Characteristic features and proposed classification in 69 cases of intracranial microcystic meningiomas

Posterior fossa microcystic meningioma mimicking an arachnoid cyst

Microcystic meningioma is an uncommon subtype of World Health Organization grade 1 meningiomas often associated with a shorter progression-free survival. Diagnosis through imaging alone can often be challenging due to atypical characteristics, especially when found in unexpected locations. Here, we present a 55-year-old woman who was diagnosed, based on imaging, with a posterior fossa arachnoid cyst 5 years prior after complaints of headaches and gait imbalance. After surgical resection of the "arachnoid cyst," the diagnosis of microcystic meningioma was made. This case report emphasizes the clinical importance and challenges associated with diagnosing microcystic meningiomas.

Intravenous tranexamic acid for intracerebral meningioma resections: A randomized, parallel-group, non-inferiority trial

STUDY OBJECTIVES

Tranexamic acid (TXA) is an antifibrinolytic that is widely used to reduce surgical bleeding. However, TXA occasionally causes seizures and the risk might be especially great after neurosurgery. We therefore tested the hypothesis that TXA does not meaningfully increase the risk of postoperative seizures within 7 days after intracranial tumor resections.

DESIGN

Randomized, double-blind, placebo-controlled, non-inferiority trial.

SETTING

Beijing Tiantan Hospital, Capital Medical University.

PATIENTS

600 patients undergoing supratentorial meningioma resection were included from October 2020 to August 2022.

INTERVENTIONS

Patients were randomly assigned to a single dose of 20 mg/kg of TXA after induction (n = 300) or to the same volume of normal saline (n = 300).

MEASUREMENT

The primary outcome was postoperative seizures occurring within 7 days after surgery, analyzed in both the intention-to-treat and per-protocol populations. Non-inferiority was defined by an upper limit of the 95% confidence interval for the absolute difference being <5.5%. Secondary outcomes included incidence of non-epileptic complication within 7 days, changes in hemoglobin concentration, estimated intraoperative blood loss. Post hoc analyses included the types and timing of seizures, oozing assessment, and a sensitivity analysis for the primary outcome in patients with pathologic diagnosis of meningioma.

MAIN RESULTS

All 600 enrolled patients adhered to the protocol and completed the follow-up for the primary outcome. Postoperative seizures occurred in 11 of 300 (3.7%) of patients randomized to normal saline and 13 of 300 (4.3%) patients assigned to tranexamic acid (mean risk difference, 0.7%; 1-sided 97.5% CI, -∞ to 4.3%; P = 0.001 for noninferiority). No significant differences were observed in any secondary outcome. Post hoc analysis indicated similar amounts of oozing, calculated blood loss, recurrent seizures, and timing of seizures.

CONCLUSION

Among patients having supratentorial meningioma resection, a single intraoperative dose of TXA did not significantly reduce bleeding and was non-inferior with respect to postoperative seizures after surgery.

REGISTRY INFORMATION

This trial was registered at clinicaltrials.gov (NCT04595786) on October 22, 2020, by Dr.Yuming Peng.

Utility of Apparent Diffusion Coefficient Histogram Analysis in Differentiating Microcystic Meningioma from Intracranial Solitary Fibrous Tumor

BACKGROUND

To investigate the possibility of histogram analysis of apparent diffusion coefficient (ADC) maps in differentiating microcystic meningioma (MM) from intracranial solitary fibrous tumor (SFT).

METHODS

Eighteen patients with MM and 23 patients with SFT were enrolled in this retrospective study. Conventional magnetic resonance imaging (MRI) features and 9 ADC histogram parameters (including mean, first (ADC1), 10th (ADC10), 50th (ADC50), 90th (ADC90), and 99th (ADC99) percentiles ADC, as well as variance, skewness, and kurtosis) between MM and SFT were compared. The diagnostic performance of the optimal parameter was determined by the receiver operating characteristic analysis.

RESULTS

SFT showed a significantly lower mean, ADC1, ADC10, ADC50, ADC90, and ADC99 than MM (all P < 0.05), while no significant difference was found in conventional MRI features or other ADC histogram parameters (all P > 0.05). ADC1 was identified as the optimal parameter in differentiating between MM and SFT, which achieved an area under the curve of 0.861, with sensitivity, specificity, and accuracy of 78.26%, 88.89%, and 82.93%, respectively.

CONCLUSIONS

MM and SFT show overlapping conventional MRI features. ADC histogram analysis helps to differentiate between MM and SFT, with ADC1 being the optimal parameter with the best discrimination performance.

Distinct clinical outcome of microcystic meningioma as a WHO grade 1 meningioma subtype

OBJECTIVE

To evaluate the clinicopathological characteristics, radiology, and long-term outcomes of microcystic meningiomas (MM) and compare it with other subtypes of meningiomas managed at a single neurosurgical center.

METHODS

A total of 87 consecutive patients who underwent surgical resection and were diagnosed as MM between 2005 and 2016 were enrolled for analysis. Clinicopathological, radiology, and prognostic information was collected and analyzed. Progression free survival (PFS) was compared with 659 patients with other subtypes of WHO grade 1 meningiomas and 167 patients with atypical meningiomas treated during the same period.

RESULTS

Fifty six females and 31 males with MM were analyzed. Peri-tumor brain edema was frequent on T2 WI (85%).12 patients (13.8%) experienced tumor progression during the mean follow-up of 101.66 ± 40.92 months. The median PFS was unavailable, and the 5, 10, and 15 year progression-free rates were 96.9%, 84.0%, and 73.9%, respectively. Univariate COX analysis demonstrated skull base location and higher Ki-67 index as significant negative prognostic factors for PFS (P < 0.05); multivariate analysis identified tumor location and Ki-67 index as independent factors (P < 0.01), as well. Of note, the PFS of MM was worse than other WHO grade 1 subtypes (P < 0.001), but better than atypical meningiomas (P < 0.001), and the PFS differences were retained even when the analysis was limited to the patients receiving GTR (P < 0.05).

CONCLUSION

The PFS of MM was worse than other WHO grade 1 subtypes and better than atypical meningiomas. Skull base location and higher Ki-67 index were independent negative prognostic factors in MM.

Discrimination between microcystic meningioma and atypical meningioma using whole-lesion apparent diffusion coefficient histogram analysis

AIM

To explore the value of whole-lesion apparent diffusion coefficient (ADC) histogram analysis in discriminating microcystic meningioma (MCM) from atypical meningioma (AM).

MATERIALS AND METHODS

Clinical and preoperative MRI data of 20 patients with MCM and 26 patients with AM were analysed retrospectively. Whole-lesion apparent diffusion coefficient (ADC) histogram analysis was performed on each patient's lesion to obtain histogram parameters, including mean, variance, skewness, kurtosis, the 1st (ADCp1), 10th (ADCp10), 50th (ADCp50), 90th (ADCp90), and 99th (ADCp99) percentiles of ADC. The differences between the ADC histogram parameters of the two tumours were compared, and the receiver operating characteristic (ROC) curve was used to assess the diagnostic performance of statistically significant parameters in distinguishing the two tumours.

RESULTS

The mean, ADCp1, ADCp10, ADCp50, and ADCp90 of MCM were greater than those of AM, and significant differences were observed in these parameters between MCM and AM (all p<0.05). ROC analysis showed that the mean had the highest area under the curve value (AUC) in distinguishing the two tumours (AUC = 0.852), when using 120.46 × 10^-6 mm²/s as the optimal threshold, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for discriminating the two groups were 84.6%, 75%, 80.4%, 81.5%, and 78.9%, respectively.

CONCLUSION

Histogram analysis based on whole-lesion ADC maps was useful for discriminating between MCM from AM preoperatively, with the mean being the most promising potential parameter.

Imaging Features and Pathological Correlation in Mixed Microcystic and Angiomatous Meningioma: A Case Report

Meningiomas are the most common intracranial tumors. However, microcystic and angiomatous meningiomas are very rare subtypes that present unusual imaging findings. Hence, radiological diagnosis of these tumors can be challenging. We herein describe a case of mixed angiomatous and microcystic meningioma in an 81-year-old male. MRI revealed an extra-axial mass with high T2 signal intensity, measuring 1.5 cm in diameter, with multiple tiny intralesional cysts and entrapped peritumoral cyst formation. After tumor resection, a histopathological diagnosis of mixed angiomatous and microcystic meningioma was made.

Comparative analysis of magnetic resonance imaging and pathological findings of microcystic meningioma and meningeal Ewing sarcoma/peripheral primitive neuroectodermal tumors

Microcystic meningiomas (MCMs) and meningeal Ewing sarcoma/peripheral primitive neuroectodermal tumours (pPNETs) are difficult to differentiate because of the similarity in their image manifestation on magnetic resonance imaging (MRI). Differential diagnosis of these two tumours before surgery could contribute to ameliorating clinical decision-making, and predicting prognosis. Here, we aimed to comparatively analyse the difference between MRI and pathological findings of these two tumours. Thirteen cases of MCM and eleven cases of meningeal Ewing sarcoma/pPNET confirmed through pathology were analysed retrospectively. The imaging features of the two tumours were statistically analysed using the Chi square test. The average age of patients with MCM and meningeal Ewing sarcoma/pPNET was 47 ± 18.4 years and 20 ± 13.2 years, respectively. Features of MRI, including tumour morphology, dural tail sign, bony destruction, and distant metastasis, were significantly different between the two tumours (p < 0.001). T1-weighted (T1W) signal and enhanced features resulted in a p value of < 0.05. There were no significant differences in the T2-weighted (T2W) signal and peri-tumoural oedema (p > 0.05). MCM immunohistochemistry showed that all the cases were positive for vimentin (Vim), epithelial membrane antigen (EMA), and the ki-67 index was less than 5%, while all the cases of meningeal Ewing sarcoma/pPNET were positive for Vim and CD99, and the ki-67 index was more than 30%. MRI imaging features of MCMs and meningeal Ewing sarcoma/pPNETs were different. Accurate preoperative diagnosis of these two tumours is helpful in implementing a clinical surgical plan and further management. Moreover, imaging combined with pathology can explain the imaging characteristics better.

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.