Arachnoid Membrane Research Articles

Systematic Review of Surgical Management of Spinal Intradural Arachnoid Cysts

Spinal intradural arachnoid cysts (SIACs) are rare pathological lesions that can arise via outpouchings of the arachnoid layer in the spinal canal that can result in neurological deficits. We performed a systematic literature review regarding the current surgical techniques used in the management of SIACs and discussed the prevailing hypotheses surrounding the etiology of SIACs. A systematic search of the literature was performed in December 2020 using EMBASE and MEDLINE for reports regarding the surgical management of SIACs. Data were collected regarding the demographics of the patients, classification system used, presence or absence of syrinxes, preoperative imaging modality, surgical approach and extent of resection, and postoperative outcomes and follow-up. Our search yielded 19 reports for inclusion in the present study. The 19 studies included a total of 414 cases, with an overall male/female ratio of 0.93:1. The most common site for the SIACs was the thoracic spinal cord at 77.5%. The symptoms were very similar across the 19 studies. Of the 19 studies, 15 had used resection to manage the SIACs, 10 had used fenestration or marsupialization, and 4 had used cystoarachnoid or cystoperitoneal shunts. SIACs are rare and debilitating spinal pathological lesions, with the etiology of primary SIACs still not fully elucidated. Multiple surgical approaches have been effective, with the optimal operative strategy largely dependent on the individual patient and cyst factors on a case-by-case basis.

Outcomes of Preserving the Hypertrophic Arachnoid Membrane in the Brain-meningioma Interface: Long-term Follow-up.

Abnormal hypertrophic arachnoid membranes are often observed in the brain–meningioma interface during microsurgery. They contain fibrosis and tumor cell clusters; however, preservation of the membranes does not always cause recurrence from the brain surface, and the optimal treatments in the interface remain unclear. We investigated the incidence of recurrence on the brain surface following extra-arachnoid dissection with an approach emphasizing preservation of the arachnoid membranes in meningiomas of World Health Organization (WHO) Grade I. The features of dissection cleavages in the interface were prospectively recorded at surgery. The patients were followed up with MR imaging regularly. In total, 111 patients were included. The median follow-up time was 97.0 (interquartile range [IQR] 70.0–124.0) months. The cleavages in the interface were classified into three subgroups: the Extra-H group (n = 56) with extra-arachnoid resection and preservation of hypertrophic arachnoid membranes, the Extra-N group (n = 39) with extra-arachnoid resection having normal membranes, and the Subpial resection group (n = 16). Tumors recurred in 13 (11.7%) patients at both the brain and dura mater (n = 1) or at the dura mater alone (n = 12). The median recurrence-free survival (RFS) of all recurrences was significantly related to the Simpson grades (P <0.01). For brain surface recurrence, the median RFS was not related to the subgroups. The Karnofsky Performance Scores (KPSs) significantly improved in the patients except for the Subpial group at 3 months after surgery. This study revealed that hypertrophic arachnoid membranes preserved on the brain surface rarely caused recurrence from the brain in WHO Grade I meningiomas after a long-term follow-up.

A novel SMARCA2-CREM fusion: expanding the molecular spectrum of intracranial mesenchymal tumors beyond the FET genes

A novel histomolecular tumor of the central nervous system, the “intracranial mesenchymal tumor (IMT), FET-CREB fusion-positive” has recently been identified in the literature and will be added to the 2021 World Health Organization Classification of Tumors of the Central Nervous System. However, our latest study using DNA-methylation analyses has revealed that intracranial FET-CREB fused tumors do not represent a single molecular tumor entity. Among them, the main subgroup presented classical features of angiomatoid fibrous histiocytoma, having ultrastructural features of arachnoidal cells, for. Another tumor type with clear cell component and histopathological signs of aggressivity clustered in close vicinity with clear cell sarcoma of soft tissue. Herein, we report one case of IMT with a novel SMARCA2-CREM fusion which has until now never been described in soft tissue or the central nervous system. We compare its clinical, histopathological, immunophenotypic, genetic and epigenetic features with those previously described in IMT, FET-CREB fusion-positive. Interestingly, the current case did not cluster with IMT, FET-CREB fusion-positive but rather presented histopathological (clear cell morphology with signs of malignancy), clinical (with a dismal course with several recurrences, metastases and finally the patient’s death), genetic (fusion implicating the CREM gene), and epigenetic (DNA-methylation profiling) similarities with our previously reported clear cell sarcoma-like tumor of the central nervous system. Our results added data suggesting that different clinical and histomolecular tumor subtypes or grades seem to be included within the terminology “IMT, FET-CREB fusion-positive”, and that further series of cases are needed to better characterize them.

Arachnoid Membranes: Crawling Back into Radiologic Consciousness.

The arachnoid membranes are projections of connective tissue in the subarachnoid space that connect the arachnoid mater to the pia mater. These are underappreciated and largely unrecognized by most neuroradiologists despite being found to be increasingly important in the pathogenesis, imaging, and treatment of communicating hydrocephalus. This review aims to provide neuroradiologists with an overview of the history, embryology, histology, anatomy, and normal imaging appearance of these membranes, as well as some examples of their clinical importance.

External Neurolysis in Microvascular Decompression for Magnetic Resonance Imaging–Negative Idiopathic Trigeminal Neuralgia

Internal neurolysis has been proposed as an alternative to microvascular decompression in patients with idiopathic trigeminal neuralgia (TN) in whom neurovascular compression is not confirmed by magnetic resonance imaging (MRI). External neurolysis, which straightens and realigns the trigeminal nerve root axis by dissecting the arachnoid membranes around the nerve, was reported 20 years ago in the context of so-called negative exploration when MRI did not confirm the absence of the offending vessel, but is not currently used. External neurolysis was performed in 4 patients with idiopathic TN with typical evoked neuralgic pain despite the absence of suspected offending vessels on MRI. The surgical findings that caused TN were summarized and the outcomes were evaluated using the Barrow Neurological Institute Pain Intensity Scale (BNI-PS). Tethering and distortion of the nerve root by surrounding arachnoid membranes were commonly found. All 4 patients showed complete pain relief immediately after surgery. During the follow-up period of 26.5 ± 16.92 months (±standard deviation), 3 of 4 patients had no pain (score I, BNI-PS). One patient received a score of IIIa on the BNI-PS assessment. There was no instance of recurrence or side effects associated with the surgery. Idiopathic TN can be induced by individual variation of the surrounding inner arachnoid membranes supporting the trigeminal nerve root, and the condition cannot be identified by MRI. Intradural external neurolysis may be considered an effective treatment for MRI-negative idiopathic TN.

Histopathologic features of nasal glial heterotopia (nasal glioma).

Nasal glioneuronal heterotopia (NGH) is an uncommon developmental abnormality of the nasal cavity or paranasal soft tissue. Few detailed histologic studies of NGH exist, and molecular analyses have not been performed to date. We describe six cases of pediatric NGH and two representative encephaloceles encountered in our practice over the past 20years. Two clinically distinct patient groups were noted, those with 1) intranasal nasal cavity mass (n = 3), or 2) extranasal cutaneous mass on the nose (n = 3, 1 on nasal apex, 2 on nasal bridge). Intranasal cases presented within the first week of life, whereas the extranasal NGH presented at ages of 4, 7, and 8months. Resection was curative in 5/6 cases, with a single case showing local recurrence. Histologic examination showed a predominantly glial cell composition, with nests of GFAP-immunoreactive neuropil containing large, often multinucleated astrocytes. Neurons, although difficult to identify on H&E-stains, were readily observed in all cases by NeuN-immunostain. At least focal leptomeninges were noted in 2/3 intranasal and 1/3 extranasal NGHs on routine histology, SSTR2A immunohistochemistry further confirmed leptomeninges/ arachnoid cells in 4/6 cases. 1 of 4 NGH (extranasal) cases showed copy number variations in chromosome 16, 17 and 19, which were also present in 1/2 encephalocele cases. The full significance of these alterations remains unknown. We find evidence of histologic overlap between NGH and encephalocele, and, for the first time, report molecular alterations shared between the two entities, suggesting that these conditions may represent spectrum of the same histopathologic entity.

Ablating the Transporter Sodium-Dependent Dicarboxylate Transporter 3 Prevents Leukodystrophy in Canavan Disease Mice.

Canavan disease is caused by ASPA mutations that diminish brain aspartoacylase activity, and it is characterized by excessive brain storage of the aspartoacylase substrate, N-acetyl-l-aspartate (NAA), and by astroglial and intramyelinic vacuolation. Astroglia and the arachnoid mater express sodium-dependent dicarboxylate transporter (NaDC3), encoded by SLC13A3, a sodium-coupled transporter for NAA and other dicarboxylates. Constitutive Slc13a3 deletion in aspartoacylase-deficient Canavan disease mice prevents brain NAA overaccumulation, ataxia, and brain vacuolation. ANN NEUROL 2021;90:845-850.

P06.07 Germline mutation of SMARCE1 gene in a family with spinal meningiomas

Abstract BACKGROUND Meningioma is the most common benign primary intracranial tumor, arising from arachnoid cells of the meninges, but in 20% of cases displays aggressive behavior. Meningiomas are mainly sporadic and the familial forms are very rare. Meningioma account for a small subset (1–4%) of all pediatric brain tumors and may be associated with hereditary tumor predisposition syndrome caused by germline mutations of NF2, SMARCB1, SUFU, and SMARCE1 genes. MATERIAL AND METHODS We present a case of a 16-year-old girl with spinal clear cell meningiomas (CCMs) WHO II with a second spinal lesion identified during the follow-up. Considering the multiple lesions, we performed Whole Exome Sequencing (WES) on DNA from peripheral blood to search for an underlying CCMs tumor predisposition syndrome (#607174). RESULTS We identified a heterozygous frameshift variant c.439delA (p.Ser147fs) in SMARCE1, chromatin remodelling factor that acts as a tumor suppressor gene. Meningioma analysis by Sanger sequencing showed a loss of heterozygosity (LOH) of the wild-type allele. We identified the c.439delA in the constitutional DNA of the father and the sister but not in the mother. At the moment, the father is asymptomatic and the 14 years old sister showed two spinal lesions (meningiomas likely) at the first MRI. CONCLUSION We report a family study of hereditary tumor predisposition syndrome to CCMs with SMARCE1 mutation in which are present two asymptomatic carriers with different ages and gender. The asymptomatic carriers will undergo neurological examination and MRI of the brain and spine, according to a screening protocol. The incomplete penetrance phenomenon is known in SMARCE1-related families with CCMs and it is probably due to the interaction of SMARCE1 with yet unidentified genes.

Arachnoid membrane as a source of sphingosine-1-phosphate that regulates mouse middle cerebral artery tone

Growing evidence indicates that perivascular tissue is critical to modulate vessel function. We hypothesized that the arachnoid membrane surrounding middle cerebral artery (MCA) regulates its function via sphingosine-1-phosphate (S1P)-induced vasoconstriction. The MCA from 3- to 9-month-old male and female wild-type (Oncine France 1 and C57BL/6) mice and sphingosine kinase 2 knockout (SphK2-/-) mice in the C57BL/6 background was mounted in pressure myographs with and without arachnoid membrane. Raman microspectroscopy and imaging were used for in situ detection of S1P. The presence of arachnoid tissue was associated with reduced external and lumen MCA diameters, and with an increase in basal tone regardless of sex and strain background. Strong S1P-positive signals were detected in the arachnoid surrounding the MCA wall in both mice models, as well as in a human post-mortem specimen. Selective S1P receptor 3 antagonist TY 52156 markedly reduced both MCA vasoconstriction induced by exogenous S1P and arachnoid-dependent basal tone increase. Compared to 3-month-old mice, the arachnoid-mediated contractile influence persisted in 9-month-old mice despite a decline in arachnoid S1P deposits. Genetic deletion of SphK2 decreased arachnoid S1P content and vasoconstriction. This is the first experimental evidence that arachnoid membrane regulates the MCA tone mediated by S1P.

A PROSPECTIVE HISTOPATHOLOGICAL STUDY OF MENINGIOMAS IN A TERTIARY CARE CENTRE OF VIJAYAWADA

Background: Meningiomas are neoplasms arising from the arachnoidal cap cells in the meningeal coverings of the spinal cord and brain. These are the most common benign intracranial tumours and account for about 13-26% of all primary brain neoplasms. These are generally benign neoplasms of adults most often seen in middle age, but about 10% are atypical or malignant. These neoplasms are graded by WHO as Grade I , II and III . Benign meningiomas can be cured by surgical resection where as higher grade meningiomas require radiotherapy after surgical resection as these higher grade meningiomas have greater recurrence and aggressive behavior. Aims and Objectives: To study the variants and histopathological spectrum of meningioma and prognosis of variants. Material &amp; Methods: The present study is a prospective study conducted in the department of Pathology, Siddhartha medical college from June 2019-May 2020. During this study, 16 cases of meningiomas were diagnosed and reviewed. Result:In our study of 16 cases females were 62.5%. The most common age group is 41-60 yrs (68.75%). Most common variant was noted to be transitional meningioma followed by meningothelial meningioma. Out of the 16 cases, grade I were 81.25%. Conclusion: Meningiomas account for 28-30% of primary central nervous system tumors and unveil a heterogeneous histopathology. The histological appearance of meningioma determines the grading for the management of the various subtypes and also associated with patient's prognosis. Hence a continuous revision of histopathological classication systems is required to improve the diagnostic accuracy. Benign meningiomas are the most common type. From our study, we conclude that transitional meningioma is the most common benign variant.

Warning with chronic subdural hematomas in the elderly

Chronic subdural hematoma (cSDH) is a disorder in which blood collects between the dura and arachnoid mater of meninges around the brain. It's more common among the elderly and usually triggered by a head injury. We report a case of a 78-year-old male patient who had previously been diagnosed with a left hemisphere subdural hematoma for no apparent reason with a history of hypertension. Two days before hospitalizing, he had a symptom of weakness in the right extremities. Non-contrast CT of head reveals a crescent-shaped, heterodense lesion over the lateral aspect of the left hemisphere measuring 11x5x1 cm with mass effect to the adjacent brain parenchyma. Burr hole drainage was performed for the patient. His symptoms improved after the surgery.

Preserved arachnoid membrane acts as a predictor of postoperative visual improvement in clinoidal meningioma

ObjectivesImprovement of patient visual outcome is very important in the treatment of clinoidal meningioma (CLM). The purpose of this study is to determine the association between arachnoid preservation and visual outcome. PatientsFifteen patients with CLMs that caused visual impairment underwent surgery in our hospital. The patients included 4 men and 11 women, and the mean age was 53.3 years. MethodsThe clinical findings of these patients were retrospectively reviewed. We divided the patients into two groups based on the presence or absence of the arachnoid membrane. Group 1 comprised cases in which arachnoid preservation was intraoperatively confirmed. Group 2 comprised cases in which the arachnoid membrane was not preserved. The Landolt C chart was used to evaluate visual acuity, and dynamic visual field tests using Goldmann perimetry were used to evaluate the visual field. Results were compared before and after surgery. ResultsThe visual acuity of the ipsilateral eye was significantly improved in Group 1 (p = 0.038). There were no other significant differences between the two groups in terms of tumor volume, patient age, and symptom duration. ConclusionsPatients in which arachnoid preservation could be intraoperatively confirmed had good improvement in visual acuity. Further research with an increased number of cases is needed to confirm these findings.

Suboccipital midline approach with C1 laminectomy and C2 partial laminectomy for anterolateral foramen magnum meningioma: A case report

Introduction: Foramen magnum meningiomas (FMMs) arise from meningothelial cells of arachnoid layer in the craniospinal junction. FMMs are rare and comprise only 1.8 to 3.2% of all meningiomas. Patients with FMMs generally have vague symptoms and are often misdiagnosed. Surgical management of FMMs poses a challenge because foramen magnum is a highly complex territory of the skull base and contains many important and vital structures. Up until this date, the surgical approaches for FMMs that arise anterolaterally remain varied. We aimed to present a case of anterolateral FMM that was successfully managed through posterior suboccipital midline approach.Case presentation: A 49-year-old female presented with chief complaint of tetra paresis for the past 4 months. Initially, she was experiencing tingling and numbness on her right neck radiating to her right hand. Her symptoms were worsened, radiating to all of her four extremities along with progressive motor weakness that made her unable to walk. Whole spine MRI was performed and anterior meningioma extending to the right side at the level of foramen magnum was found. The posterior suboccipital midline approach with C1 laminectomy and C2 partial superior laminectomy was performed. The patient made a good recovery immediately after the surgery and there was no recurrence of her symptoms during 4 months follow-up.Conclusion: Surgical approaches for FMM remain varied according to several studies. However, the surgical strategy should be patient-tailored to achieve the maximal resection and prevent morbidity. As for our case, posterior suboccipital midline approach is safe and feasible surgical procedure to treat anterolateral FMM.Keywords: foramen magnum, meningioma, suboccipital midline approach

Suturing of the Arachnoid Membrane for Reconstruction of the Cisterna Magna: Technical Considerations

Postoperative cerebrospinal fluid (CSF) fistula following cranial or spinal surgery is associated with increased morbidity and mortality. To prevent CSF fistulas, various techniques have been described. Here, we describe the arachnoid membrane continuous-running suture technique in cisterna magna reconstruction for preventing postoperative CSF leakage. After craniotomy and dural opening, the incision of the arachnoid of the cisterna magna was performed using a diamond blade. To prevent the arachnoid from drying out and shrinking during surgery, it was periodically irrigated with warm saline solution. Posterior fossa surgery was performed. When closing the membranes, the arachnoid membrane was closed with the running-suture technique. After the first surgical knot was made in the cranial end of the arachnoid opening, continuous suturing with a 2-mm distance between the stitches was performed without stretching them. After every 3 stitches, the free end of the thread was pulled gently along the suturing axis, and the edges of the arachnoid were closed. After the arachnoid edges were approximated, the surgical knot was tied. Watertight closure was checked byperforming the Valsalva maneuver at the end of the surgery. No CSF leakages were observed after surgery. Arachnoid membrane suturing seems to be safe and effective in preventing postoperative CSF leakage and CSF-related complications. Using continuous running suturing alone, without any sealant, might beeffective in cases with untraumatized arachnoid membrane.

Dural Stimulation and Periorbital von Frey Testing in Mice As a Preclinical Model of Headache.

The cranial meninges, comprised of the dura mater, arachnoid, and pia mater, are thought to primarily serve structural functions for the nervous system. For example, they protect the brain from the skull and anchor/organize the vascular and neuronal supply of the cortex. However, the meninges are also implicated in nervous system disorders such as migraine, where the pain experienced during a migraine is attributed to local sterile inflammation and subsequent activation of local nociceptive afferents. Of the layers in the meninges, the dura mater is of particular interest in the pathophysiology of migraines. It is highly vascularized, harbors local nociceptive neurons, and is home to a diverse array of resident cells such as immune cells. Subtle changes in the local meningeal microenvironment may lead to activation and sensitization of dural perivascular nociceptors, thus leading to migraine pain. Studies have sought to address how dural afferents become activated/sensitized by using either in vivo electrophysiology, imaging techniques, or behavioral models, but these commonly require very invasive surgeries. This protocol presents a method for comparatively non-invasive application of compounds on the dura mater in mice and a suitable method for measuring headache-like tactile sensitivity using periorbital von Frey testing following dural stimulation. This method maintains the integrity of the dura and skull and reduces confounding effects from invasive techniques by injecting substances through a 0.65 mm modified cannula at the junction of unfused sagittal and lambdoid sutures. This preclinical model will allow researchers to investigate a wide range of dural stimuli and their role in the pathological progression of migraine, such as nociceptor activation, immune cell activation, vascular changes, and pain behaviors, all while maintaining injury-free conditions to the skull and meninges.

P-OT023. Intracranial subdural empyema mimicking acute on chronic subdural hematoma: a case report

Introduction. Intracranial subdural empyema is a rare localized intracranial infection that forms between dura and arachnoid membrane of the meninges. Its unspecific clinical presentations as well as neuroimaging findings that might resemble subdural hematoma make the definitive diagnosis of subdural empyema difficult. This report aims to highlight the importance of making a differential diagnosis of subdural empyema in a suspected case of subdural hematoma. Results. A 71 years old male presented with acute mild to moderate intermittent headache that was followed by sudden difficulty in word findings and right limbs weakness. No history of fever, trauma, seizure, or prior history of ear, nose, throat, tooth infections, and intracranial surgical procedure. Increased white blood cells count was not found despite the increased neutrophil to lymphocyte ratio as well as C-reactive protein. Non-contrast head CT-scan showed crescentic hyperdense lesion within a wider hypodense lesion in the left frontotemporoparietal region, characterizing acute on chronic subdural hematoma. During burr hole drainage, pus was found, consistent with subdural empyema. An intralesion antibiotic treatment was given after complete removal of the pus. Conclusion. Intracranial subdural hematoma and subdural empyema with the involvement of neurological deficits are emergency conditions. However, it is difficult to differentiate these two conditions even after the examinations of clinical, laboratory, and neuroimaging with non- contrast head CT-scan, particularly without the triad of subdural empyema: fever, headache, vomiting. Our case showed that even without noticeable port d’entry, intracranial subdural empyema could be formed.

Two distinct case reports with foamy cell and differential diagnosis: Xanthomatous meningioma and review of literature

Meningiomas are the most common primary intracranial tumor thought to derived from arachnoidal cap cells in the meningeal coverings of the spinal cord and brain. The current WHO classification, published in 2016, includes nine different subtypes of grade 1 meningiomas, three different subtypes of grade 2 meningiomas, and three different subtypes of grade 3 meningiomas. Metaplastic meningioma is a rare variant which shows focal or diffuse mesenchymal tissue component. Xanthomatous meningioma which has foamy cell changes is a quite rare variant of metaplastic meningioma. Two patients, 54 and 59 years old, who applied to our clinic with similar symptoms, were operated for meningioma. Histopathological examination of their biopsy showed that neoplastic cells had oval-round nuclei and eosinophilic cytoplasm. In xanthomatous meningioma, some neoplastic cells had clear vacuolated cytoplasm (foamy cells). In microscopic examination of resection material in one of these patients, cells in some areas of the tumor had clear vacuolated cytoplasm (foamy cells). These neoplastic cells were scattered among other meningothelial cells and they were positive for EMA. To the best of our knowledge, until today there have been only 14 reported xanthomatous meningioma cases in English literature. Here, we aimed to discuss the pathogenesis and differential diagnosis of xanthomatous meningioma in two different cases

Spinal arachnoid web—a distinct entity of focal arachnopathy with favorable long-term outcome after surgical resection: analysis of a multicenter patient population

BACKGROUND CONTEXTSpinal arachnoid web (SAW) is a rare condition characterized by focal thickening of the arachnoid membrane causing displacement and compression of the spinal cord with progressive symptoms and neurological deficits. Recent reports and clinical experience suggest that SAW is a distinct entity with specific radiological findings and treatment strategies distinguishable from other arachnopathies and potential differential diagnoses. PURPOSETo better define the diagnostic and clinical features, treatment options and outcomes of surgically treated SAW. STUDY DESIGNMulticentric retrospective cohort study. PATIENT SAMPLETwelve cases of SAW surgically treated at three different centers. OUTCOME MEASURESSelf-reported and neurological outcome measurements (pain, sensory-motor deficits, vegetative dysfunctions) were assessed at follow-up timepoints. METHODSRetrospective review of prospectively collected data on all patients surgically treated for SAW from three participating neurosurgical centers between 2014 and 2020. Clinicopathological data, including neurological presentation, radiological and histological findings and outcome data were analyzed. RESULTSTwelve radiologically and surgically confirmed cases of SAW were analyzed. Mean patient age was 54.7 [±12.7], 67% were male. All SAWs were located in the posterior thoracic dural sac. On magnetic resonance imaging (MRI), the “scalpel sign” - a characteristic focal dorsal indentation of the spinal cord resembling a scalpel blade - was identified in all patients. A focal intramedullary syrinx was present in 83%. Preoperative clinical symptoms included signs of myelopathy, pain, weakness and sensory loss, most commonly affecting the trunk/upper back or lower extremities. Laminectomy or laminoplasty with intradural excision of the SAW was the surgical treatment of choice in all cases. Intraoperative ultrasound was valuable to visualize the cerebrospinal fluid (CSF) flow obstruction, confirm the SAW location before dura incision and to control adequacy of resection. After surgery, sensory loss and weakness in particular showed significant improvement. CONCLUSIONSThe present study comprises the largest series of surgically treated SAW, underscoring the unique clinical, radiographic, histopathological, and surgical findings. We want to emphasize SAW being a distinct entity of spinal arachnopathy with a favorable long-term outcome if diagnosed correctly and treated surgically. Intraoperative ultrasound aids visualizing the SAW before dural incision, as well as verifying restored CSF flow after resection.

PRIMARY EXTRACRANIAL MENINGIOMA OF THE MANDIBLE: A CASE REPORT AND LITERATURE REVIEW OF THIS RARE PRESENTATION

Meningiomas are common benign neoplasms developing within the central nervous system and arise from the meningothelial cells. Extracranial (ectopic) meningiomas are rare and may represent an extracranial extension of an intracranial meningioma or distant metastasis from a primary intracranial meningioma, or they may originate from arachnoid cells in the sheaths of the cranial nerves that are exiting the skull through the foramina or sutures. Ectopic meningiomas can also arise as true primary extracranial meningiomas originating from ectopic arachnoid lining cells or multipotential mesenchymal cells. Primary extracranial meningiomas occurring in the jaws are extremely rare, with only 11 reported cases (2 cases in the maxilla and 9 cases in the mandible) in the literature. The infrequent occurrence of this entity presenting in this unusual location of the jaws often poses a diagnostic challenge to the oral pathologist, resulting in misdiagnosis. We present the 10th mandibular case of extracranial meningioma involving the right side of the mandible in a 56-year-old female patient. The clinical and radiographic presentation, histopathologic features, and histopathologic differential and immunohistochemical findings of this case are presented. The proposed pathogenesis, treatment options, and prognosis are also discussed along with a review of the literature.

Clinicopathological Study of Meningioma in a Sample of Iraqi Patients in Baghdad District

BACKGROUND: Meningiomas are tumors that arise from the meningothelial cells that line the arachnoidal cell layer of meningeal coverings in the brain and the spinal cord. They constitute one of the most common types of primary intracranial tumors. OBJECT: To evaluate a number of cases of meningiomas that have undergone surgical procedures in the past three years and to record the frequency of various histopathological variants and tumor grades according to 2016 World Health Organization (WHO) classification and their correlation with clinical parameters such as age, gender and tumor location. METHODS: A retrospective case series study of 57 patients with meningioma surgically operated in the neurosurgery department of Ghazi Al-hariri hospital in Baghdad, Iraq, between January 2018 and December 2020. The epidemiology, clinical manifestations, tumor sites and histopathological variants were studied. RESULTS: The mean age of patients in this study was 48.4 ± 12.5 years, with a male-to-female ratio of 1:4. Intracranial meningiomas represented 49/57 cases (86%). The most frequent clinical presentations for intracranial meningiomas were headache (61.2%), blurred vision (36.7%) and seizures (21.4%). WHO grade 1 meningiomas represented the vast majority of tumors in the present study with a total of 55/57 cases (96.5%). The most common histopathological variant was the meningothelial variant in 41/57 cases (71%). CONCLUSION: Meningioma is a common primary intracranial tumor in adults. Females are more prone to developing this tumor than males. Most cases of meningioma behave as benign neoplasms; however, a considerable number presented as recurrent tumors, which implies that further research is required.