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Clear cell meningiomas (CCM) are an uncommon meningioma subtype marked by aggressive growth and high rates of recurrence despite initial resection. The present study evaluates the adjuvant benefit of stereotactic radiosurgery (SRS) for residual or recurrent tumors. After review of our prospectively maintained database, we identified 6 patients (3 female) with histologically confirmed Grade 2 CCMs. The median age of the patients at the time of SRS was 45 years. Five patients had undergone prior gross total surgical resection and 1 patient had subtotal resection before SRS. The median SRS treatment volume was 4.7 cc and the median radiosurgical margin dose was 13 Gy (range: 10–15 Gy). The median follow-up time was 35.5 months (range 6–168 months). Three patients achieved tumor control after the first SRS procedure. Three patients experienced tumor progression at 4, 22, and 32 months after initial SRS. Tumor control was obtained in 2 of these patients after additional SRS. One patient with multiple SRS procedures had suspected adverse radiation effect that was successfully treated with corticosteroids followed by bevacizumab. Tumor control was maintained in 5 of 6 patients after one or more SRS procedures. SRS should be considered for early intervention after surgical resection of CCM. To maximize the tumor control rate, patients with diagnosed CCM should be treated more generously and higher margin dose should be prescribed. Patients with CCM should be counselled that more than one SRS may be necessary to provide sustained tumor control. [ABSTRACT FROM AUTHOR]

Simple Summary: This study offers a comprehensive review of the current basic science and clinical literature concerning the diagnosis and treatment of spinal meningiomas in conjunction with illustrative case studies to emphasize up-to-date knowledge on molecular genetics, surgical resection, and alternative therapies. Spinal meningiomas are the most common intradural, extramedullary tumor in adults, yet the least common entity when accounting for all meningiomas spanning the neuraxis. While traditionally considered a benign recapitulation of their intracranial counterpart, a paucity of knowledge exists regarding the differences between meningiomas arising from these two anatomic compartments in terms of histopathologic subtypes, molecular tumor biology, surgical principles, long-term functional outcomes, and recurrence rates. To date, advancements at the bench have largely been made for intracranial meningiomas, including the discovery of novel gene targets, DNA methylation profiles, integrated diagnoses, and alternative systemic therapies, with few exceptions reserved for spinal pathology. Likewise, evolving clinical research offers significant updates to our understanding of guiding surgical principles, intraoperative technology, and perioperative patient management for intracranial meningiomas. Nonetheless, spinal meningiomas are predominantly relegated to studies considering non-specific intradural extramedullary spinal tumors of all histopathologic types. The aim of this review is to comprehensively report updates in both basic science and clinical research regarding intraspinal meningiomas and to provide illustrative case examples thereof, thereby lending a better understanding of this heterogenous class of central nervous system tumors. [ABSTRACT FROM AUTHOR]

Abstract Background Meningioma is the second most common intradural extramedullary tumor, following schwannoma. Meningioma is primarily categorized as benign World Health Organization grade 1, but clear cell meningioma is grade 2 of the intermediate malignant category. Clear cell meningiomas are rare, accounting for less than 1% of all meningioma tumors. There is no previous report of multiple intraspinal clear cell meningiomas without dural attachment. Case presentation A 27-year-old Asian male patient presented with lower right extremity pain, and had undergone tumor resection for intracranial clear cell meningioma 7 years previously, with re-resection and radiotherapy for local tumor recurrence at our hospital’s department of neurosurgery being carried out 4 years previously. No recurrence was observed since then. Preoperative lumbar magnetic resonance imaging showed two tumors at the L1 and L4 levels, both mimicking schwannoma with well-defined margins, no dural tail sign and homogeneous internal contrast. Intraoperative findings on tumor resection showed two tumors contiguous with the right L2 and L5 roots, which were not attached to the dura mater, similar to a schwannoma. After gross total resection, the postoperative pathology revealed no nuclear SMARCE1 antibody staining. The patient was diagnosed with clear cell meningioma. The patient’s postoperative course went well, with no symptoms of nerve dropout and no recurrence 2 years after surgery. In this case, both lumbar lesions were well demarcated and spherical in shape, occurring with single roots. Tumor characteristics suggested a primary rather than a metastatic lesion. Clear cell meningioma is characterized by a SMARCE1 mutation and is different from other types of meningiomas. Conclusion To the best of our knowledge, this is the first report of multiple intraspinal clear cell meningiomas without dural attachment at the lumbar spine after resection of intracranial clear cell meningioma. We speculate that the two tumors were de novo lesions on the basis of the features of the tumors, although they were detected 7 years after the resection of intracranial clear cell meningioma.

Clear cell meningioma (CCM) is an uncommon histologic subtype of meningioma classified as a WHO grade II tumor and accounting for less than 1% of all meningiomas. Demographically, younger patients are commonly affected without any remarkable gender preference. Moreover, CCM shows a unique anatomical site of involvement. It tends to occur in the cranium than the spine, whereas the basilar skull, posterior fossa and lumbar spine have been the most frequently affected area. Although most cases present as typical the mass effect by the tumor, CCM exhibits characteristic imaging and histologic patterns. Even though surgical resection is the treatment of choice, recurrence-free survival is the biggest challenge and has been attempting to improve by adjuvant therapy. There is still debate about its management, outcome and factors defining it. Herein, we aimed to summarize natural history, radiographic characteristics, histological features, treatment strategies to guide the best possible individualized care for the most favorable outcome. [ABSTRACT FROM AUTHOR]

Clear cell meningiomas (CCM) are a very rare histologic subtype of meningioma usually affecting younger patients. The reported data on spinal CCM are extremely rare. Until today, only 89 cases have been reported. Furthermore, CCM without dural attachment is even rarer since only 19 cases have been reported in English literature. In this article, we present the twentieth case of a spinal CCM without dural attachment. Our patient was a 58-year-old female who was presented with pain in her lower back and bilateral sciatica for 6 months. Magnetic resonance imaging showed an intra-dural well-demarcated lesion at L3. Via a posterior approach, total resection was possible due to the lack of dural adhesion of the tumor. Histologic diagnosis was clear cell meningioma.

Clear cell meningioma (CCM) is a rare histological variant of meningioma. It is commonly located at the cerebellopontine angle and the spine particularly around the cauda equina. Squash cytology finding of meningioma is well‐established, however there is sparse literature available on squash cytology of CCM. Here we describe a case of CCM occurring in the lumbar spine in a young woman. Initially, on squash cytology a diagnosis of a low grade glioma favouring an ependymoma was considered. Eventually histopathological examination along with immunohistochemistry helped us reach the diagnosis of a CCM. In this article we discuss the cytomorphology of CCM along with its cytological differentials and the hurdles to an accurate diagnosis. [ABSTRACT FROM AUTHOR]

Clear cell meningioma (CCM) is a rare subtype of meningioma, especially unusual as a neoplasm of the filum terminale. Clear cell meningioma seems to have a more aggressive nature and a higher risk of recurrence than WHO grade I meningiomas. A 44-year-old woman presented with lower back pain radiating to the left leg and mild weakness in the left leg. Magnetic resonance imaging (MRI) showed a well-demarcated, intradural lesion filling the spinal canal at the L3-S1 levels and compressing the cauda equina. The patient underwent laminectomy from L3 to S1. During the operation, the filum terminale was identified as a structure that was disappearing into the tumor. The filum terminale was cut and the tumor was totally removed in one piece. Pathological findings were indicative of the diagnosis of clear cell meningioma, CNS WHO G2. Postoperative magnetic resonance imaging at 6 months showed no residual mass. Total surgical excision of the CCM of the spinal cord should be chosen as the optimal treatment. In addition, radiological follow-up is equally important due to the high risk of recurrence. Our case is unusual in that the tumor's location was the filum terminale.

Meningioma is a common primary tumor of the central nervous system and one of the most encountered brain tumors. Although classic histopathologic features of meningioma are relatively common and make its diagnosis straightforward, certain variants possess unusual histologic features causing diagnostic challenges. We reported three cases of clear cell meningioma, microcytic meningioma, and angiomatous meningioma report, variants with potential deceptive morphologies, and discuss their distinguishing morphologic features.

Clear cell meningiomas (CCMs) account for only approximately 0.2% of all meningiomas and are classified as grade II tumours by the World Health Organisation. Most of the previously described intracranial CCMs are single tumour entities. Multiple intracranial CCMs are extremely rare, and due to their low incidence, information on multiple CCM remains limited; hence, researchers and practitioners also have a limited understanding of its aetiology, clinical manifestations, and treatment options. Herein, we report a case of sporadic multiple intracranial CCM in a child that presented with a 3-month history of gait instability and mild dysphagia. Brain magnetic resonance imaging showed one lesion in the right frontoparietal lobe and another giant lesion on the ventral side of the brainstem, extending to the middle fossa. The lesions were completely resected in two stages. Postoperative histopathological examination confirmed CCM. The patient was followed up for 2 years without recurrence. To the best of our knowledge this is the first reported case of paediatric sporadic multiple intracranial CCM. In addition, we reviewed the relevant literature to discuss the pathogenesis, imaging findings, and treatment methods of this rare disease. [ABSTRACT FROM AUTHOR]

BackgroundClear cell meningioma (CCM) is a rare subtype of meningioma, accounting for approximately 0.2% of all meningiomas. The present study aimed to analyze the epidemiology and outcome of CCMs using the Surveillance, Epidemiology, and End Results (SEER) database.MethodsPatients diagnosed with central nervous system CCM between 2004 and 2016 were identified from the SEER database. Descriptive analyses were performed to evaluate the distribution of patients and tumor-related characteristics. The survival analysis was performed using Kaplan-Meier curves. The Cox proportional hazards model was used for the univariate and multivariate analyses.ResultsThe age-adjusted incidence rate was 0.032 per 1,000,000 person-years. The median age was 52 years. Most of the CCMs were intracranial CCMs that were larger than 3 cm. The overall cumulative survival rates at 1, 3, and 5 years were 97.6, 93.2, and 86.9%, respectively. The log‐rank test and Cox proportional hazards regression analysis revealed that age at diagnosis and primary site of the tumor were independent prognostic factors.ConclusionCCM is an extremely rare entity with a favorable survival rate. CCMs usually affect patients during the fourth to fifth decades of life. Patients diagnosed at 21–60 years old and patients with spinal CCMs have a better prognosis.

Clear cell meningioma (CCM) is a rare variant of meningioma. In recent years, an association between cranial and spinal CCMs and germline loss of function mutations in the SMARCE1 gene (SWI/SNF chromatin remodeling complex subunit gene) has been discovered. We report a family with an incidental large spinal clear cell meningioma in a young adult following reflex screening for a germline loss of function pathogenic variant (PV) in the SMARCE1 gene. The index patient's mother and maternal grandfather were both also tested positive presymptomatically for SMARCE1. His mother developed intracranial and spinal meningiomas and his maternal grandfather developed a spinal CCM 4 years following a clear spinal MRI scan which required surgical excision. In this report we particularly emphasize the importance of genetic counseling and screening in siblings, parents and offspring of patients who are diagnosed with intracranial or spinal CCM in the context of SMARCE1 PVs. We recommend brain and spine Imaging screening of asymptomatic SMARCE1 PV carriers at least every 3 years, even if the baseline scan did not show any tumors. [ABSTRACT FROM AUTHOR]

Background: Clear cell meningioma (CCM) is a rare subtype of meningioma, accounting for approximately 0.2% of all meningiomas. The present study aimed to analyze the epidemiology and outcome of CCMs using the Surveillance, Epidemiology, and End Results (SEER) database. Methods: Patients diagnosed with central nervous system CCM between 2004 and 2016 were identified from the SEER database. Descriptive analyses were performed to evaluate the distribution of patients and tumor-related characteristics. The survival analysis was performed using Kaplan-Meier curves. The Cox proportional hazards model was used for the univariate and multivariate analyses. Results: The age-adjusted incidence rate was 0.032 per 1,000,000 person-years. The median age was 52 years. Most of the CCMs were intracranial CCMs that were larger than 3 cm. The overall cumulative survival rates at 1, 3, and 5 years were 97.6, 93.2, and 86.9%, respectively. The log‐rank test and Cox proportional hazards regression analysis revealed that age at diagnosis and primary site of the tumor were independent prognostic factors. Conclusion: CCM is an extremely rare entity with a favorable survival rate. CCMs usually affect patients during the fourth to fifth decades of life. Patients diagnosed at 21–60 years old and patients with spinal CCMs have a better prognosis. [ABSTRACT FROM AUTHOR]

Purpose: Clear cell meningioma (CCM) is a rare WHO grade II meningioma variant, characterized by aggressive features and a high tumor recurrence rate. In this study, we compared overall and progression-free survivals between CCMs and other WHO grade II meningiomas. Methods: A retrospective institutional database review was performed to identify all patients who underwent surgical resection of a WHO grade II meningioma between 1997 and 2019. Overall survival and progression-free survival were compared between patients with clear cell meningiomas and patients with other WHO grade II meningiomas. Multivariable Cox proportional-hazards analysis was used to identify independent predictors of tumor recurrence and survival. Results: We included a total of 214 patients in this study (43 CCMs, 171 other WHO grade II meningiomas). Patients with CCMs had significantly shorter progression-free (p = 0.001) and overall (p = 0.026) survivals than patients with other grade II meningiomas. In multivariable analysis, clear cell histology was a significant and powerful independent predictor of tumor recurrence (HR 1.93; 95% CI 1.14–3.26) when controlling for tumor location, extent of resection, and adjuvant radiation. In multivariable analysis, clear cell histology correlated with increased mortality (HR 1.96, 95% CI 0.97–3.94), though this was not statistically significant. Conclusion: This is the first study to compare overall and progression-free survivals between CCMs and other WHO grade II meningiomas. Clear cell histology predicts a higher risk of tumor recurrence and mortality than other grade II histologies. Future studies may help to understand the impact of these findings and the treatment implications. [ABSTRACT FROM AUTHOR]

Spinal clear cell meningiomas (CCMs) are rare and dural-based lesion usually affecting the younger population. We report the rare case of giant nondural-based spinal CCM mimicking schwannoma and review the literature. A literature search was performed at PubMed and Embase until January 1, 2020. A total of 19 cases of nondural-based spinal CCM was reported. The following relevant data were extracted: authors, publication year, patient and tumor characteristics, treatment, and outcome. The mean age of the presentation was 20.58 years. Twelve (63.16%) were female and seven patients (36.84%) were male. The most common location was lumbosacral region 15 (79%). Fifteen (79%) tumors had cranio-caudal dimension ≤2 vertebral level, and only four (21%) tumors had dimension ≥2 vertebral level. Gross total resection (GTR) was performed in 18 (95%) patients and subtotal resection (STR) in 1 patient. Recurrences were reported in five (26.14%) patients. Four of them showed recurrences within 6 months; earliest at 2.3 months in the patient had undergone STR. Our patient is 19-year-old male diagnosed with a lumbosacral intradural lesion. Craniocaudal dimension is ≥2 vertebral level shows the foraminal extension and vertebral scalloping. GTR is performed. Intraoperatively, the tumor has foraminal extension and shows attachment with right S1S2 nerve root. No dural attachment is found. Six-month follow-up magnetic resonance image shows no evidence of disease. Nondural-based spinal CCMs are extremely rare and should be kept as a differential diagnosis in young patients with giant intradural tumor, and whose radiological features suggesting of schwannoma. It affects young patients and usually involves more than one vertebral level. The chances of recurrences and metastasis are always high even after GTR; hence, close follow-up of the entire neuraxis is warranted. [ABSTRACT FROM AUTHOR]

Clear cell meningioma (CCM) is a rare histologic variant, accounting for only 0.2%–0.8% of all meningiomas. Given their relative infrequency, few cases have been reported. We have presented one of the largest series of patients with intracranial CCM and reported the treatments and outcomes of these patients. Patients with histologically proven CCM from 2003 to 2018 were identified for inclusion in the present study. Relevant clinical and radiographic data were obtained via retrospective review and analyzed. Kaplan-Meier and Cox proportional hazards analyses were used to compare overall and progression-free survival. A total of 35 patients had undergone surgical resection for CCM, including 18 women and 17 men, with a mean age of 59.3 years. Gross total resection was achieved in 22 patients (62.9%), and 11 patients (31.4%) had received adjuvant postoperative radiotherapy. Tumors recurred in 17 patients (48.6%), with a mean time to recurrence of 31.3 months. The mean postoperative follow-up was 66.3 months. On multivariable analysis, adjuvant radiotherapy and gross total tumor resection were both independently associated with prolonged progression-free survival (P < 0.033), although not with overall survival (P >0.274). The data from the present series of 35 patients with CCM have shown distinct contrasts to previous series, with an older mean age and a nearly 1:1 male/female ratio. Although gross total resection and adjuvant postoperative radiotherapy were both independently associated with longer progression-free survival for patients with CCM, tumor recurrence has remained a challenge in the treatment of these patients. [ABSTRACT FROM AUTHOR]

Although spinal meningiomas are uncommon in children, clear cell meningioma has been described as the most common variant of spinal meningiomas in the pediatric age group. 24 cases of pediatric spinal clear call meningioma have been reported in the literature. We report one case and review the literature regarding pediatric spinal clear cell meningioma. [ABSTRACT FROM AUTHOR]

Background Clear cell meningioma (CCM) is a rare histologic subtype of meningioma. The features of CCMs have commonly been based on intracranial cases. However, CCMs in the spinal cord are even rarer, and their natural history, management, and prognosis remain ill-defined. Methods From January 2006 to January 2018, 12 patients with spinal CCM were treated in our hospital. The clinical features, radiologic findings, diagnosis, treatment, and outcome of these patients were analyzed retrospectively. Additionally, we performed a review of the reported data on spinal CCMs. Results CCMs accounted for 2.8% of all the spinal meningiomas treated in our hospital. The most common localization of this disease was the lumbar region (7 of 12). The mean age at diagnosis was significantly younger than that of patients with spinal meningiomas (28.8 ± 13.4 years vs. 54.0 ± 14.4 years). During the follow-up period, 5 patients (41.7%) experienced tumor recurrence. Kaplan-Meier analysis showed that younger patients had a significantly shorter progression-free survival time than older patients. The review of the reported data showed that 55 cases of spinal CCMs had been reported. Nineteen patients (38.0%) had developed local recurrence, with a 5-year progression-free survival rate of 33.3%. Conclusions Spinal CCMs are extremely rare tumors with a predilection to affect younger patients and have a high recurrence rate. Although gross total resection is considered to be the optimal treatment, radiotherapy could be considered for patients who had undergone subtotal resection or for younger patients, regardless of the extent of removal. Close follow-up of the entire neuraxis for years is crucial. [ABSTRACT FROM AUTHOR]

Clear cell meningiomas (CCMs) are rare subtypes of meningiomas and usually treated by maximum safely achievable tumor resection. We here present three hereditary cases with CCMs which were confirmed by Sanger sequencing of lymphocyte DNA. Gross total resection was achieved in a 5-year-old son with a spinal CCM and a 34-year-old father with a CCM in the cerebellopontine angle (CPA). For a 14-year-old daughter with CCM in the CPA, total resection was not achieved due to its large size. Early detection by screening high-risk family with CCM is strongly recommended. [ABSTRACT FROM AUTHOR]

Clear cell meningiomas are an uncommon subtype of meningioma rarely seen in infancy. We report a case of clear cell meningioma in an 8-month-old male infant. He presented at the Lagos University Teaching Hospital, Lagos, Nigeria, in 2015 with persistent vomiting, poor feeding and failure to thrive over a four month period. Generalised hypertonia and hyperreflexia were noted on examination. Computed tomography of the brain revealed a huge largely isodense suprasellar mass with a hypodense core. The tumour, which measured 6 x 5 x 4 cm, enhanced non-uniformly with contrast injection and extended to occlude the third ventricle. The patient underwent a bifrontal craniotomy with subtotal tumour excision. Six hours postoperatively, he went into cardiac arrest and could not be resuscitated. A histological diagnosis of clear cell meningioma was made as the tumour cells were immunoreactive to epithelial membrane antigen, S100 protein and vimentin. This case of clear cell meningioma was unusual due to its early occurrence and supratentorial location.

Abstract: Clear cell meningioma (CCM) is a rare grade II histopathological subtype that usually occurs in young patients and displays high recurrence rate. Germline SMARCE1 mutations have been described in hereditary forms of this disease and more recently in small syndromic and sporadic CCM series. The diagnostic value of SMARCE1 in distinguishing between CCM and other meningioma variants has not been yet established. The aim of our study was to investigate the status of SMARCE1 in a series of CCMs and its morphological mimickers. We compared the performance of an anti‐SMARCE1 antibody and the molecular analysis of the SMARCE1 gene in a retrospective multicenter series of CCMs. All CCMs lossed SMARCE1 immunoexpression. Bi‐allelic inactivating events were found by NGS‐based sequencing in all of these cases, except for one, which was incompletely explored, but had a wild‐type sequence. We then validated the anti‐SMARCE1 antibody specificity by analyzing additional 305 pediatric and adult meningiomas of various subtypes and 15 non‐meningioma clear cell tumors by SMARCE1 immunohistochemistry. A nuclear immunostaining was preserved in all other meningioma variants, as well as non‐meningioma clear cell tumors. In conclusion, our series showed, for the first time, that SMARCE1 immunostaining is a highly sensitive biomarker for CCM, useful as a routine diagnostic biomarker. [ABSTRACT FROM AUTHOR]

We report a case of a recurrent clear cell meningioma (CCM) in the frontal lobe of the brain of a 67-year-old man. The patient developed three recurrences: at 3, 10, and 12 years after his initial surgery. Histopathology observations revealed a grade 2 CCM with positivity for vimentin and epithelial membrane antigen. Expression of E-cadherin was positive only in the primary tumour and in the first available recurrence. Fluorescence in situ hybridization analyses demonstrated 1p and 14q deletions within the last recurrence. Multiplex ligation-dependent probe amplification studies revealed a heterozygous partial NF2 gene deletion, which progressed to total loss in the last recurrence. The last recurrence showed homozygous deletions in CDKN2A and CDKN2B. The RASSF1 gene was hypermethylated during tumour evolution. In this report, we show the genetic alterations of a primary CCM and its recurrences to elucidate their relationships with the changes involved in the progression of this rare neoplasm. [ABSTRACT FROM AUTHOR]

Background: In this study, we reported seven cases of pediatric intracranial clear cell meningiomas (CCMs) in our institution and reviewed the relevant literature to investigate the clinicopathological characteristics, treatment options, and prognosis of these rare tumors. Methods: From January 2005 to June 2016, we retrospectively reviewed seven pediatric intracranial CCMs in terms of their clinical data, preoperative MRI features, and prognosis. Moreover, a critical review of the English language literature was also conducted. Results: The patients consisted of two males and five females with a median age of 10.5 years (range 6-15 years) at initial surgery. Petroclival and cerebellopontine angle area was the most common location site (5/7). Accordingly, the most common initial manifestation was hearing loss (3/7), and the mean interval from onset of symptoms to admission was 6.8 months (1.5-24 months). Gross total resection was achieved in five patients. Of the six tumors with immunohistochemical records, MIB-1 labeling index varied from 3 to 20 % (mean 8.1 %). During the follow-up period (mean 76.9 months, range 16-180 months), four patients had experienced tumor recurrences and three patients died due to recurrences. Conclusions: Pediatric intracranial CCMs have a tendency to recur. There is a significant relationship between MIB-1 labeling index and recurrence. Gross total resection is recommended; if not available, adjuvant radiotherapy should be used to reduce the recurrent rate. In addition, postoperative MRI follow-up should be monitored at an interval time after resection. [ABSTRACT FROM AUTHOR]