Clear Cell Meningioma: Clinical Features, CT, and MR Imaging Findings in 23 Patients

Adjuvant Stereotactic Radiosurgery for Clear Cell Meningiomas

OBJECTIVE

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.

METHODS

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).

RESULTS

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.

CONCLUSIONS

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.

Lumbar clear cell meningioma mimicking schwannoma 7 years after resection of the same type of intracranial tumor: a case report

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.

Favorable Long-Term Outcomes of Chordoid Meningioma Compared With the Other WHO Grade 2 Meningioma Subtypes

BACKGROUND

WHO grade 2 meningiomas, including atypical, chordoid, and clear cell subtypes, form a heterogenous group of meningiomas with varying aggressiveness and clinical behavior.

OBJECTIVE

To demonstrate the differences of clinical-histopathological characteristics and long-term outcomes among these 3 subtypes.

METHODS

A total of 609 consecutive patients diagnosed with WHO grade 2 meningiomas (543 atypical meningiomas [AMs], 36 chordoid meningiomas [CMs], and 30 clear cell meningiomas [CCMs]) from 2010 to 2018 were enrolled in this study. We compared the clinical-histopathological characteristics and long-term outcomes in these 3 subtypes and assessed survival differences among the subtypes. Targeted panel sequencing of meningioma-relevant genes was performed in the cases of CM.

RESULTS

The patients with CCM were significantly younger than those with AM ( P < .001) and CM ( P = .016). CMs were more likely to receive gross total resection than AMs and CCMs ( P = .033). The Ki-67 index was lower ( P < .001) while the progesterone receptors-positive rate was higher ( P = .034) in CM than in AM and CCM. Importantly, survival analysis demonstrated that CM had better progression-free survival ( P = .022) and overall survival ( P = .0056) than non-CM tumors. However, the PFS of CM was still worse than WHO grade 1 meningiomas ( P < .001). Alterations in NF2 (20.6%) and KMT2C (26.5%) were associated with poorer PFS in CM ( P = .013 for NF2 ; P = .021 for KMT2C ).

CONCLUSION

Patients with CM had better long-term postoperative outcomes than the other WHO grade 2 subtypes. A lower Ki-67 index, higher PR status, higher extent of resection, and lower frequency of NF2 alteration might contribute to favorable clinical outcomes of CM.

Outcomes following surgical resection of cystic intracranial meningiomas

INTRODUCTION

Cystic meningiomas are rare, accounting for 2-7% of all intracranial meningiomas. Little is known regarding whether these meningiomas behave differently compared to solid meningiomas. We sought to study this relatively uncommon imaging appearance of meningioma and to evaluate its clinical significance.

METHODS

A single-institution retrospective cohort study of surgically-treated meningioma patients between 2000 and 2019 was conducted. Cystic meningioma was defined as a tumor with an intratumoral or peritumoral cyst present on preoperative imaging. Demographics, preoperative imaging, histopathology characteristics, operative data, and surgical outcomes were reviewed. Imaging variables, histopathology and outcomes were reported for cystic meningiomas and compared with non-cystic meningiomas. Univariate/multivariable analyses were conducted.

RESULTS

Of 737 total meningiomas treated surgically, 38 (5.2%) were cystic. Gross total resection (GTR) was achieved in 84.2% of cystic meningioma patients. Eighty-two percent of cystic meningiomas were WHO grade I (n = 31), 15.7% were grade II and 2.6% were grade III. Most cystic meningiomas had low Ki-67/MIB-1 proliferation index (n = 24, 63.2%). A total of 18.4% (n = 7) patients with cystic meningioma had recurrence compared to 12.2% (n = 80) of patients with non-cystic meningioma (p = 0.228). No significant difference in median time to recurrence was observed between cystic and non-cystic meningiomas (25.4, Q1:13.9, Q3:46.9 months vs. 13.4, Q1:8.6, Q3:35.5 months, p = 0.080).

CONCLUSIONS

A small portion of intracranial meningiomas have cystic characteristics on imaging. Cystic meningiomas are frequently WHO grade I, have low proliferation index, and had similar outcomes compared to non-cystic meningioma. Cysts in meningioma may not be a surrogate to determine aggressive meningioma behavior.

Spinal clear cell meningioma without dural attachment: a case report and literature review

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.

Paediatric supra- and infratentorial multiple giant clear cell meningioma: A report of a rare case and review of the literature

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.

Clinical Manifestation, Management and Prognosis of Clear Cell Meningioma: An Evidence-Based Review

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.

Venous Anatomy Influence on the Approach Selection of a Petroclival Clear Cell Meningioma With Associated Multiple Spinal Meningiomas: 2-Dimensional Operative Video

Preoperative careful evaluation of the sigmoid transverse sinus and its tributary veins is paramount for the safe surgical planning of petroclival lesions.1,2 When the vein of Labbé is running within the tentorium, classic petrosal approach involving transection of the tentorium is modified to avoid the risk of postoperative morbid temporal lobe venous infarcts.1-3 Thus, the surgical plan should be tailored to the specific patient anatomy as demonstrated in the presented case during which a transmastoid approach was followed, in the same surgical setting, by a middle fossa approach to resect a large petroclival clear cell meningioma with extension into Meckel cave. These meningiomas are WHO grade II tumors with a propensity to local recurrence and cerebrospinal fluid seeding.4 SMARCE1 mutations define this subtype of meningioma, with frequent familial inheritance, and predispose patients to both skull base and spinal clear cell meningiomas.5,6 Maximal surgical resection is the best initial treatment option allowing to withhold or delay the use of radiation in tumors frequently encountered in young patients.7 In this report, we demonstrate the microsurgical techniques deployed to achieve maximal resection of a petroclival clear cell meningioma and associated lumbar and sacral spinal meningiomas in a 20-yr-old patient with a familial SMARCE1 mutation. The patient agreed to the surgical intervention and to the use of her image.

Clear cell histology portends a worse prognosis than other WHO grade II histologies

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.

Intraoperative Anatomical Findings in Pediatric Clear Cell Meningioma of the Lumbar Spine: Case Report and Literature Review

Clear cell meningioma (CCM) is a WHO classification Grade II meningioma. It is a very rare disease, of which only 41 cases of spinal cord CCM in children have been reported to date. CCMs sometimes do not have the “dural attachment” that is usually found in meningiomas, and our understanding of the origin of CCMs is therefore controversial. We hereby present a case of pediatric CCM of the lumbar spine, in which we examined intraoperatively, the detailed anatomical location of the tumor. The case is a 10-year-old boy, who presented to our hospital with a 2-month history of lower back and bilateral lower extremity pain upon waking, which gradually worsened. Lumbar spine CT and MRI revealed an intradural extramedullary tumor at the L3 vertebral level, and surgery was performed to remove it. The tumor was in close contact with the dura mater, and also in contact with the cauda equina via the arachnoid. The tumor was likely located primarily between the dura mater and arachnoid. The pathological diagnosis was CCM, with an MIB-1 index of less than 1%. His back pain and bilateral lower extremity pain improved after surgery, and he was discharged from our hospital. Postoperative radiation therapy was not performed. Based on this case, we suggest that intraoperative examination of the anatomical location of these tumors and accumulation of relevant experience are important to elucidate the embryological mechanisms of this rare disease.

Absence of contrast enhancement in a petroclival meningioma: Case report and systematic literature review

Background:

Meningioma is one of the most common intracranial tumors with well-established radiologic features such as contrast enhancement, dural tail, and hyperostosis on computed tomography and magnetic resonance imaging. Contrast enhancement is usually homogeneous or heterogeneous based on tumor vascularity and underlying histopathology. Even in this context, faint or nonenhancing meningioma is exceedingly rare.

Case Description:

A 57-year-old male presented with progressive right hearing loss, disequilibrium, occasional difficulty swallowing, and facial numbness. Imaging demonstrated an extensive hypodense, nonenhancing right cerebellopontine angle mass extending from the interpeduncular, and ambient cisterns to the foramen magnum. The pathological analysis demonstrated a microcystic meningioma WHO Grade I. There are few reported case reports or series of minimal or nonenhancing meningiomas, and a systematic review was performed for these cases. Seven peer-reviewed articles with 14 verifiable cases were identified and reviewed for radiologic features, tumor location, and tumor classification. The majority of minimal or nonenhancing meningiomas were microcystic, and most of them located at the convexity. This is the second case reported of a nonenhancing meningioma at the cerebellopontine angle and petroclival region

Conclusion:

Meningioma should be considered a differential diagnosis for nonenhancing lesion at the cerebellopontine and petroclival regions.

Rare intraspinal clear cell meningioma in children: a case report and literature review

Meningioma of the spinal canal is very rare. Clear cell meningioma (CCM) with special histological features occurs more commonly in the spinal cord. A review of the published English-language literature identified 40 reported cases of children with intraspinal CCM and this current report presents an additional case of a 3-year-old child with confirmed lumbar CCM. The current case underwent gross total resection of the CCM. At 9 months after the operation, lumbar magnetic resonance imaging was undertaken and confirmed the absence of tumour recurrence. The child was able to walk normally again. During this period, the child did not receive adjuvant treatments such as radiotherapy and chemotherapy. An evaluation of the 41 cases demonstrated the following: (i) there was no significant difference between the recurrence rate of females and males; (ii) there was a significant difference in the recurrence rate based on the extent of resection (gross total resection versus partial resection); (iii) the recurrence rate in patients where the number of involved segments ≥3 levels was significantly higher than that in patients where the number of involved segments was 1–2 levels. For children with CCM, complete surgical resection might be an important characteristic for predicting the risk of the recurrence of CCM.

Clear Cell Meningioma: A Clinicopathologic Study of a Rare Meningioma Subtype in 35 Patients

OBJECTIVE

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

An Aggressive Extension of Dumbbell-Type Pediatric Skull Base Meningioma: A Case Report with Review of the Literature

BACKGROUND

Pediatric meningiomas account for less than 2% of pediatric brain tumors. Pediatric clear cell meningiomas (CCMs) occurring in the posterior fossa are particularly rare. Therapeutic strategies differ among the previous pediatric CCM case reports. Therefore, to clarify the clinical features of pediatric CCMs, we report a rare case of dumbbell-type pediatric CCM and a corresponding literature review.

CASE DESCRIPTION

A 7-year-old boy with complaints of headache, left facial palsy, dysarthria, and left-sided ataxic gait was emergently admitted to our hospital. His consciousness level was slight stupor, with Glasgow Coma Scale score 3-5-6, and he showed left ptosis, dysarthria, and ataxias of the left trunk and extremities. Magnetic resonance imaging (MRI) scan showed acute obstructive hydrocephalus because of the tumor's compression of the brainstem. The dumbbell-shaped tumor extended from the lateral wall of the cavernous sinus, through the left Meckel's cave, to the cerebellopontine angle. Physical examination and perioperative MRI scan showed no evidence regarding neurofibromatosis type I or II. The tumor was removed in a 2-staged operation. Postoperative proton therapy was done to treat some residual tumors. One year after postoperative proton therapy, there is no recurrence, and apart from left corneal and facial hypesthesia, he is healthy.

CONCLUSIONS

We reported a rare case of pediatric skull base-type CCM with huge extension originating from the anteromedial wall of Meckel's cave firmly adhered to the cavernous sinus wall to the posterior fossa that was successfully treated with surgery and postoperative proton therapy. CCM has a high recurrence rate; therefore, careful prolonged follow-up is needed.

Imaging spectrum of meningiomas: a review of uncommon imaging appearances and their histopathological and prognostic significance

Meningiomas are the most common primary non-glial intracranial neoplasms. In most cases, meningiomas have typical imaging appearances and locations, enabling a straightforward radiological diagnosis. However, a myriad of unusual appearances potentially complicate the imaging picture. Furthermore, certain imaging features can also predict the specific histopathological nature and WHO grade of the meningioma. 'Typical' meningiomas include meningothelial, fibrous, and transitional variants and have the characteristic imaging features described for meningiomas. Several 'atypical' variants exist, which, although less common, also generally have a less favourable prognosis and necessitate early diagnosis. In addition, meningiomas can occur in a variety of unusual intracranial and even extra-cranial locations and need to be distinguished from the more common tumours of these regions on imaging. Any associated oedema or haemorrhagic changes may alter the prognosis and have to be carefully assessed and reported. Cystic changes in meningiomas have been divided into five subtypes, and accurate characterisation is essential to predict the prognosis. An extensive review of the several possible variations in imaging appearances of meningiomas including the differential features of common and uncommon variants would facilitate informative radiological reporting of meningiomas. This would be expected to improve pre-operative planning prior to surgical biopsy and thereby improve disease prognosis and patient outcomes.

Spinal Clear Cell Meningiomas: Clinical Features and Factors Predicting Recurrence

OBJECTIVE

As a World Health Organization grade II tumor of the nervous system, clear cell meningioma (CCM) is an uncommon histologic variant of meningioma. Spinal CCMs are even rarer, with <100 spinal CCMs reported in the English literature. We present this study to characterize clinical manifestations of spinal CCMs and determine the factors predicting recurrence.

METHODS

A literature search was performed for relevant case reports and series in PubMed and Embase until September 1, 2019. These articles were reviewed to identify clinical features, treatment modalities, and prognosis of patients with spinal CCMs.

RESULTS

Eighty-four spinal CCMs were analyzed. Of these patients, 36 (42.9%) were young (age ≤18 years), and the mean age at resection was 24 years. Fifty-three patients (63.1%) were female and 31 (36.9%) were male. Most of the tumors (56/84, 66.7%) were located in the lumbar region. In 31 patients (36.9%) >2 segments in the craniocaudal direction were involved (number of involved segments ≥3 levels). Gross tumor resection was performed in 77 patients (91.7%). Twenty patients (23.8%) showed radiographic evidence of recurrence during follow-up. Recurrence-free survival at 1, 5, and 10 years after resection of spinal CCM was 87%, 71%, and 47%, respectively. Multivariate analysis showed that age ≤18 years (hazard ratio [HR], 3.64; P = 0.024), subtotal resection (HR, 3.43; P = 0.031), and segments involving ≥3 levels (HR, 5.66; P = 0.002) were associated with increased recurrence.

CONCLUSIONS

Spinal CCMs have their own unique clinical features compared with conventional spinal meningiomas and intracranial CCMs. Spinal CCMs have a predilection to affect younger patients, are prone to appear in the lumbar region, and have a high recurrence rate. Age ≤18 years, subtotal resection, and involvement of long segments (≥3 levels) are positive predictors of recurrence.

A case report on cystic meningioma in cerebellopontine angle and recommendations for management

RATIONALE

Cystic meningioma located at the cerebellopontine angle (CPA) is an extremely rare occurrence. It is frequently misdiagnosed preoperatively. Little is known about the clinical features and outcome of this rare disease.

PATIENT CONCERNS

A 70-year-old male presenting with progressive headache and gait disturbance.

DIAGNOSIS

According to the symptoms, signs, and Gd-enhanced magnetic resonance images (MRI), a preoperative diagnosis of hemangioblastoma located in left CPA was made. Finally, the histological examination revealed a meningioma.

INTERVENTIONS

A complete resection, including the part of the solid mass together with cyst, was performed.

OUTCOMES

The postoperative course of the patient was uneventful, and no residual or recurrent tumor was found during the 24-month follow-up period.

LESSONS

Cystic meningioma should be included in the differential diagnosis of a CPA mass with atypical radiologic features, such as a large cyst and enhanced mural nodule. By summarizing the related literature, we found that the most common pathological subtype of CPA cystic meningioma is the clear cell subtype, which belongs to WHO grade II. Gross total resection including the enhanced cyst wall is extremely important. A close follow-up is necessary because of the high recurrence rate in this subset of meningioma.

Spinal Clear Cell Meningioma: Clinical Study with Long-Term Follow-Up in 12 Patients

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.

Pediatric nondura-based clear cell meningioma of the cauda equina: case report and review of literature

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.

Clinical Features, Treatment, and Prognostic Factors of 56 Intracranial and Intraspinal Clear Cell Meningiomas

OBJECTIVE

Intracranial and intraspinal clear cell meningiomas (CCMs) are rarely reported because of their extremely low incidence, and the current understanding of CCM is poor. The purpose of this study was to analyze the incidence and the clinical, radiologic, pathologic, and prognostic features of intracranial and intraspinal CCMs.

METHODS

Among 14,310 cases of intracranial and intraspinal meningiomas that were surgically treated between 2006 and 2016 at Beijing Tian Tan Hospital, 56 were chosen for analysis and retrospectively reviewed. To determine which parameters were associated with longer progression-free survival (PFS) and overall survival (OS), statistical analysis was performed.

RESULTS

CCMs accounted for approximately 0.39% of all intracranial and intraspinal meningiomas. Patients with CCM had a mean age of 32.3 years and there was a female predilection (20 males and 36 females). Gross total resection was achieved in 35 cases, and subtotal resection was achieved in 21 cases. All patients were followed up for 10-206 months after surgery. Twenty-six patients experienced tumor recurrence, and the median PFS was 48.0 months. The 1-year, 3-year, and 5-year PFS was 87.5%, 59.8%, and 41.8%, respectively. Twelve patients died of tumor recurrence, and the median OS was not available. The 1-year, 3-year, and 5-year OS was 98.2%, 91.3%, and 65.8%, respectively. Univariate analysis showed that total tumor removal was significantly associated with a better prognosis. Multivariate analysis confirmed only Simpson grade III and IV resection as an independent risk factor for shorter PFS. Radiotherapy mildly improved PFS after both gross total resection and subtotal resection, showing no significant difference because of the small sample size and short follow-up duration.

CONCLUSIONS

CCM is a rare subtype of World Health Organization grade II meningioma. CCM typically involves young patients and shows a female predilection and high recurrence rate. When possible, total resection is the primary and most suitable treatment for CCM. For patients with primary tumors, radiotherapy is recommended after the initial operation regardless of the extent of resection. For patients with disease recurrence, secondary surgery combined with radiotherapy might serve as an effective treatment.

Molecular progression in unusual recurrent non-pediatric intracranial clear cell meningioma

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.

Pediatric infratentorial meningiomas: a series of 19 cases and review of the literature

PURPOSE

Pediatric infratentorial meningiomas are extremely rare. In this article, we present a series of 19 cases operated at our institution in the last 8 years.

METHODS

During the 8-year period from January 2008 to December 2015, we encountered 21 cases suffered from infratentorial meningiomas. Two patients were excluded. The clinical profiles, radiological features, surgical procedures, intraoperative findings, and outcomes were extracted from the patient records and neuroimaging data.

RESULTS

The 19 cases with pediatric infratentorial meningiomas account for about 12.8% of all pediatric intracranial meningiomas. The age distribution of the patients ranged from 7 to 18 years. There were 9 male and 10 female patients. Cranial nerve defects were the first common signs and symptoms found in most cases (n = 14). One meningioma localized in cerebellum, one originated in jugular foramen. Meningioma involving internal auditory canal was only seen in one of the six patients with CPA meningioma. One tumor was totally ossified. In all, total resection was achieved in 14 patients, subtotal resection in 5 patients. Gamma knife was used for the recurrent and subtotally resected tumors. Conventional radiotherapy was applied for high-grade meningiomas (WHO grade II and WHO grade III).

CONCLUSION

Pediatric infratentorial meningiomas are different from supratentorial ones in many aspects, such as onset age, gender ratio, and neuroradiological characteristics. Surgical excision is challenging. According to the locations of tumors, different surgical approaches would be chosen to maximally resect the lesions without damage to brain stem and cranial nerves. Gamma knife and conventional radiotherapy could be used as postoperative adjuvant therapies. Long-term clinical follow-up and serial imaging are recommended.

Pediatric intracranial clear cell meningioma: a clinicopathological study of seven cases and literature review

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.

Cystic meningioma: radiological, histological, and surgical particularities in 43 patients

BACKGROUND

The presence of cysts is a rare occurrence for intracranial meningiomas in adults. We report our experience in a large consecutive series of cystic meningiomas.

METHOD

We prospectively collected data for a dedicated database of cystic meningioma cases between January 2004 and December 2011 in two tertiary neurosurgical centers. Studied data included preoperative imaging, surgical records, and pathology reports.

RESULTS

Among 1214 surgeries for intracranial meningioma, we identified 43 cases of cystic meningioma, corresponding to an incidence of 3.5 %. The most common localization was the hemispheric convexity (17/43 cases). Twenty-eight patients had intratumoral cysts, nine peritumoral, and five mixed intra and extratumoral. In 29 patients with available diffusion imaging, ADC coefficients were significantly lower in grade II-III tumors compared to grade I (p = 0.01). Complete resection of the cystic components was possible in 27/43 patients (63 %); partial resection in 4/43 (9 %); in 6/43 (14 %) cyst resection was not possible but multiple biopsies were performed from the cystic walls; in another 6/43 (14 %) the cystic wall was not identified during surgery. Cells with neoplastic features were identified within the cyst walls at pathology in 26/43 cases (60 %). All patients were followed-up for 24 months; long-term follow-up was available only in 32 patients for an average period of 49 months (range, 36-96 months). No recurrence requiring surgery was observed.

CONCLUSIONS

Cystic meningiomas are rare. Cells with neoplastic features are often identified within the cyst walls. Complete cyst resection is recommendable when considered technically feasible and safe.

Variants of meningiomas: a review of imaging findings and clinical features

Meningiomas are common neoplasms that frequently occur in the brain and spine. Among the 15 histological subtypes of meningiomas in the WHO classification, the incidence of meningothelial meningiomas is the highest, followed by fibrous and transitional meningiomas. These three subtypes account for approximately 80 % of all meningiomas, and thus could be regarded as typical meningiomas. For this reason, other uncommon histological subtypes may be considered as imaging variants, and diagnosis is often challenging for radiologists solely based on imaging features of typical meningiomas. In addition to the histological subtypes, meningiomas arising in atypical locations could be easily mistaken for other lesions more commonly observed in those locations. The purpose of this article is to review characteristic clinical and imaging findings of uncommon meningiomas, including histological variants and meningiomas occurring in relatively rare locations.

Clinical features of clear cell meningioma: a retrospective study of 36 cases among 10,529 patients in a single institution

BACKGROUND

Clear cell meningioma (CCM) is a rare subtype of meningioma. We present the largest series of 36 CCMs and evaluate several prognostic factors of patient's clinical outcome.

METHODS

Thirty-six patients with pathologically confirmed CCM among a total of 10,529 meningioma patients were retrospectively reviewed.

RESULTS

CCM constituted 0.3 % of the intracranial meningiomas and 1.4 % of the intraspinal meningiomas. The male-to-female ratio (36 vs 64 %) for CCMs was similar to that for total meningiomas (28 vs 72 %) patients (chi-squared test, p = 0.3). The mean age at diagnosis of CCM patients (29.3 ± 18.4 years) was significantly younger than that of total meningiomas (49.8 ± 11.9 years) patients (t-test, p = 0). During the follow-up, 15 patients (42 %) suffered from tumor recurrence. The recurrence time ranged from 10 months to 12 years, with a median time of 29 months. Kaplan-Meier survival analysis showed that patients after total resection (Simpson grades I and II) had significantly longer progression-free survival (PFS) time than those after subtotal resection (Simpson grades III and IV) (log-rank test, p = 0.006). However, age (≤20 years or >20 years, p = 0.9), gender (p = 0.3), postoperative radiotherapy (p = 0.4), progesterone receptor staining (positivity or negativity, p = 0.2), and Ki-67 index (≤5 % or >5 %, p = 0.4) did not have significant effects on patients' PFS time.

CONCLUSIONS

The proportion of CCM in spinal meningiomas is likely to be much larger than that in intracranial meningiomas. CCMs should be resected totally when possible to decrease the risk of recurrence or prolong patient's PFS time.

Pathology and molecular genetics of meningioma: recent advances

Meningiomas are the most common intracranial primary neoplasm in adults. Although the spectrum of clinical and molecular genetic issues regarding meningiomas remains undefined, novel genetic alterations that are associated with tumor morphology, malignancy, or location have recently been discovered. This review focuses on recent advances in understanding of the heterogenous pathology of meningiomas, particularly on associations between the clinical, histological, etiological, epidemiological, and molecular genetical aspects of the neoplasm.