Meningeal Solitary Fibrous Tumor Research Articles

NAB2::STAT6 fusions and genome-wide DNA methylation profiling: Predictors of patient outcomes in meningeal solitary fibrous tumors.

Meningeal solitary fibrous tumors (SFT) are rare and have a high frequency of local recurrence and distant metastasis. In a cohort of 126 patients (57 female, 69 male; mean age at surgery 53.0 years) with pathologically confirmed meningeal SFTs with extended clinical follow-up (median 9.9 years; range 15 days-43 years), we performed extensive molecular characterization including genome-wide DNA methylation profiling (n = 80) and targeted TERT promoter mutation testing (n = 98). Associations were examined with NAB2::STAT6 fusion status (n = 101 cases; 51 = ex5-7::ex16-17, 26 = ex4::ex2-3; 12 = ex2-3::exANY/other and 12 = no fusion) and placed in the context of 2021 Central Nervous System (CNS) WHO grade. NAB2::STAT6 fusion breakpoints (fusion type) were significantly associated with metastasis-free survival (MFS) (p = 0.03) and, on multivariate analysis, disease-specific survival (DSS) when adjusting for CNS WHO grade (p = 0.03). DNA methylation profiling revealed three distinct clusters: Cluster 1 (n = 38), Cluster 2 (n = 22), and Cluster 3 (n = 20). Methylation clusters were significantly associated with fusion type (p < 0.001), with Cluster 2 harboring ex4::ex2-3 fusion in 16 (of 20; 80.0%), nearly all TERT promoter mutations (7 of 8; 87.5%), and predominantly an "SFT" histologic phenotype (15 of 22; 68.2%). Clusters 1 and 3 were less distinct, both dominated by tumors having ex5-7::ex16-17 fusion (respectively, 25 of 33; 75.8%, and 12 of 18; 66.7%) and with variable histological phenotypes. Methylation clusters were significantly associated with MFS (p = 0.027), but not overall survival (OS). In summary, NAB2::STAT6 fusion type was significantly associated with MFS and DSS, suggesting that tumors with an ex5::ex16-17 fusion may have inferior patient outcomes. Methylation clusters were significantly associated with fusion type, TERT promoter mutation status, histologic phenotype, and MFS.

Meningeal Solitary Fibrous Tumor: A Single-Center Retrospective Cohort Study.

Meningeal solitary fibrous tumors (SFTs) are rare, malignant, mesenchymal tumors of the central nervous system. While surgical gross total resection is widely accepted as a positive prognostic factor for local control (LC), the role of postoperative radiotherapy (PORT) remains controversial. We sought to report our institutional experience with a particular focus on outcomes after PORT. In this single-center, retrospective cohort study, 20 patients with the primary diagnosis of histopathologically confirmed meningeal SFT were analyzed. Data on patient characteristics, imaging, treatment modalities, histopathology, and oncological outcomes were collected. LC and overall survival (OS) were assessed using the Kaplan-Meier estimator. The median follow-up time was 95.8 months. After surgery only, 9 out of 11 patients (81.8%) developed a local recurrence while, after surgery and PORT, 3 out of 9 patients (33.33%) showed local failure. The 5- and 10-year LC rates were 50.5% and 40.4% in the surgery-only group and 80% at both time points in the surgery with the PORT group. In the surgery-only group, 4 out of 11 patients (36.4%) died, and 4 out of 9 patients (44.4%) died in the surgery and PORT group. OS rates after 5 and 10 years were 88.9% and 66.7% in the surgery-only group and 88.9% and 76.2% in the surgery with PORT group. Our findings suggest that PORT may improve LC in patients with meningeal SFT. The low incidence of meningeal SFT impedes prospective studies and requires further international collaborative efforts to exploit retrospective datasets and molecular analysis to improve patient outcomes.

NIMG-78. USE OF ARTERIAL SPIN LABELING TO DETECT METASTASIS OF MENINGEAL SOLITARY FIBROUS TUMORS

Abstract Meningeal solitary fibrous tumors (SFT), formerly known as hemangiopericytoma, are rare, highly vascular, mesenchymal dural based neoplasms. Meningeal SFT require lifelong imaging surveillance given high risk of recurrence and metastasis, even decades after initial diagnosis. Often these metastases are initially small, nodular dural masses that are difficult to detect with standard brain tumor imaging protocols. Given SFT are highly vascular tumors, we hypothesized that recurrent meningeal SFT would have elevated cerebral blood flow using Arterial Spin Labeling (ASL) perfusion imaging. ASL is a noninvasive MRI technique used to detect cerebral blood flow in high grade neoplasms and hyper vascular meningiomas without intravenous contrast. We evaluated ASL in two patients with recurrent meningeal SFT. In both patients the recurrent meningeal SFT demonstrated elevated perfusion by ASL. In one patient, the elevated ASL signature enabled identification of a small metastasis that was not initially appreciated on structural imaging. Following treatment with antiangiogenic therapy, ASL was no longer elevated while enhancement did not change. To our knowledge, this is the first study reporting utility of ASL imaging in detecting intracranial recurrence of meningeal SFT. We propose further study of sensitivity of ASL to detect recurrent meningeal SFT.

EPCO-48. THE SINGLE-CELL AND SPATIAL TRANSCRIPTOMIC ARCHITECTURE OF MENINGEAL SOLITARY FIBROUS TUMORS PHENOCOPIES CEREBRAL VASCULAR DEVELOPMENT AND HOMEOSTASIS

Abstract INTRODUCTION Meningeal solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms that are associated with local recurrence and distant metastasis. The cell states and spatial transcriptomic architecture of SFTs are unknown. METHODS Single-cell RNA sequencing or spatial transcriptomic sequencing were performed on 40,022 cells or 23,682 spatial transcriptomes from 12 meningeal SFT samples. Datasets were corrected for batch effects using Harmony and integrated using uniform maniform approximation and projection (UMAP). Clusters were defined using automated cell type classification, cell signature gene sets, cell cycle analysis, and differentially expressed marker genes. Trajectory analyses were performed using RNA velocity and pseudotime. Cell-cell communication analysis was performed using CellChat. RESULTS were validated using immunofluorescence and immunohistochemistry and generalized using comparisons to 30,934 single-cell transcriptomes from 6 meningioma samples, 139,134 perinatal human brain vascular single-cell transcriptomes, 84,138 adult human brain vascular single-cell transcriptomes, and DNA methylation profiles from 8 SFT and 221 meningioma samples. RESULTS Unsupervised hierarchical clustering of DNA methylation profiles revealed molecular distinction of meningeal SFTs from meningiomas. Deconvolution of vascular single-cell types showed SFT cell clusters resembling perinatal or adult fibroblasts, perinatal mitotic endothelia, and adult venous or arterial endothelia. UMAP and trajectory analyses showed SFTs were comprised of 8 interchangeable tumor cell states that were associated with cell adhesion (VCAM1, NCAM2), cell stress (EGR1), cell signaling (NOTCH3), extracellular matrix remodeling (ECM) (ADAMTS6, PLCG2), or protein synthesis pathways (RPL27A, RPL37). Cell-cell communication analyses identified single-cell and spatial interactions between VCAM1- or NCAM2-expressing SFT cells and endothelia or immature neurons in the tumor microenvironment, respectively. Single-cell deconvolution demonstrated evolution of ECM and protein synthesis SFT cells in paired primary/recurrent samples, and evolution of ECM SFT cells and macrophages in paired primary/metastatic samples. CONCLUSIONS The single-cell and spatial transcriptomic architecture of meningeal SFT reveals dynamic cell states that phenocopy cerebral vascular development and homeostasis.

The Role of Immunotherapy in the Treatment of Rare Central Nervous System Tumors.

Establishing novel therapies for rare central nervous system (CNS) tumors is arduous due to challenges in conducting clinical trials in rare tumors. Immunotherapy treatment has been a rapidly developing field and has demonstrated improvements in outcomes for multiple types of solid malignancies. In rare CNS tumors, the role of immunotherapy is being explored. In this article, we review the preclinical and clinical data of various immunotherapy modalities in select rare CNS tumors, including atypical meningioma, aggressive pituitary adenoma, pituitary carcinoma, ependymoma, embryonal tumor, atypical teratoid/rhabdoid tumor, and meningeal solitary fibrous tumor. Among these tumor types, some studies have shown promise; however, ongoing clinical trials will be critical for defining and optimizing the role of immunotherapy for these patients.

Expression of neuroendocrine markers in meningeal and extrameningeal solitary fibrous tumors: a potential diagnostic pitfall

Solitary fibrous tumors (SFTs) may show unusual morphologies, and in such circumstances, an unexpected immunoprofile can be misleading. Following an index case of myxoid meningeal SFT with a neuroendocrine immunoprofile, we decided to assess a neuroendocrine profile in SFTs from various locations. The cohort of 9 meningeal and 28 extrameningeal SFTs was evaluated for CNS WHO grade (G1-G3) and 4-tiered Demicco risk stratification. Immunohistochemical detection of synaptophysin, chromogranin, INSM1, CD56, and CD57 was performed in each case and semiquantitatively assessed (0: no expression; 1+: <10% positive; 2+: 11-50%; and 3+: >51%); whole sections (meningeal SFTs) or tissue microarray (extrameningeal SFTs) were used for immunohistochemistry. The cohort included 13 men and 24 women. Meningeal SFTs included 5 WHO G1, 3 WHO G2, and 1 WHO G3 tumors. Extrameningeal SFTs included 21 low-risk, 4 intermediate-risk, and 2 high-risk tumors. INSM1 immunoreactivity was observed in 12 of 37 cases (32%; 8 cases 1+, 3 cases 2+, and 1 case 3+); synaptophysin was positive in 6 of 35 cases (19%; 5 cases 1+ and 1 case 2+); CD56 was positive in 20 of 37 cases (54%; 16 cases 1+, 3 cases 2+, and 1 case 3+); and CD57 was expressed in 14 of 36 cases (39%; 5 cases 1+, 4 cases 2+, and 5 cases 3+). Chromogranin positivity was not observed. No significant association was observed between expression of neuroendocrine markers and tumor grade, Demicco risk group or meningeal and extrameningeal location. Extrapleural SFTs showed a tendency for positivity of INSM1 (P=.014, χ2) and CD57 (P=.017, χ2)compared to pleural SFTs.

SIGNIFICANTLY STRONG EXPRESSION OF STAT6 AND SSTR2A IN DIFFERENTIATE THE SOLITARY FIBROUS TUMOR / HEMANGIOPERICYTOMA (SFT/HPC) AND MENINGIOMA

Background: Solitary fibrous tumor / hemangiopericytoma (SFT / HPC) and fibroblastic types of meningioma have similarities that is difficult to distinguish based on histology. Immunohistochemistry of STAT6 and SSTR2A are definitive biomarkers in both tumors. Inversion-mediated fusions between two genes, NAB2 and STAT6, were detected in SFT / HPC that inducES proliferation in cells. The somatostatin receptor (SSTR) 2 is located on chromosome 17q25.1 which is expressed diffusely in meningiomas.&#x0D; Objective: This study aimed to determine the expression of STAT6 and SSTR2A in SFT/HPC and meningiomas.&#x0D; Methods: An analytical observational study with consecutive sampling on 64 samples diagnosed with SFT/HPC and meningioma. Samples divided into 3 groups, group 1 consisted of grade I meningoma, group 2 consisted of grade II and III meningioma and group 3 consisted of solitary fibrous tumor/Hemangiopericytoma (SFT/HPC).&#x0D; Results: Based on the Mann Withney comparative test, STAT6 expressions showed significant differences in group 1 and 3, as well as group 2 and 3 (P &lt; 0.05). SSTR2A expressions in group 1 and 3, as well as group 2 and 3 also showed significant differences (P &lt; 0.05).&#x0D; Conclusion: Immunohistochemistry of STAT6 and SSTR2A is strongly expressed in SFT/HPC and meningioma.&#x0D; Keywords: Meningeal solitary fibrous tumor (SFT)/hemangiopericytoma (HPC), Meningioma, STAT6, SSTR2A.

Analysis of clinicopathological features and NAB2-STAT6 fusion variants of meningeal solitary fibrous tumor with ectopic salivary gland components in the cerebellopontine angle.

Solitary fibrous tumors (SFTs) are rare mesenchymal tumors that can occur at any location. Since the identification of specific NAB2-STAT6 fusion in SFTs, the fusion gene variants, NAB2 exon 4-STAT6 exon 2/3 and NAB2 exon 5/6/7-STAT6 exon 16/17/18, have been reported to be associated with clinicopathological features, and the latter variant is predominant in meningeal SFTs. SFTs developing in the salivary glands are rare, and more rarely, those involving ectopic salivary glands (ESGs) have been reported in the cerebellopontine angle (CPA); however, their characteristics remain not well understood. In this study, we performed a clinicopathological and molecular analysis of 3 cases of meningeal SFT with ESGs. All cases presented with an extra-axial mass in the CPA, which is a rarer location for intracranial ESGs compared to the sellar region. Histologically, except for the presence of ESGs, there was no significant difference between current cases and ordinary SFTs. The ESGs demonstrated no cellular atypia, and although the spindle tumor cells were immunopositive for STAT6, the ESGs were negative in all cases, supporting that the ESGs are non-neoplastic components. In 1 case, ESGs were found only in the primary tumor and disappeared in recurrence/dissemination. Of note, molecular analysis identified NAB2 exon 4-STAT6 exon 2 in all cases. In conclusion, our results suggest that ESGs particularly in the CPA may be associated with SFTs and that meningeal SFTs with ESGs may be associated with the minor fusion variant of NAB2-STAT6 in the intracranial lesions.

Positron emission tomography combined with computed tomography with &lt;sup&gt;18&lt;/sup&gt;F-fluorodeoxyglucose and &lt;sup&gt;18&lt;/sup&gt;F-сholine in meningeal solitary fibrous tumors: short literature review sample and clinical cases

Solitary fibrous tumors of the cerebral membranes are rare brain tumors. meningeal solitary fibrous tumors often metastasize outside the central nervous system, which significantly reduces the life expectancy of patients, while metastases can appear in a distant period after radical treatment of the primary intracranial tumor. The results of positron emission tomography combined with computed tomography with 18F-fluorodeoxyglucose and 18F-choline in 2 patients with different differentiation of solitary fibrous tumors were analyzed. The presented clinical cases demonstrate that clinical morphological variants of solitary fibrous tumors differ in aggressiveness and clinical course of the disease.

Peritorcular Meningeal Solitary Fibrous Tumor: A Case report

OBJECTIVE: In order to contribute to the Latin American epidemiology of these tumors, we present a Colombian case of a peritorcular meningeal solitary fibrous tumor (mSFT), demonstrating the histological findings, surgical nuances, and relevant anatomy for surgical resection. CASE REPORT: A 47-year-old Hispanic woman presented to the emergency department with a 1-month history of severe headache that was unresponsive to medication. Magnetic resonance imaging demonstrated a 4 x 4 x 4.7 cm hypointense lesion in the left occipital region with peritumoral edema, with homogeneous enhancement after gadolinium administration. Gross total resection was performed through a right occipital parasagittal craniotomy with a straightforward approach. Pathology examination reported the proliferation of spindle cells with diffuse and intense positive nuclear STAT6 staining, confirming the histological diagnosis of a mSTF. CONCLUSIONS: We present to our knowledge the first Colombian mSTF in the English literature, contributing to the epidemiology and presentation of this rare tumor in Latin America.

Case Report of a Rare Intracranial Tumour

A meningeal Solitary Fibrous Tumour (SFT), also called hemangiopericytoma is a fibroblastic type of mesenchymal tumour. These tumours often show a rich, well-branched vascular pattern that encompasses a histological spectrum of tumours which was previously classified separately as meningeal SFT and haemangiopericytoma. Discovery of NAB2-STAT6 fusion in a vast majority of haemangiopericytomas and solitary fibrous tumours indicates a possibility of morphological continuum. Herein, authors report a case 65-year-old female known case of hypertension and type II diabetes mellitus, presented with complaint of headache since 2 months and left side weakness since 3 weeks. On clinical examination, she was found to have motor weakness of left upper limb and lower limb with no sensory deficit. Magnetic resonance imaging showed an extra axial, right frontoparietal convexity, solidly enhancing tumour with transosseous invasion and the imaging features were suggestive of atypical meningioma. After craniotomy, immunohistochemical evaluation showed tumour cells were strongly positive for CD34 and STAT-6 exhibited the characteristic nuclear localization.The case was reported as Solitary fibrous tumour/Haemangiopericytoma-Grade II. The patient was advised adjuvant radiotherapy but deferred treatment. Regular follow-up after 2 years post surgery has shown that the patient is disease free.

Letter: Sacroplasty Augmentation of Instrumented Pelvic Reconstruction After High Sacrectomy: A Technical Case Report.

Letter: Sacroplasty Augmentation of Instrumented Pelvic Reconstruction After High Sacrectomy: A Technical Case Report.

Molecular description of meningeal solitary fibrous tumors/hemangiopericytomas compared to meningiomas: two completely separate entities.

Meningeal solitary fibrous tumors (SFT), like all SFT, are defined by NAB2-STAT6 fusion and share clinicopathologic similarities with meningiomas, the most frequent meningeal tumors. Our aim is to establish the molecular identity of meningeal SFT and seek molecular prognostic factors. RNA sequencing and whole exome sequencing were performed in STAT6-positive SFT and grade 2-3 meningiomas, and data concerning other soft tissues tumors was obtained from the local database. Uniform manifold approximation and projection, individual gene expression and Gene Set Enrichment Analysis were performed. RNA clustering shows that SFT share a common molecular signature, different from any other type of tumoral tissue. Meningeal SFT aggregate with other SFT, with no clinical or histological subgroup. Comparison of genes expressions suggests significant over-expressions of ZIC2, ZIC3, ZIC5, GABBR2, TP53 in CNS-SFT. The pathogenic TP53 c.743G>T variant, previously undescribed in SFT, was found in one sample of meningeal SFT during malignant progression. Meningeal SFT are molecular counterparts of extra-meningeal SFT, completely separate from meningiomas. They might develop from the same tissues and benefit from the same treatments as SFT.

Aberrant expression of thyroid transcription factor-1 in meningeal solitary fibrous tumor/hemangiopericytoma.

Meningeal solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) were categorized as the same entity in the World Health Organization (WHO) 2016 classification of tumors of the central nervous system (CNS). Although NAB2-STAT6 fusion protein can be used to distinguish most of SFT/HPC from the other sarcomas, additional biomarkers were requested to separate meningeal SFT/HPC from meningioma and the molecular pathological difference between meningeal SFT/HPC and extra-CNS SFT/HPC still remains unclear. In this study, we evaluated the expression of TTF-1 in 67 meningeal SFT/HPC, 62 extra-CNS SFT/HPC and 201 meningiomas samples with immunohistochemistry (IHC) assays. The results showed that TTF-1 was detected in 23 of 67 (34.3%) meningeal SFT/HPC, 3 retroperitoneum SFT/HPC and none of meningiomas. Meanwhile, the copy number variation and mRNA expression of TTF-1 were measured by real-time quantitative PCR (qPCR) in meningeal SFT/HPC. These results demonstrated that TTF-1 protein expression level was significantly correlated with its transcription level, but independently related to the gene copy number variant. In conclusion, our study suggested that a large proportion of meningeal SFT/HPC was positive to TTF-1, while very few extra CNS SFT/HPC cases and no meningiomas were stained. So TTF-1 has value as an auxiliary diagnostic marker for meningeal SFT/HPC.

Management of meningeal solitary fibrous tumors/hemangiopericytoma; surgery alone or surgery plus postoperative radiotherapy?

Introduction A meningeal solitary fibrous tumor (SFT), also called hemangiopericytoma, is a rare mesenchymal malignancy. Due to anatomic constrains, even after macroscopic complete surgery with curative intent, the local relapse risk is still relatively high, thus increasing the risk of dedifferentiation and metastatic spread. This study aims to better define the role of postoperative radiotherapy (RT) in meningeal SFTs. Patients and methods A retrospective study was performed across seven sarcoma centers. Clinical information was retrieved from all adult patients with meningeal primary localized SFT treated between 1990 and 2018 with surgery alone (S) compared to those that also received postoperative RT (S + RT). Differences in treatment characteristics between subgroups were tested using independent samples t-test for continuous variables and chi-square tests for proportions. Local control (LC) and overall survival (OS) rates were calculated as time from start of treatment until progression or death from any cause. LC and OS in groups receiving S or S + RT were compared using Kaplan–Meier survival curves. Results Among a total of 48 patients, 7 (15%) underwent S and 41 (85%) underwent S + RT. Median FU was 65 months. LC was significantly associated with treatment. LC after S at 60 months was 60% versus 90% after S + RT (p = 0.052). Furthermore, R1 resection status was significantly associated with worse LC (HR 4.08, p = 0.038). OS was predominantly associated with the mitotic count (HR 3.10, p = 0.011). Conclusion This retrospective study, investigating postoperative RT in primary localized meningeal SFT patients, suggests that combining RT to surgery in the management of this patient population may reduce the risk for local failures.

The impact of histopathology and NAB2\u2013STAT6 fusion subtype in classification and grading of meningeal solitary fibrous tumor/hemangiopericytoma

Meningeal solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) is a rare tumor with propensity for recurrence and metastasis. Although multiple classification schemes have been proposed, optimal risk stratification remains unclear, and the prognostic impact of fusion status is uncertain. We compared the 2016 WHO CNS tumor grading scheme (CNS-G), a three-tier system based on histopathologic phenotype and mitotic count, to the 2013 WHO soft-tissue counterpart (ST-G), a two-tier system based on mitotic count alone, in a cohort of 133 patients [59 female, 74 male; mean age 54 years (range 20–87)] with meningeal SFT/HPC. Tumors were pathologically confirmed through review of the first tumor resection (n = 97), local recurrence (n = 35), or distant metastasis (n = 1). A STAT6 immunostain showed nuclear expression in 132 cases. NAB2–STAT6 fusion was detected in 99 of 111 successfully tested tumors (89%) including the single STAT6 immunonegative tumor. Tumors were classified by CNS-G as grade 1 (n = 43), 2 (n = 41), or 3 (n = 49), and by ST-G as SFT (n = 84) or malignant SFT (n = 49). Necrosis was present in 16 cases (12%). On follow-up, 42 patients had at least one subsequent recurrence or metastasis (7 metastasis only, 33 recurrence only, 2 patients had both). Twenty-nine patients died. On univariate analysis, necrosis (p = 0.002), CNS-G (p = 0.01), and ST-G (p = 0.004) were associated with recurrence-free (RFS) but not overall survival (OS). NAB2–STAT6 fusion type was not significantly associated with RFS or OS, but was associated with phenotype. A modified ST-G incorporating necrosis showed higher correlation with RFS (p = 0.0006) and remained significant (p = 0.02) when considering only the primary tumors. From our data, mitotic rate and necrosis appear to stratify this family of tumors most accurately and could be incorporated in a future grading scheme.

Cytological characteristics of meningeal solitary fibrous tumor metastatic to the lung: A case report with immunocytochemical analysis.

Solitary fibrous tumor (SFT) is a relatively uncommon mesenchymal tumor, and its occurrence in the meninges is rare. We herein report what is, to the best of our knowledge, the first cytological case of meningeal SFT metastatic to the lung with immunocytochemical analysis for signal transducer and activator of transcription 6 (STAT6), and compare the cytological characteristics to those of pleuropulmonary SFT. A 58-year-old Japanese male patient was found to have multiple nodules in the bilateral lungs after surgery for meningeal SFT. Partial resection of the nodules was performed, and touch smears were obtained. The Papanicolaou smear revealed cohesive hypercellular clusters of polygonal to elongated neoplastic cells with scant cytoplasm and oval to short spindle-shaped nuclei with nucleoli containing coarse chromatin. Mild-to-moderate nuclear pleomorphism was observed. No collagenous stroma was noted. Immunocytochemical analysis revealed that the neoplastic cells diffusely expressed STAT6. Histopathological and immunohistochemical studies confirmed the diagnosis of meningeal SFT metastatic to the lung. Moreover, reverse transcription-polymerase chain reaction analysis revealed that the lung tumor harbored NAB2ex6-STAT6ex16 fusion. Recent studies demonstrated that there is a clinicopathological difference among NAB2-STAT6 fusion variants in SFT. As reflected in fusion variants, meningeal SFT occasionally lacks collagenous stroma, as in the present case, although the most characteristic cytological feature of SFT is the presence of spindle-shaped neoplastic cells embedded in dense collagenous stroma. Thus, immunocytochemical analysis for STAT6 is very useful for diagnosing SFT.

Grading of meningeal solitary fibrous tumors/hemangiopericytomas: analysis of the prognostic value of the Marseille Grading System in a cohort of 132 patients

The finding that meningeal solitary fibrous tumors (SFTs) and meningeal hemangiopericytomas (HPCs) are both characterized by NAB2-STAT6 gene fusion has pushed their inclusion in the WHO 2016 Classification of tumors of the central nervous system (CNS) as different manifestations of the same entity. Given that the clinical behavior of the CNS SFT/HPC spectrum ranges from benign to malignant, it is presently unclear whether the grading criteria are still adequate. Here, we present the results of a study that analyzed the prognostic value of an updated version of the Marseille Grading System (MGS) in a retrospectively assembled cohort of 132 primary meningeal SFTs/HPCs with nuclear overexpression of STAT6. The median patient follow-up was 64 months (range 4-274 months); 73 cases (55%) were MGS I, 50 cases (38%) MGS II and 9 cases (7%) were MGS III. Progression-free survival (PFS) and disease-specific survival (DSS) were investigated using univariate analysis: the prognostic factors for PFS included MGS, extent of surgery, radiotherapy, chemotherapy and mitotic activity ≥5/10 high-power field (HPF). Moreover, MGS, radiotherapy, mitotic activity ≥5/10 HPF, and necrosis were the prognostic factors measured for DSS. In multivariate analysis, extent of surgery, mitotic activity ≥5/10 HPF, MGS I and MGS III were the independent prognostic factors measured for PFS while necrosis, MGS III and radiotherapy were the independent prognostic factors for DSS. In conclusion, our results show that assessing the malignancy risk of SFT/HPC should not rely on one single criterion like mitotic activity. Therefore, MGS is useful as it combines the value of different criteria. In particular, the combination of a high mitotic activity and necrosis (MGS III) indicates a particularly poor prognosis.

Magnetic resonance features of meningeal solitary fibrous tumors.

The aim of the present study was to investigate magnetic resonance (MR) features of meningeal solitary fibrous tumors (SFTs) in order to improve their recognition. The study retrospectively analyzed MR manifestations in 12 cases of meningeal SFTs confirmed by surgery. The lesions were analyzed in terms of the site of their growth, growth mode, morphology, size, changes in the MR signal and the edge of the focus. The tumors were malignant in 3 cases, benign in 7 cases and borderline in 2 cases. A total of 3 cases spanned the tentorium cerebelli, 3 spanned the falx and another case was close to the falx. Overall, 4 superficial tumors were accompanied by adjacent bony destruction. One case was located at the triangular area created by the right lateral ventricles. The tumors were all lobular, with a large diameter and more cystic areas in the center of the focus. The signals were often heterogeneous. The parenchyma in the tumors was significantly enhanced. For certain tumors, the signal was usually inhomogeneous and not uniform. The MR features of a SFT were often similar to other intracranial tumors and easily misdiagnosed. There were certain innate characteristics, for example, the tumor was often a solitary large soft-tissue mass with an irregular edge and a clear boundary, with a lobulated contour, and was widely involved with other tissues. The tumors often grew across either the falx or tentorium cerebelli. A significantly inhomogeneous signal was found and either a low or low-high mixed signal on T2-weighted images in particular. These features are useful for the differential diagnosis of SFTs and other tumors.

Meningeal solitary fibrous tumor/hemangiopericytoma: Emphasizing on STAT 6 immunohistochemistry with a review of literature.

The 2016 central nervous system (CNS) World Health Organisation (WHO) Update has merged the entities of meningeal solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) into a single entity based on the presence of the nerve growth factor 1A (NGFI-A) binding protein 2 (NAB2)- signal transducer and activator of transcription 6 (STAT6) gene fusion in these tumors. Immunohistochemical (IHC) staining with STAT6 results in a strong nuclear positivity confirming the diagnosis. Meningeal SFT/HPCs are currently histologically graded according to a three-tiered system. Grade I (SFT phenotype) is benign, whereas grades II and III (HPC phenotype) are malignant and require radiotherapy in addition to gross total resection. The objectives were to review the cases diagnosed as meningeal SFT or HPC between 2010 and 2017 and classify them into SFT (grade I) or HPC (grades II and III) phenotypes; to confirm the diagnosis by performing STAT6 immunohistochemistry; and to observe and record the histological features in detail and correlate the tumor grades with their behavior. The published literature on the subject was also reviewed. A total of 21 cases diagnosed between 2010 and 2017 as meningeal SFT or HPC were included in the study. All cases were reviewed by the authors and were categorized and graded according to histologic phenotype and mitotic count. STAT6 immunohistochemistry was performed in all the cases. The epidemiological data and histologic findings in each case were recorded in detail. The follow-up of patients was obtained. Fifteen patients were males and six were females. The mean age was 43.5 years. The mean tumor size was 6.8 cm. The tumor specimens in 20 out of 21 cases corresponded to the HPC phenotype, of which 6 were in grade II while 14 were in grade III. Thus, over 95% cases had malignant lesions. The tumor in all the 21 cases recruited for the study showed immunohistochemical positivity for SAT6, while CD34 was positive in all the 18 tumor in which it was performed. The follow-up was available in 14 of the patients. Recurrence occurred in six patients who had either a grade II or a grade III tumor and three patients died (including one patient with a grade III tumor. This patient died a month after initial resection although there was no evidence of recurrence). Radiotherapy was given to only 4 out of 14 patients in whom follow-up was available. These rare tumors need to be accurately diagnosed and optimally treated (gross total resection and radiotherapy) to improve the prognosis.