the cells could potentially be harvested from a patient and used for autotransplantation. Various nerve scaffolds and materials have been used for nerve repair and recent studies have examined OECs in combination with various supportive materials, including nanoparticles and scaffolds for peripheral nerve substance defects. This review will discuss the use of OECs in nerve repair and nerve defect injuries with specific emphasis on differences between OECs derived from the olfactory bulb and the olfactory mucosa.

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.