Meningiomas With Rhabdoid Features Lacking Other Histologic Features of Malignancy: A Study of 44 Cases and Review of the Literature

BAP1 mutations in high-grade meningioma: implications for patient care

We have recently shown that the breast cancer (BRCA)1-associated protein-1 tumor suppressor gene (BAP1) is inactivated in a subset of clinically aggressive meningiomas that display rhabdoid histomorphology. Immunohistochemistry for BAP1 protein provides a rapid and inexpensive method for screening suspected cases. Notably, some patients with BAP1-mutant meningiomas have germline BAP1 mutations and BAP1 tumor predisposition syndrome (TPDS). It appears that nearly all patients with germline BAP1 mutations develop malignancies by age 55, most frequently uveal melanoma, cutaneous melanoma, pleural or peritoneal malignant mesothelioma, or renal cell carcinoma, although other cancers have also been associated with BAP1 TPDS. Therefore, when confronted with a patient with a potentially high-grade rhabdoid meningioma, it is important that neuropathologists assess the BAP1 status of the tumor and that the patient's family history of cancer is carefully ascertained. In the appropriate clinical setting, genetic counseling and germline BAP1 DNA sequencing should be performed. A cancer surveillance program for individuals who carry germline BAP1 mutations may help identify tumors such as uveal melanoma, cutaneous melanoma, and renal cell carcinoma at early and treatable stages. Because BAP1-mutant meningiomas are rare tumors, multi-institutional efforts will be needed to evaluate therapeutic strategies and to further define the clinicopathologic features of these tumors.

Epithelial differentiation with microlumen formation in meningioma: diagnostic utility of NHERF1/EBP50 immunohistochemistry

Meningioma is a primary brain tumor arising from the neoplastic transformation of meningothelial cells. Several histological variants of meningioma have been described. Here we show that NHERF1/EBP50, an adaptor protein required for structuring specialized polarized epithelia, can distinguish meningioma variants with epithelial differentiation. NHERF1 decorates the membrane of intracytoplasmic lumens and microlumens in the secretory variant, consistent with a previously described epithelial differentiation of this subtype. NHERF1 also labels microlumens in chordoid meningioma, an epithelial variant not previously known to harbor these structures, and ultrastructural analysis confirmed the presence of microlumens in this variant. NHERF1 associates with the ezrin-radixin-moesin (ERM)-NF2 cytoskeletal proteins, and moesin but not NF2 was detectable in the microlumens. In a meningioma series from 83 patients, NHERF1 revealed microlumens in 87.5% of the chordoid meningioma (n = 25) and meningioma with chordoid component (n = 7) cases, and in 100% of the secretory meningioma cases (n = 12). The most common WHO grade I meningioma variants lacked microlumens. Interestingly, 20% and 66.6% of WHO grades II (n = 20) and III (n = 3) meningiomas, respectively, showed microlumen-like NHERF1 staining of ultrastructural tight microvillar interdigitations, mainly in rhabdoid, papillary-like or sheeting areas, revealing a new subset of high grade meningiomas with epithelial differentiation. NHERF1 failed to detect microlumens in 12 additional cases of chordoid glioma of the 3rd ventricle, chordoma and chondrosarcoma, neoplasms that may mimic the histological appearance of chordoid meningioma. This study uncovers features of epithelial differentiation in meningioma and proposes NHERF1 immunohistochemistry as a method of discriminating chordoid meningioma from neoplasms with similar appearance.

Advances in meningioma genetics: novel therapeutic opportunities

Meningiomas currently are among the most frequent intracranial tumours. Although the majority of meningiomas can be cured by surgical resection, ∼20% of patients have an aggressive clinical course with tumour recurrence or progressive disease, resulting in substantial morbidity and increased mortality of affected patients. During the past 3 years, exciting new data have been published that provide insights into the molecular background of meningiomas and link sites of tumour development with characteristic histopathological and molecular features, opening a new road to novel and promising treatment options for aggressive meningiomas. A growing number of the newly discovered recurrent mutations have been linked to a particular clinicopathological phenotype. Moreover, the updated WHO classification of brain tumours published in 2016 has incorporated some of these molecular findings, setting the stage for the improvement of future therapeutic efforts through the integration of essential molecular findings. Finally, an additional potential classification of meningiomas based on methylation profiling has been launched, which provides clues in the assessment of individual risk of meningioma recurrence. All of these developments are creating new prospects for effective molecularly driven diagnosis and therapy of meningiomas.

Germline and somatic BAP1 mutations in high-grade rhabdoid meningiomas

Background

Patients with meningiomas have widely divergent clinical courses. Some entirely recover following surgery alone, while others have relentless tumor recurrences. This clinical conundrum is exemplified by rhabdoid meningiomas, which are designated in the World Health Organization Classification of Tumours as high grade, despite only a subset following an aggressive clinical course. Patient management decisions are further exacerbated by high rates of interobserver variability, biased against missing possibly aggressive tumors. Objective molecular determinants are needed to guide classification and clinical decision making.

Methods

To define genomic aberrations of rhabdoid meningiomas, we performed sequencing of cancer-related genes in 27 meningiomas from 18 patients with rhabdoid features and evaluated breast cancer [BRCA]1-associated protein 1 (BAP1) expression by immunohistochemistry in 336 meningiomas. We assessed outcomes, germline status, and family history in patients with BAP1-negative rhabdoid meningiomas.

Results

The tumor suppressor gene BAP1, a ubiquitin carboxy-terminal hydrolase, is inactivated in a subset of high-grade rhabdoid meningiomas. Patients with BAP1-negative rhabdoid meningiomas had reduced time to recurrence compared with patients with BAP1-retained rhabdoid meningiomas (Kaplan-Meier analysis, 26 mo vs 116 mo, P < .001; hazard ratio 12.89). A subset of patients with BAP1-deficient rhabdoid meningiomas harbored germline BAP1 mutations, indicating that rhabdoid meningiomas can be a harbinger of the BAP1 cancer predisposition syndrome.

Conclusion

We define a subset of aggressive rhabdoid meningiomas that can be recognized using routine laboratory tests. We implicate ubiquitin deregulation in the pathogenesis of these high-grade malignancies. In addition, we show that familial and sporadic BAP1-mutated rhabdoid meningiomas are clinically aggressive, requiring intensive clinical management.

Rhabdoid Meningioma Arising Concurrent in Pulmonary and Intracranial with a Rare Malignant Clinical Progression: Case Report and Literature Review

BACKGROUND

Rhabdoid meningioma (RM) is an unusual variant of meningioma, classified as World Health Organization grade III. Although its recurrence is common, extracranial metastasis is rare and usually misdiagnosed. The transfer mechanism and pathway are ambiguous; once the metastasis occurs, the prognosis is poor, and there is no effective management. The present case is the first report of concurrent intracranial and pulmonary RM with rapid and widespread metastasis. We hope this report can serve as a helpful reference for clinicians and radiologists.

CASE DESCRIPTION

A 39-year-old woman presented to our hospital complaining of headache and memory disturbances. Magnetic resonance imaging (MRI) of the brain revealed a well-defined, inhomogeneous signal tumor with intense enhancement and severe peritumoral edema. Postoperatively, RM (grade III) was confirmed by histopathology. A chest CT performed 2 weeks later revealed an isolated lung mass, which was confirmed as RM on subsequent surgery. Three months after the first radiotherapy, the cancer had progressed uncommonly rapidly with widespread metastasis to the cerebellum, lung, kidney, and thigh. Gamma knife radiosurgery, chemotherapy, and molecular-targeted therapy were performed; however, the patient's condition continued to worsen, and she died 1 year after the initial operation.

CONCLUSIONS

Intracranial RM is a relatively rare tumor with the potential for wide intracranial and extracranial transfer. Cystic components and necrosis can be seen in this type of meningioma. Metastatic meningioma should be kept in mind when dealing with isolated lung lesions. This case report may serve as a helpful reference for clinicians and radiologists.

Development of an Atypical Teratoid Rhabdoid Tumor in a Meningioma

We describe an atypical teratoid rhabdoid tumor (AT/RT) with a component of low-grade and anaplastic rhabdoid meningioma in a 7-year-old child. The AT/RT was uniformly negative for INI1 and displayed immunoreactivity for vimentin, P53, CD99, cytokeratins with AE1/AE3 antibodies, epithelial membrane antigen, β-catenin, smooth muscle actin, E-cadherin, and S-100 protein. AT/RT was continuous, with small foci of recognizable low-grade and anaplastic meningioma. The low-grade meningioma was INI1 positive with scattered INI1-negative nuclei, whereas the remaining tumor components were INI1 negative. A recurrent tumor 6 months after partial resection contained only INI1-negative AT/RT. This case supports the hypothesis that rare examples of AT/RT may emerge from a preexisting “parent” neoplasm as a result of a second hit mutation.

Genomic landscape of high-grade meningiomas

High-grade meningiomas frequently recur and are associated with high rates of morbidity and mortality. To determine the factors that promote the development and evolution of these tumors, we analyzed the genomes of 134 high-grade meningiomas and compared this information with data from 587 previously published meningiomas. High-grade meningiomas had a higher mutation burden than low-grade meningiomas but did not harbor any statistically significant mutated genes aside from NF2. High-grade meningiomas also possessed significantly elevated rates of chromosomal gains and losses, especially among tumors with monosomy 22. Meningiomas previously treated with adjuvant radiation had significantly more copy number alterations than radiation-induced or radiation-naïve meningiomas. Across serial recurrences, genomic disruption preceded the emergence of nearly all mutations, remained largely uniform across time, and when present in low-grade meningiomas, correlated with subsequent progression to a higher grade. In contrast to the largely stable copy number alterations, mutations were strikingly heterogeneous across tumor recurrences, likely due to extensive geographic heterogeneity in the primary tumor. While high-grade meningiomas harbored significantly fewer overtly targetable alterations than low-grade meningiomas, they contained numerous mutations that are predicted to be neoantigens, suggesting that immunologic targeting may be of therapeutic value.

DNA methylation-based classification and grading system for meningioma: a multicentre, retrospective analysis

BACKGROUND

The WHO classification of brain tumours describes 15 subtypes of meningioma. Nine of these subtypes are allotted to WHO grade I, and three each to grade II and grade III. Grading is based solely on histology, with an absence of molecular markers. Although the existing classification and grading approach is of prognostic value, it harbours shortcomings such as ill-defined parameters for subtypes and grading criteria prone to arbitrary judgment. In this study, we aimed for a comprehensive characterisation of the entire molecular genetic landscape of meningioma to identify biologically and clinically relevant subgroups.

METHODS

In this multicentre, retrospective analysis, we investigated genome-wide DNA methylation patterns of meningiomas from ten European academic neuro-oncology centres to identify distinct methylation classes of meningiomas. The methylation classes were further characterised by DNA copy number analysis, mutational profiling, and RNA sequencing. Methylation classes were analysed for progression-free survival outcomes by the Kaplan-Meier method. The DNA methylation-based and WHO classification schema were compared using the Brier prediction score, analysed in an independent cohort with WHO grading, progression-free survival, and disease-specific survival data available, collected at the Medical University Vienna (Vienna, Austria), assessing methylation patterns with an alternative methylation chip.

FINDINGS

We retrospectively collected 497 meningiomas along with 309 samples of other extra-axial skull tumours that might histologically mimic meningioma variants. Unsupervised clustering of DNA methylation data clearly segregated all meningiomas from other skull tumours. We generated genome-wide DNA methylation profiles from all 497 meningioma samples. DNA methylation profiling distinguished six distinct clinically relevant methylation classes associated with typical mutational, cytogenetic, and gene expression patterns. Compared with WHO grading, classification by individual and combined methylation classes more accurately identifies patients at high risk of disease progression in tumours with WHO grade I histology, and patients at lower risk of recurrence among WHO grade II tumours (p=0·0096) from the Brier prediction test). We validated this finding in our independent cohort of 140 patients with meningioma.

INTERPRETATION

DNA methylation-based meningioma classification captures clinically more homogenous groups and has a higher power for predicting tumour recurrence and prognosis than the WHO classification. The approach presented here is potentially very useful for stratifying meningioma patients to observation-only or adjuvant treatment groups. We consider methylation-based tumour classification highly relevant for the future diagnosis and treatment of meningioma.

FUNDING

German Cancer Aid, Else Kröner-Fresenius Foundation, and DKFZ/Heidelberg Institute of Personalized Oncology/Precision Oncology Program.