Impact on natural history of atypical meningioma after changes in 2016 edition of the world health organization (WHO) classification of central nervous system tumors: a literature review.

Meningiomas and their WHO histological diagnostic criteria is complex, especially for grade 2 tumors presenting a interobserver discordance as high as 12.2%. The 2016 edition of the WHO Classification of CNS tumors recommended brain invasion as a stand-alone grading criterion for diagnosing an atypical grade 2 meningioma (AM). To provide an overview of the classification of 2016 WHO impact on the natural history of atypical meningioma (AM) relative to previous classification. To achieve this goal, we selected articles from the period 2017-2024 in Medline search on atypical meningiomas and analyzed them after following the following criteria: 1) reports with confirmed histopathological diagnosis according to WHO 2016 and or 2021 criteria; 2) series and case reports; 3) detailed and individualized clinical outcomes for AM; and 4) papers written in English; after that a total of 3445 patients reported in 67 manuscripts from worldwide centers from 2017 to March 2024 were analyzed. The patient's age at the time of surgery ranged from 1 month to 97 years (mean 52.28 ± 18.7 years). The most common tumor site was the convexity, accounting for 67.8%, followed by the skull base in 30.6%, ventricle in 1%, and spine in 0.6%; Gross total resection (GTR) was performed in 71.25% and subtotal resection (STR) in 28.75%; 1021 patients (29.63%) underwent adjuvant radiotherapy, and 22 patients (0.6%) were treated with adjuvant chemotherapy; tumor recurrence was reported in 1221 patients (35.44%) and 859 deaths (24.93%). 1) AM prevalence in females; 2) AM age distribution similar to the distribution of meningiomas in general; 3) AM recurrence rate of 35.44%, despite the high rate of GTR, which was higher than previously reported; 4) deepening knowledge in molecular mechanism of tumor progression will provide alternative therapeutic approaches for AM.

Surgery alone versus surgery plus adjuvant radiotherapy for WHO grade 2 meningioma: meta-analysis of reconstructed time-to-event data.

INTRODUCTION: WHO Grade 2 meningiomas present diagnostic and management challenges. Surgery, particularly gross total resection (GTR), is crucial, often followed by adjuvant radiotherapy (RT); however, there are clinical equipoise and ongoing randomized trials of RT after GTR. METHODS: This systematic review evaluates the efficacy of gross total resection (GTR) and GTR plus adjuvant radiotherapy (RT) for WHO grade 2 meningiomas, adhering to PRISMA guidelines. It excludes irrelevant studies, conducts a thorough search until January 2024, and specifically analyzes overall survival (OS) and progression-free survival (PFS) outcomes for WHO grade 2 meningiomas. Statistical analysis adopts a two-stage approach with the R package "IPDfromKM," and quality assessment is conducted using the ROBINS-I tool. RESULTS: In our analysis of 23 studies involving 3822 WHO grade 2 meningioma patients, GTR + RT resulted in a significantly longer PFS (HR: 0.849, 95% CI: 0.730 to 0.988, p = 0.035) compared to GTR alone. Although OS trended better with GTR + RT (HR: 0.79, 95% CI: 0.57 to 1.11, p = 0.173), the difference was not statistically significant, suggesting the need for further investigation. CONCLUSION: Our study reveals a benefit to adjuvant RT for improving PFS for WHO grade 2 meningiomas. Integrating molecular characteristics into treatment strategies will refine the management of these tumors in the future.

Extracerebral Pterional Metastasis from Malignant Meningioma: A Case Report

Anaplastic or malignant meningiomas that are classified as World Health Organization (WHO) grade III account for less than 1% of all meningiomas diagnosed. Despite the aggressive course, distant metastases are a rarity, occurring in only 0.1% to 0.2% of cases. We report the case of a 56-year-old woman who presented with parasagittal benign meningioma that underwent malignant transformation along with metastasis into the right orbitosphenoid region. The clinical, radiological, and histopathological aspects are highlighted, with an emphasis on the natural history of meningiomas.

Impact of radiotherapy in atypical meningioma recurrence: literature review.

Evaluate whether radiotherapy (RT) after the neurosurgical treatment of atypical meningiomas (AM) has an impact on the reduction rate of recurrence. A Medline search through October 2017 using "atypical meningioma" returned 1277 papers for initial review. Inclusion criteria were as follows. We analyzed the database and included articles in which the anatomic pathological classification of atypical meningiomas was in accordance with WHO 2007 or WHO 2016 criteria, patients > 18 years of age, and there was postoperative external beam radiation to the tumor bed. Exclusion criteria were WHO grade I or III meningioma, patients who underwent whole-brain radiation, RT used as salvage therapy for recurrence, palliative dose of RT (< 45 Gy), recurrent AMs, and multiple AMs. Papers reporting outcomes in which atypical and anaplastic meningiomas were analyzed together were rejected, as were papers with small samples that may compromise evaluation. After filtering our initial selection, only 17 papers were selected. After reviewing the seventeen articles including a total of 1761 patients (972 female and 799 male; 1.21 female/1.0 male), the difference in proportion of tumor recurrence between patients with and without radiotherapy after neurosurgical procedure was 1.0448, 95% CI [0.8318 to 1.3125], p value = 0.7062. On the basis of this review, there is no evidence to suggest that RT decreases the rate of recurrence in patients with atypical meningiomas.

Atypical and Malignant Meningiomas: Neurooncologic Management in a Brazilian cohort.

OBJECTIVE: To analyze the surgical and oncologic treatment of a Brazilian cohort of patients with grade II and III meningioma at a follow-up time of 15 years to get an overview of these patients' outcomes. METHODS: Cross-sectional study of 43 patients (26 women, 17 men; age range 20 to 83 years; average 57.72 ± 14.54) operated on from 2000 to 2014 at a single institution, with the neuropathologic diagnosis of meningioma grade II (39 patients) and grade III (4 patients). RESULTS: Radiotherapy: 24 patients (55.81%) underwent radiotherapy; the time between the surgical procedure and the beginning of radiotherapy was 5 months; 7 patients with a diagnosis of AM underwent a new surgical procedure, albeit of adjuvant therapy, because of tumor recurrence, and only 3 of them underwent radiotherapy after the first resection. Mortality: in total, 19 deaths (44.18%) were identified in this sample: 15 (38.46%) with GII and 4 (100%) with GIII. The 10-year survival was expected in 35% of GII patients and 0% of GIII patients. CONCLUSION: Surgery is still the main form of treatment and the mainstay for prolonging survival. Radiotherapy is still controversial; however, we observed its positive impact on recurrence and progression-free survival.