The importance of considering competing risks in recurrence analysis of intracranial meningioma.

BACKGROUND: The risk of recurrence is overestimated by the Kaplan-Meier method when competing events, such as death without recurrence, are present. Such overestimation can be avoided by using the Aalen-Johansen method, which is a direct extension of Kaplan-Meier that accounts for competing events. Meningiomas commonly occur in older individuals and have slow-growing properties, thereby warranting competing risk analysis. The extent to which competing events are considered in meningioma literature is unknown, and the consequences of using incorrect methodologies in meningioma recurrence risk analysis have not been investigated. METHODS: We surveyed articles indexed on PubMed since 2020 to assess the usage of competing risk analysis in recent meningioma literature. To compare recurrence risk estimates obtained through Kaplan-Meier and Aalen-Johansen methods, we applied our international database comprising ~ 8,000 patients with a primary meningioma collected from 42 institutions. RESULTS: Of 513 articles, 169 were eligible for full-text screening. There were 6,537 eligible cases from our PERNS database. The discrepancy between the results obtained by Kaplan-Meier and Aalen-Johansen was negligible among low-grade lesions and younger individuals. The discrepancy increased substantially in the patient groups associated with higher rates of competing events (older patients with high-grade lesions). CONCLUSION: The importance of considering competing events in recurrence risk analysis is poorly recognized as only 6% of the studies we surveyed employed Aalen-Johansen analyses. Consequently, most of the previous literature has overestimated the risk of recurrence. The overestimation was negligible for studies involving low-grade lesions in younger individuals; however, overestimation might have been substantial for studies on high-grade lesions.

Molecular predictors for decitabine efficacy in meningiomas - a pilot study.

PURPOSE: Effective chemotherapeutical agents for the treatment of meningiomas are still lacking. Previous in-vitro analyses revealed efficacy of decitabine (DCT), a DNA methyltransferase (DNMT) inhibitor established in the treatment of leukemia, in a yet undefined subgroup of meningiomas. METHODS: Effects of DCT on proliferation and viability was analyzed in primary meningioma cells by immunofluorescence and MTT assays, and cases were classified as drug responders and non-responders. Molecular preconditions for efficacy were analyzed using immunofluorescence for Ki67, DNMT1, and five oncogenes (TRIM58, FAM84B, ELOVL2, MAL2, LMO3) previously found to be differentially methylated after DCT exposition, as well as by genome-wide DNA methylation analyses. RESULTS: Efficacy of DCT (10µM) was found in eight (62%) of 13 meningioma cell lines 48 h after drug exposition (p < .05). DCT significantly reduced DNMT1 expression in all but two cell lines, and median ΔDNMT1 reduction 48 h after drug exposition was lower in DCT-resistant (-11.1%) than in DCT-sensitive (-50.5%, p = .030) cells. Rates of cell lines responsive to DCT exposition distinctly decreased to 25% after 72 h. No significant correlation of the patients´ age, sex, histological subtype, location of the paternal tumor, expression of Ki67, DNMT1 or the analyzed oncogenes with treatment response was found (p > .05, each). DCT efficacy was further independent of the methylation class and global DNA methylation of the paternal tumor. CONCLUSION: Early effects of DCT in meningiomas are strongly related with DNMT1 expression, while clinical, histological, and molecular predictors for efficacy are sparse. Kinetics of drug efficacy might indicate necessity of repeated exposition and encourage further analyses.

Confounders of intraoperative frozen section pathology during glioma surgery.

Although frozen section pathology (FSP) is commonly performed during surgery for glioma-suspicious lesions, confounders of accuracy are largely unknown. FSP and final diagnosis were compared in 398 surgeries for glioma-suspicious lesions. Diagnostic accuracy, risk factors for diagnostic shift from neoplastic to non-neoplastic tissue and vice versa according to the final diagnosis, and the impact on intraoperative and postoperative decision-making were analyzed. Diagnostic shift occurred in 70 cases (18%), and sensitivity, specificity, and the positive (PPV) and negative (NPV) predictive value of FSP were 82.5%, 77.8%, 99.4%, and 9.3%, respectively. No correlations between shift and patients' age and sex, sample fluorescence or volume, tumor location, correct information on the pathology form, final high- or low-grade histology, or molecular alterations were found (p > .05, each). Shift was more common after irradiation (25% vs 15%; p = .025) or chemotherapy (26% vs 15%; p = .022) than in treatment naïve cases and correlated with the type of surgery (p = .002). FSP altered intraoperative decision-making in 25 cases (6%). Postoperative shift led to repeated surgery in 12 patients (3%). In 45 cases, in which FSP and final diagnosis based on the same tissue, shift occurred in only 5 patients (11%), and sensitivity, specificity, PPV, and NPV for FSP were 77.4%, 78.6%, 88.9%, and 61.1%, respectively. No correlations between diagnostic shift and any of the analyzed variables were found (p > .05, each). Although accuracy of FSP during glioma surgery is sufficient, moderate NPV should be considered during intraoperative decision-making. While confounders are sparse, accuracy might be increased by repeated sampling. Diagnostic shift rarely alters postoperative treatment strategy.

Prognosis and histology of sporadic synchronous and metachronous meningiomas and comparative analyses with singular lesions.

Synchronous or metachronous growth of multiple tumors (≥ 2) is found in up to 20% of meningioma patients. However, biological as well as histological features and prognosis are largely unexplored. Clinical and histological characteristics were retrospectively investigated in 95 patients harboring 226 multiple meningiomas (MMs) and compared with 135 cases of singular meningiomas (SM) using uni- and multivariate analyses. In MM, tumors occurred synchronously and metachronously in 62% and 38%, respectively. WHO grade was intra-individually constant in all but two MMs, and histological subtype varied in 13% of grade 1 tumors. MM occurred more commonly in convexity/parasagittal locations, while SM were more frequent at the skull base (p < .001). In univariate analyses, gross total resection (p = .014) and high-grade histology in MM were associated with a prolonged time to progression (p < .001). Most clinical characteristics and rates of high-grade histology were similar in both groups (p ≥ .05, each). Multivariate analyses showed synchronous/metachronous meningioma growth (HR 4.50, 95% CI 2.26-8.96; p < .001) as an independent predictor for progression. Compared to SM, risk of progression was similar in cases with two (HR 1.56, 95% CI .76-3.19; p = .224), but exponentially raised in patients with 3-4 (HR 3.25, 1.22-1.62; p = .018) and ≥ 5 tumors (HR 13.80, 4.06-46.96; p < .001). Clinical and histological characteristics and risk factors for progression do not relevantly differ between SM and MM. Although largely constant, histology and WHO grade occasionally intra-individually vary in MM. A distinctly higher risk of disease progression in MM as compared to SM might reflect different underlying molecular alterations.

Iatrogenic lumbosacral infiltration with petroleum (hydrodesulfurized heavy) with secondary intrathecal distribution-a case report.

Petroleum is commonly used as a solvent, and primary intrathecal administration or secondary diffusion and subsequent clinical management has not been reported. We report the case of a male patient with intrathecal petroleum diffusion following accidental lumbar infiltration. After the onset of secondary myeloencephalopathy with coma and tetraparesis, continuous cranio-lumbar irrigation using an external ventricular and a lumbar drain was established. Cranial imaging revealed distinct supra- and infratentorial alterations. The patient improved slowly and was referred to rehabilitation. Intrathecal petroleum leads to myeloencephalopathy and continuous cranio-lumbar irrigation might be a safe treatment option.

Expression of decitabine-targeted oncogenes in meningiomas in vivo.

Treatment of meningiomas refractory to surgery and irradiation is challenging and effective chemotherapies are still lacking. Recently, in vitro analyses revealed decitabine (DCT, 5-aza-2'-deoxycytidine) to be effective in high-grade meningiomas and, moreover, to induce hypomethylation of distinct oncogenes only sparsely described in meningiomas in vivo yet.Expression of the corresponding onco- and tumor suppressor genes TRIM58, FAM84B, ELOVL2, MAL2, LMO3, and DIO3 were analyzed and scored by immunohistochemical staining and RT-PCR in samples of 111 meningioma patients. Correlations with clinical and histological variables and prognosis were analyzed in uni- and multivariate analyses.All analyzed oncogenes were highly expressed in meningiomas. Expression scores of TRIM58 tended to be higher in benign than in high-grade tumors 20 vs 16 (p = .002) and all 9 samples lacking TRIM58 expression displayed WHO grade II/III histology. In contrast, median expression scores for both FAM84B (6 vs 4, p ≤ .001) and ELOVL2 (9 vs 6, p < .001) were increased in high-grade as compared to benign meningiomas. DIO3 expression was distinctly higher in all analyzed samples as compared to the reference decitabine-resistant Ben-Men 1 cell line. Increased ELOVL2 expression (score ≥ 8) correlated with tumor relapse in both uni- (HR: 2.42, 95%CI 1.18-4.94; p = .015) and multivariate (HR: 2.09, 95%CI 1.01-4.44; p = .046) analyses.All oncogenes involved in DCT efficacy in vitro are also widely expressed in vivo, and expression is partially associated with histology and prognosis. These results strongly encourage further analyses of DCT efficiency in meningiomas in vitro and in situ.

The applicability of established clinical and histopathological risk factors for tumor recurrence during long-term postoperative care in meningioma patients.

Risk factors to predict late-onset tumor recurrence in meningioma patients are urgently needed to schedule control intervals during long-term follow-up. We therefore analyzed the value of established risk factors for postoperative meningioma recurrence for the prediction of long-term prognosis. Correlations of clinical and histopathological variables with tumor relapse after 3, 5, and 10 years following microsurgery were analyzed in uni- and multivariate analyses, and compared to findings in the entire cohort. In the entire cohort (N = 1218), skull base location (HR: 1.51, 95%CI 1.05-2.16; p = .026), Simpson ≥ IV resections (HR: 2.41, 95%CI 1.52-3.84; p < .001), high-grade histology (HR: 3.70, 95%CI 2.50-5.47; p < .001), and male gender (HR: 1.46, 95%CI 1.01-2.11; p = .042) were independent risk factors for recurrence. Skull base location (HR: 1.92, 95%CI 1.17-3.17; p = .010 and HR: 2.02, 95%CI 1.04-3.95; p = .038) and high-grade histology (HR: 1.87, 95%CI 1.04-3.38; p = .038 and HR: 2.29, 95%CI 1.07-4.01; p = .034) but not subtotal resection (HR: 1.53, 95%CI .68-3.45; p = .303 and HR: 1.75, 95%CI .52-5.96; p = .369) remained correlated with recurrence after a recurrence-free follow-up of ≥ 3 and ≥ 5 years, respectively. Postoperative tumor volume was related with recurrence in general (p < .001) but not beyond a follow-up of ≥ 3 years (p > .05). In 147 patients with a follow-up of ≥ 10 years, ten recurrences occurred and were not correlated with any of the analyzed variables. Skull base tumor location and high-grade histology but not the extent of resection should be considered when scheduling the long-term follow-up after meningioma surgery. Recurrences ≥ 10 years after surgery are rare, and predictors are lacking.

5-ALA kinetics in meningiomas: analysis of tumor fluorescence and PpIX metabolism in vitro and comparative analyses with high-grade gliomas.

INTRODUCTION: Although the utility 5-aminolevulinic acid (5-ALA)-mediated fluorescence-guided surgery (FGS) in meningiomas is increasingly discussed, data about the kinetics of protoporphyrin IX (PpIX) and tumor fluorescence are sparse. METHODS: PpIX kinetics after exposition to varying 5-ALA doses (12.5-150 µg/ml) was analyzed in two immortalized as well as primary WHO grade I and II meningioma and U87 high-grade glioma cell lines. Expression of FECH, ABCB6 and ABCG2 was investigated by quantitative real-time PCR. RESULTS: Fluorescence in Ben-Men 1 and primary WHO grade I/II meningioma increased with rising 5-ALA doses up to 100 µg/ml but then showed a saturation effect. However, decrease of fluorescence was slower after 150 than after 100 µg/ml 5-ALA. Fluorescence in U87 cells marginally increased with rising 5-ALA doses. Kinetics of the fluorescence in Ben-Men 1 cells did not differ from primary meningioma cells after 25-150 µg/ml 5-ALA (p > .05, each). No difference was found when comparing the fluorescence between primary grade I and II meningiomas after any 5-ALA dosage (p > .05, each). No relevant fluorescence was found in IOMM-Lee cells. Expression of FECH, ABCB6 and ABCG2 as well as PpIX export differed between all analyzed cell lines but were not connected to fluorescence. CONCLUSIONS: Eligibility of established meningioma cell lines for in-vitro analyzes of tumor fluorescence significantly differs. Fluorescence in Ben-Men 1 and primary meningioma cell lines but less in IOMM Lee cells is 5-ALA dose-dependent, encouraging in-situ trials to encounter currently discussed shortcomings of FGS in meningiomas. Fluorescence is not related to expression of FECH, ABCB6 and ABCG2.

The Simpson grading: defining the optimal threshold for gross total resection in meningioma surgery.

Classification of the extent of resection into gross and subtotal resection (GTR and STR) after meningioma surgery is derived from the Simpson grading. Although utilized to indicate adjuvant treatment or study inclusion, conflicting definitions of STR in terms of designation of Simpson grade III resections exist. Correlations of Simpson grading and dichotomized scales (Simpson grades I-II vs ≥ III and grade I-III vs ≥ IV) with postoperative recurrence/progression were compared using Cox regression models. Predictive values were further compared by time-dependent receiver operating curve (tdROC) analyses. In 939 patients (28% males, 72% females) harboring WHO grade I (88%) and II/III (12%) meningiomas, Simpson grade I, II, III, IV, and V resections were achieved in 29%, 48%, 11%, 11%, and < .5%, respectively. Recurrence/progression was observed in 112 individuals (12%) and correlated with Simpson grading (p = .003). The risk of recurrence/progression was increased after STR in both dichotomized scales but higher when subsuming Simpson grade ≥ IV than grade ≥ III resections (HR: 2.49, 95%CI 1.50-4.12; p < .001 vs HR: 1.67, 95%CI 1.12-2.50; p = .012). tdROC analyses showed moderate predictive values for the Simpson grading and significantly (p < .05) lower values for both dichotomized scales. AUC values differed less between the Simpson grading and the dichotomization into grade I-III vs ≥ IV than grade I-II vs ≥ III resections. Dichotomization of the extent of resection is associated with a loss of the prognostic value. The value for the prediction of progression/recurrence is higher when dichotomizing into Simpson grade I-III vs ≥ IV than into grade I-II vs ≥ III resections.

Predicting the risk of postoperative recurrence and high-grade histology in patients with intracranial meningiomas using routine preoperative MRI.

Risk factors for prediction of prognosis in meningiomas derivable from routine preoperative magnetic resonance imaging (pMRI) remain elusive. Correlations of tumor and edema volume, disruption of the arachnoid layer, heterogeneity of contrast enhancement, enhancement of the capsule, T2-intensity, tumor shape, and calcifications on pMRI with tumor recurrence and high-grade (WHO grade II/III) histology were analyzed in 565 patients who underwent surgery for WHO grade I (N = 516, 91%) or II/III (high-grade histology, N = 49, 9%) meningioma between 1991 and 2018. Edema volume (OR, 1.00; p = 0.003), heterogeneous contrast enhancement (OR, 3.10; p < 0.001), and an irregular shape (OR, 2.16; p = 0.015) were associated with high-grade histology. Multivariate analyses confirmed edema volume (OR, 1.00; p = 0.037) and heterogeneous contrast enhancement (OR, 2.51; p = 0.014) as risk factors for high-grade histology. Tumor volume (HR, 1.01; p = 0.045), disruption of the arachnoid layer (HR, 2.50; p = 0.003), heterogeneous contrast enhancement (HR, 2.05; p = 0.007), and an irregular tumor shape (HR, 2.57; p = 0.001) were correlated with recurrence. Multivariate analyses confirmed tumor volume (HR, 1.01; p = 0.032) and disruption of the arachnoid layer (HR, 2.44; p = 0.013) as risk factors for recurrence, independent of histology. Subgroup analyses revealed disruption of the arachnoid layer (HR, 9.41; p < 0.001) as a stronger risk factor for recurrence than high-grade histology (HR, 5.15; p = 0.001). Routine pMRI contains relevant information about the risk of recurrence or high-grade histology of meningioma patients. Loss of integrity of the arachnoid layer on MRI had a higher prognostic value than the WHO grading, and underlying histological or molecular alterations remain to be determined.

Telomerase activity, TERT expression, hTERT promoter alterations, and alternative lengthening of the telomeres (ALT) in meningiomas - a systematic review.

Telomerase activity and (human) Telomerase Reverse Transcriptase (hTERT) expression are considered hallmarks in oncogenesis of neoplasms and are upregulated by alterations of the hTERT promoter. In meningiomas, numerous studies investigated hTERT expression, telomerase activity, promoter mutations, and methylations. Moreover, reports about hTERT-targeted chemotherapy in meningiomas have recently been published. We provide a systematic review of the literature about the role of hTERT in meningiomas. TERT expression and telomerase activity is found in benign and high-grade meningiomas and increase with WHO grade. Remarkably, rates of TERT expression/telomerase activity usually exceed mutation frequency and both telomerase activity and TERT expression have also been found in hTERT promoter wildtype meningiomas, indicating further mechanisms of TERT upregulation. Although hTERT promoter methylation has been reported in the vast majority of meningiomas, correlation with TERT expression remains controversial. Rates of promoter mutations, and methylation were shown to increase with rising WHO grade. Moreover, promoter methylation and mutations strongly correlate with prognosis. Although mutations predicted malignant progression, de novo mutations in high-grade recurrences of former benign lesions were also observed. Retroviral transduction of the TERT gene enabled immortalization in several grade I-III meningioma cell lines. In vitro analyses revealed significant effects on viability in hTERT-mutated meningioma cells after targeted treatment. Alternative mechanisms of telomere lengthening are usually absent in meningiomas. TERT and hTERT promoter alterations play a major role during oncogenesis of meningiomas with implications for prognosis and potentially treatment.

Brain invasion in meningiomas: does surgical sampling impact specimen characteristics and histology?

Brain invasion (BI) is a new criterion for atypia in meningiomas and therefore potentially impacts adjuvant treatment. However, it remains unclear whether surgical practice and specimen characteristics influence histopathological analyses and the accuracy of detecting BI. Tumor location, specimen characteristics, and rates of BI were compared in meningioma samples obtained from 2938 surgeries in different neurosurgical departments but diagnosed in a single neuropathological institute. Non-skull base tumor location was associated with CNS tissue on the microscopic slides (OR 1.45; p < .001), increasing specimen weight (OR 1.01; p < .001), and remaining tissue not subjected to neuropathological analyses (OR 2.18; p < .001) but not with BI (OR 1.29; p = .199). Specimen weight, rates of residual tissue not subjected to histopathological analyses, of BI and of brain tissue, on the microscopic slides differed among the neurosurgical centers (p < .001, each). Frequency of BI was increased in one department (OR 2.07; p = .002) and tended to be lower in another (OR .61; p = .088). The same centers displayed the highest and lowest rates of brain tissue in the specimen, respectively (p < .001). Moreover, the correlation of BI with the neurosurgical center was not confirmed when only analyzing specimen with evidence of brain tissue in microscopic analyses (p = .223). Detection of BI was not correlated with the intraoperative use of CUSA in subgroup analyses. Rates of brain invasion in neuropathological analyses are not associated with tumor location but differ among some neurosurgical centers. Evidence raises that surgical nuances impact specimen characteristics and therefore the accuracy of the detection of BI.

Real-time in vivo kinetics of protoporphyrin IX after administration of 5-aminolevulinic acid in meningiomas and comparative analyses with glioblastomas.

BACKGROUND: The usefulness of 5-aminolevulinic acid (5-ALA)-mediated fluorescence-guided surgery (FGS) in meningiomas is intensely discussed. However, data about kinetics of 5-ALA and protoporphyrin (Pp) IX in meningiomas are lacking. METHODS: As the first study so far, we performed longitudinal intraoperative real-time ex situ measurements of fluorescence intensity and PpIX concentrations during FGS of ten benign and two atypical meningiomas. Kinetics were subsequently compared with data from 229 glioblastomas. RESULTS: Spectroscopy revealed fluorescence (median 2945.65 a.u.) and PpIX accumulation (median 18.31 µg/ml) in all 43 analyzed samples. Fluorescence intensity (2961.50 a.u. vs 118.41 a.u.; p < .001) and PpIX concentrations (18.72 µg/ml vs .98 µg/ml; p < .001) were higher in samples with (N = 30) than without (N = 2) visible intraoperative tumor fluorescence. ROC curve analyses revealed a PpIX cut-off concentration of 3.85 µg/ml (AUC = .992, p = .005) and a quantitative fluorescence cut-off intensity of 286.73 a.u. (AUC = .983, p = .006) for intraoperative visible tumor fluorescence. Neither fluorescence intensity (p = .356) nor PpIX (p = .631) differed between atypical and benign meningiomas. Fluorescence and PpIX peaked 7-8 h following administration of 5-ALA. Meningiomas displayed a higher fluorescence intensity (p = .012) and PpIX concentration (p = .005) than glioblastomas 5-6 h after administration of 5-ALA. Although fluorescence was basically maintained, PpIX appeared to be cleared faster in meningiomas than in glioblastomas. CONCLUSIONS: Kinetics of PpIX and fluorescence intensity differ between meningiomas and glioblastomas in the early phase after 5-ALA administration. Modification of the timing of drug administration might impact visibility of intraoperative fluorescence and helpfulness of FGS and should be investigated in future analyses.

Adverse events in brain tumor surgery: incidence, type, and impact on current quality metrics.

BACKGROUND: The aim of the study was to determine pre-operative factors associated with adverse events occurring within 30 days after neurosurgical tumor treatment in a German center, adjusting for their incidence in order to prospectively compare different centers. METHODS: Adult patients that were hospitalized due to a benign or malignant brain were retrospectively assessed for quality indicators and adverse events. Analyses were performed in order to determine risk factors for adverse events and reasons for readmission and reoperation. RESULTS: A total of 2511 cases were enrolled. The 30 days unplanned readmission rate to the same hospital was 5.7%. The main reason for readmission was tumor progression. Every 10th patient had an unplanned reoperation. The incidence of surgical revisions due to infections was 2.3%. Taking together all monitored adverse events, male patients had a higher risk for any of these complications (OR 1.236, 95%CI 1.025-1.490, p = 0.027). Age, sex, and histological diagnosis were predictors of experiencing any complication. Adjusted by incidence, the increased risk ratios greater than 10.0% were found for male sex, age, metastatic tumor, and hemiplegia for various quality indicators. CONCLUSIONS: We found that most predictors of outcome rates are based on preoperative underlying medical conditions and are not modifiable by the surgeon. Comparing our results to the literature, we conclude that differences in readmission and reoperation rates are strongly influenced by standards in decision making and that comparison of outcome rates between different health-care providers on an international basis is challenging. Each health-care system has to develop own metrics for risk adjustment that require regular reassessment.

Clinical, radiological, and histopathological predictors for long-term prognosis after surgery for atypical meningiomas.

BACKGROUND: Despite considerable rates of recurrence and mortality in atypical meningiomas, reliable predictors for estimating postoperative long-term prognosis remain elusive. METHODS: Clinical, histopathological, and radiological variables from 138 patients, including 64 females and 74 males (46% and 54%, median age 62 years), who underwent surgery for intracranial atypical meningioma were retrospectively analyzed. Associations between variables and recurrence and mortality were investigated using uni- and multivariate analyses. RESULTS: Gross total (GTR) and subtotal resection (STR) was achieved in 81% and 19% of cases, respectively. Within a median follow-up of 62 months, recurrence occurred in 52 (38%) and mortality in 22 (16%) cases. In patients who did not receive adjuvant irradiation, recurrence rates were higher after STR than after GTR (32% vs 63%, p = 0.025). In univariate analyses, only intratumoral calcifications on preoperative MRI (p = 0.012) and the presence of brain invasion in the absence of other histological grading criteria (p = 0.010) were correlated with longer progression-free intervals (PFI). In multivariate analyses, patient age was positively (HR 1.03, 95%CI 1.04-1.05; p = 0.018) and the presence of brain invasion as the only grading criterion (HR 0.37, 95%CI 0.19-0.74; p = 0.005) was negatively related with progression, while rising age at the time of surgery (HR 1.07, 95%CI 1.03-1.12; p = 0.001) was prognostic for mortality. CONCLUSIONS: PFI was longer in brain invasive but otherwise histological benign meningiomas and in tumors displaying calcifications on preoperative MRI. Advancing patient age and lower Karnofsky Performance Score were associated with higher overall mortality.

Anaplastic astrocytoma with piloid features, a novel molecular class of IDH wildtype glioma with recurrent MAPK pathway, CDKN2A/B and ATRX alterations.

Tumors with histological features of pilocytic astrocytoma (PA), but with increased mitotic activity and additional high-grade features (particularly microvascular proliferation and palisading necrosis) have often been designated anaplastic pilocytic astrocytomas. The status of these tumors as a separate entity has not yet been conclusively demonstrated and molecular features have only been partially characterized. We performed DNA methylation profiling of 102 histologically defined anaplastic pilocytic astrocytomas. T-distributed stochastic neighbor-embedding (t-SNE) and hierarchical clustering analysis of these 102 cases against 158 reference cases from 12 glioma reference classes revealed that a subset of 83 of these tumors share a common DNA methylation profile that is distinct from the reference classes. These 83 tumors were thus denominated DNA methylation class anaplastic astrocytoma with piloid features (MC AAP). The 19 remaining tumors were distributed amongst the reference classes, with additional testing confirming the molecular diagnosis in most cases. Median age of patients with MC AAP was 41.5 years. The most frequent localization was the posterior fossa (74%). Deletions of CDKN2A/B (66/83, 80%), MAPK pathway gene alterations (49/65, 75%, most frequently affecting NF1, followed by BRAF and FGFR1) and mutations of ATRX or loss of ATRX expression (33/74, 45%) were the most common molecular alterations. All tumors were IDH1/2 wildtype. The MGMT promoter was methylated in 38/83 tumors (45%). Outcome analysis confirmed an unfavorable clinical course in comparison to PA, but better than IDH wildtype glioblastoma. In conclusion, we show that a subset of histologically defined anaplastic pilocytic astrocytomas forms a separate DNA methylation cluster, harbors recurrent alterations in MAPK pathway genes in combination with alterations of CDKN2A/B and ATRX, affects patients who are on average older than those diagnosed with PA and has an intermediate clinical outcome.

Visualizing protoporphyrin IX formation in the dura tail of meningiomas by mass spectrometry imaging.

BACKGROUND: The advantages of 5-aminolevulinacid (5-ALA)-induced fluorescence-guided surgery in meningiomas are increasingly discussed. In this context, despite detectable tumor tissue in histopathologial analyses, no fluorescence was shown at the dura tail using the standard operating microscope. Thus, 5-ALA metabolism in this surgically important site remains unknown but needs to be elucidated when further evaluating indications of fluorescence-guided surgery in meningiomas. METHOD: We here present the spatially resolved identification of protoporphyrin IX (PpIX) in sphenoid ridge meningioma cryosections from a patient who underwent fluorescence-guided microsurgery using molecular imaging analysis by matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-MS/MS). RESULTS: Despite a strong fluorescence of the main tumor, no fluorescence could be detected at the dura tail using the standard operating microscope (blue-light, 405 nm). However, histopathological analyses clearly showed meningioma tissue. Remarkably, MALDI-MS/MS analysis revealed PpIX formation also at the non-fluorescing dura tail. However, no PpIX was detected in the tumor free dura mater. CONCLUSION: MALDI-MS/MS visualized a selective accumulation of PpIX within the tumor tissue including the dura tail. Thus, absence of fluorescence in the dura tail as visualized by the operating microscope is not caused by the lack of PpIX formation.

The evolution of cranial meningioma surgery-a single-center 25-year experience.

BACKGROUND: There have been major developments in diagnostic and surgical and non-surgical techniques used in the management of meningiomas over last three decades. We set out to describe these changes in a systematic manner. METHOD: Clinical and radiological data, surgical procedures, complications, and outcome of 817 patients who underwent surgery for primarily diagnosed meningioma between 1991 and 2015 were investigated. RESULTS: Median age at diagnosis increased significantly from 56 to 59 years (p = .042), while tumor location and preoperative Karnofsky performance status did not change during the observation period. Availability of preoperative MRI increased, and rates of angiography and tumor embolization decreased (p < .001, each). Median duration of total, pre-, and postoperative stay was 13, 2, and 9 days, respectively, and decreased between 1991 and 2015 (p < .001, each). Median incision-suture time varied annually (p < .001) but without becoming clearly longer or shorter during the entire observation period. The use of intraoperative neuronavigation and neuromonitoring increased, while the rates of Simpson grade I and III surgeries decreased (p < .001). Rates of postoperative hemorrhage (p = .997), hydrocephalus (p = .632), and wound infection (p = .126) did not change, while the frequency of early postoperative neurological deficits decreased from 21% between 1991 and 1995 to 13% between 2011 and 2015 (p = .003). During the same time, the rate of surgeries for postoperative cerebrospinal fluid leakage slightly increased from 2 to 3% (p = .049). Within a median follow-up of 62 months, progression was observed in 114 individuals (14%). Progression-free interval did not significantly change during observation period (p > .05). Multivariate analyses confirmed the lack of correlation between year of surgery and tumor relapse (HR: 1.1, p > .05). CONCLUSIONS: Preoperative diagnosis and surgery of meningiomas have been substantially evolved. Although early neurological outcome has improved, long-term prognosis remains unchanged.

The Simpson grading in meningioma surgery: does the tumor location influence the prognostic value?

In meningiomas, location-specific differences of the prognostic value of the Simpson classification are sparsely investigated but can influence strategy of surgery. We therefore compared the prognostic value of the Simpson classification in different tumor locations. Progression was compared with Simpson grade in 826 meningioma patients (median age 58 years, female:male ratio 2.4) in location-specific uni- and multivariate analyses. Simpson grade strongly correlated with tumor location (p < .001). Within a median follow-up of 50 months, recurrence was observed in 107 of 803 patients (13%). In general, increasing Simpson grade (p = .002) and subtotal resection (STR, ≥grade III) were correlated with tumor recurrence [hazard ratio (HR): 1.87; p = .004]. In 268 convexity meningiomas, frequency of tumor recurrence correlated with Simpson grade (p = .034). Risk of recurrence was similar after grade I and II resections, tended to increase after grade III (HR: 2.35; p = .087) but was higher after grade IV resections (HR: 7.35; p = .003). Risk of recurrence was higher after STR (HR: 4.21; p = .001) than after gross total resection (GTR, ≤grade II). Contrarily, increasing Simpson grade and STR were not correlated with progression in 102 falx, 38 posterior fossa and nine intraventricular meningiomas. In 325 skull base lesions, risk of recurrence was similar after GTR and STR (p = .198) and was only increased after grade IV resections (HR: 3.26; p = .017). Simpson grading and extent of resection were not equally prognostic in all locations. Lower impact of extent of resection should be considered during surgery for skull base, posterior fossa and falx meningiomas.