Meningeal Hemangiopericytoma Research Articles

Descriptive epidemiology of 399 histologically confirmed newly diagnosed meningeal solitary fibrous tumours and haemangiopericytomas in France: 2006-2015.

Meningeal solitary fibrous tumour (SFT) and haemangiopericytoma (HPC) are uncommon tumours that have been merged into a single entity in the last 2021 WHO Classification of Tumors of the Central Nervous System. To describe the epidemiology of SFT/HPC operated in France and, to assess their incidence. We processed the French Brain Tumour Database (FBTDB) to conduct a nationwide population-based study of all histopathologically confirmed SFT/HPC between 2006 and 2015. Our study included 399 SFT/HPC patients, operated in France between 2006 and 2015, in one of the 46 participating neurosurgical centres. The incidence reached 0.062, 95%CI[0.056-0.068] for 100,000 person-years. SFT accounted for 35.8% and, HPC for 64.2%. The ratio of SFT/HPC over meningioma operated during the same period was 0.013. SFT/HPC are about equally distributed in women and men (55.9% vs. 44.1%). For the whole population, mean age at surgery was 53.9 (SD ± 15.8) years. The incidence of SFT/HPC surgery increases with the age and, is maximal for the 50-55years category. Benign SFT/HPC accounted for 65.16%, SFT/HPC of uncertain behaviour for 11.53% and malignant ones for 23.31%. The number of resection progresses as the histopathological behaviour became more aggressive. 6.7% of the patients with a benign SFT/HPC had a second surgery vs.16.6% in case of uncertain behaviour and, 28.4% for malignant SFT/HPC patients. Meningeal SFT and HPC are rare CNS mesenchymal tumours which both share common epidemiological characteristics, asserting their merging under a common entity. SFT/HPC incidence is less that one case for 1 billion per year and, for around 100 meningiomas-like tumours removed, one SFT/HPC may be diagnosed. SFT/HPC are equally distributed in women and men and, are mainly diagnosed around 50-55years. The more aggressive the tumour, the higher the probability of recurrence.

Gross Tumor Resection Followed by Post-Operative Radiation Optimizes Local Control in Patients with Meningeal Hemangiopericytoma: An Update on a Single Institutional Experience

<h3>Purpose/Objective(s)</h3> Meningeal hemangiopericytomas (M-HPCs) are vascularized mesenchymal tumors with aggressive behavior, commonly arising intracranially. The ideal treatment regimen for M-HPC varies from institution to institution, given its rare incidence. We have previously reported that both gross tumor resection (GTR) and post-operative radiotherapy (PORT) independently correlate with improved local control (LC), and that GTR followed by PORT at a dose ≥ 60 Gy improves LC. Here, we provide an update to those initial findings with extended follow-up in an expanded cohort of patients. <h3>Materials/Methods</h3> A single-institution retrospective analysis was conducted by reviewing the medical records of patients presenting with localized M-HPC at to a tertiary referral cancer center, between 1979 and 2021. The Kaplan-Meier method was used estimate actuarial LC, metastasis-free survival (MFS), and overall survival (OS). <h3>Results</h3> We identified 82 patients diagnosed between 1979 and 2021 with localized M-HPC that were treated with surgery alone (n=36) or surgery + PORT (n=46). Most patients were male (n=48, 59%), with a median age of 41 years (interquartile range 34-52). Median follow-up was 114 months. Most patients had intracranial tumors arising in the supratentorial region (n=50, 61%). There were also 5 patients who presented with disease in the cervical spine (6%). GTR was accomplished in 39 patients (49%) versus subtotal resection (STR) in 29 (37%), and unknown status in 14 patients (14%). PORT was delivered to the majority of patients (n=46, 56%). For the entire cohort, 5- and 10-year OS were 91% and 66%, and 5- and 10-year LC were 65% and 34%. Additionally, 5- and 10-year MFS were 82% and 41%. Undergoing GTR was associated with improved LC (HR 0.40, p=0.014). Similarly, PORT resulted in improved LC relative to patients who underwent surgery alone (HR 0.27, p<0.0001). Patients who underwent a GTR followed by PORT had superior LC compared to patients who had GTR alone (HR 0.18, p=0.001). Among intracranial tumors, patients receiving adjuvant radiation equivalent-dose in 2 Gy fractions (EQD2) ≥ 60 Gy (n=15) had improved LC relative to EQD2 doses of < 60 Gy (n=16) (HR 0.20, p=0.011). Age, gender, and PORT did not correlate with differences in OS or MFS. <h3>Conclusion</h3> Our data in this expanded cohort with prolonged follow-up demonstrate that among patients with M-HPC, PORT and GTR each independently improve LC. However, the combination of both GTR followed by PORT is superior to GTR alone for LC and should remain standard of care. Additionally, for patients with intracranial disease, PORT EQD2 doses ≥ 60 Gy should be used to improve LC.

An Exceptional Case Report On Spinal Hemangiopericytoma in a Young Male Patient

A rare incidence of primary intraspinal meningeal hemangiopericytoma (HPC) is described in this study. A 27-year-old man with low back pain extending to bilateral lower limbs had an MRI that indicated Tuberculosis of the Vertebral Body at L5 level, which was histopathologically diagnosed as HPC. The abscess was removed, and the patient's spine was stabilised. Complete surgical excision and follow-up radiotherapy appear to be the treatment of choice, regardless of the subtype of spinal HPC.

Meningeal Hemangiopericytoma: A Rare Intracranial Tumor—About a Case

Introduction: Hemangiopericytoma is a very rare vascular tumor, difficult to diagnose, often confused with a meningioma. Imaging is not very specific and the diagnostic certainty remains histological. Observation: We report a case of meningeal hemangiopericytoma in a 48-year-old patient with a history of active smoking and whose sister died of glioblastoma. He was brought to the emergency room for a fall, confusion, and tonic-clonic seizures. The diagnosis was suspected on imaging (CT and MRI, in front of a syndrome of right temporal intraventricular mass measured at 37 mm in diameter, centered on the choroid plexus, with perilesional vasogenic edema and posterior white commissure. There was homogeneous enhancement of the lesion after gadolinium injection. The diagnosis was confirmed by immunohistochemical study, which showed diffuse expression of STAT6 and partial labeling for CD34, without significant expression of SSTR2. Expression of neurofilament protein was also found in the brain parenchyma. Conclusion: Hemangiopericytoma is a rare tumor, characterized by its malignant potential, its high rate of recurrence and distant metastasis. The management is based on a total microsurgical resection followed by radiotherapy.

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.

Aggressive Behavior Predictors in Solitary Fibrous Tumor: Demographic, Clinical, and Histopathologic Characteristics of 81 Cases.

Solitary fibrous tumor (SFT) is a rare mesenchymal tumor with an intermediate tendency to metastasize. Meningeal hemangiopericytoma (HPC), arising in the meningeal membranes, also is considered an SFT. Although SFT is assumed to show an unpredictable behavior, the authors defined some factors associated with its aggressive behavior. This retrospective study was based on the medical records of 81 SFT patients treated surgically, with the median follow-up period of 59 months. The patients were assigned to three histopathologic groups based on the 2016 WHO classification: group 1 (SFT, 29 patients), group 2 (cellular SFT/hemangiopericytoma [HPC], 27 patients), and group 3 (malignant SFT/anaplastic HPC, 25 patients). The SFT histopathologic classification was associated with distant metastasis (DM) (p = 0.007). The multivariate analysis showed that cellular SFT had an independent impact on DM (odds ratio [OR] = 25.42; p = 0.006). Tumor diameter larger than 7.25cm was correlated with DM (p = 0.010) and the patient's disease-specific death (DSD) (p = 0.007). A 1-cm increase in tumor diameter enhanced the likelihood of metastasis by 1.26 (OR = 1.26; 95% confidence interval [CI], 1.05-1.53). Tumors originating from the central nervous system (CNS) showed a greater tendency toward local recurrence (LR) (p = 0.039) and DM (p = 0.05). Radiotherapy had no association with LR, DM, or DSD. The 10-year disease-specific survival rate was 82.7%. Tumor size and histopathologic diagnosis are the predictors of SFT's aggressive behavior. Cellular SFTs behave as aggressively as the malignant form of the tumor. A SFT grading based on SFT cellularity would contribute to anticipation of its aggressive behavior.

Concurrent Hepatic and Renal Metastases of a Meningeal Hemangiopericytoma: A Case Report and Review of the Literature

Concurrent Hepatic and Renal Metastases of a Meningeal Hemangiopericytoma: A Case Report and Review of the Literature

Quoi de neuf dans la prise en charge des tumeurs fibreuses solitaires/hémangiopéricytomes des méninges ?

Meningeal fibrous solitary tumors/hemangiopericytoma are rare and aggressive mesenchymal neoplasms considered as sarcomas. They represent less than 1% of intracranial tumors and derive from the pericytes of Zimmerman which permit capillary contraction. They tend to occur more often in males in the fifth decade. They are often revealed by intracranial hypertension. Some scannographic and MRI characteristics permit to distinguish meningeal fibrous solitary tumor/hemangiopericytoma from other meningeal tumors. Meningeal hemangiopericytoma and fibrous solitary tumors were considered as different entities until 2016. Following the discovery of an identical genetic event, the locus 12q13 chromosome inversion leading to a NAB2-STAT6 fusion with nuclear immunoreactivity for STAT6 protein, the 2016 WHO classification defines these tumors as a single entity. Meningeal fibrous solitary tumors/hemangiopericytoma have a high recurrence rate. Long-term recurrences may occur. Local relapses are more frequent than extracranial metastasis. A multimodal management is recommended to treat a localized disease. It involves a complete resection followed by adjuvant radiotherapy. When local recurrences occur, surgery or stereotactic radiosurgery permit sometimes a local control. Metastatic disease has a poor prognostic and a weak chimiosensitivity. Targeted therapies, like pazopanib, are a hopeful option.

Atypical meningeal hemangiopericytoma presenting with punched-out calvarial erosion

Meningeal hemangiopericytoma (HPC) is an infrequent but distinct entity affecting the craniospinal axis. A previously healthy 48-year-old man sustained a gradually progressing motor weakness in the left lower extremity. CT showed a hyperdense mass in the right frontal lobe. On MRI, it was 29 × 30 × 36 mm in dimension, appeared isointense on T1 and hyperintense on T2, and was intensely enhanced with erosive changes in the inner table adjacent to the tumor. The patient underwent tumor resection. Reflection of the bone flap revealed a punched-out erosion in the inner table with a defect of the dura over the upper part of the tumor. Microscopic findings were consistent with grade III HPC with dural invasion. A punched-out calvarial erosion and dural defect caused by an extra-axial tumor may be a high-grade HPC that requires extensive surgical resection.

Radiation therapy in treatment of patients with meningeal hemangiopericytoma (solitary fibrous) tumor of dura mater

Tactics of treating patients with meningeal hemangiopericytoma, or a solitary fibrous tumor of the dura mater remains controversial due to their rarity and heterogeneity of global experience, however, analysis of clinical data indicates that the best results are achieved when performing a total removal of the primary tumor and then following a course of external-beam radiation therapy on surgical bed in adequate total doses.

Intracranial Meningeal Hemangiopericytomas: An Analysis of Factors Affecting Outcome in 39 Cases Managed with Multimodality Treatment.

To retrospectively evaluate the outcome of patients with intracranial meningeal hemangiopericytomas (MHPCs) and to analyze various factors for recurrence and survival in these patients. We retrospectively reviewed the clinical data of 39 patients undergoing microsurgical resection for MHPCs at our institute from 2009 to 2015. Gross total excision (GTE) was achieved in 27 (69.2%) patients, whereas 12 (30.8%) underwent subtotal excision (STE). A total of 25 patients received radiotherapy (RT) (Conventional RT-15; GKT-10), 21 patients had a low grade tumor, while 18 had an anaplastic variant. Twenty patients (51.3%) developed recurrences and the average recurrence-free survival (RFS) was 56 months (range: 12-180 months). Eight patients (20.5%) died during the study period. The average overall survival (OS) was 77.2 months (range: 36-192 months). Two patients (5.1%) developed systemic metastases during follow-up. Patient age was not found to affect RFS or OS. GTE was associated with prolonged RFS and OS but the impact was not statistically significant (P-values = 0.160 and 0.414, respectively). Low tumor grade was associated with statistically significant longer RFS as well as OS (P-values = 0.049 and 0.013, respectively). Addition of adjuvant RT was associated with statistically significant prolongation of RFS (P value = 0.016); however, it was not associated with statistically significant OS benefits (P-value = 0.758). Our study suggests that a greater extent of excision, lower tumor grade, and addition of adjuvant RT have a positive impact on both RFS and OS; however, low grade and adjuvant RT were the only factors associated with statistically significant prolongation of RFS and only tumor grade was associated with statistically significant OS benefits.

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.

Non-islet-cell tumour hypoglycaemia (NICTH): About a series of 6 cases

The purpose of this study was to analyse the characteristics of 6 patients managed in a university hospital between 1996 and 2016 for non-islet cell tumor hypoglycemia (NICTH), a form of hypoglycaemia due to the paraneoplastic secretion of IGF-2 or its related substances. ResultsThree of these 6 patients (50%), aged over 69 years, including 2 with acromegaloid phenotype, presented with a pleural solitary fibrous tumor (SFT), with median diameter 20 cm (interquartile range, 12.5–20.5) with a low median SUV (3.3 g/mL (QR, 2–7.5)) on 18F-FDG PET. The other 3 patients presented respectively neuroendocrine carcinoma (NEC) of the palate (70-year-old woman), retroperitoneal myxofibrosarcoma (66-year-old man) and meningeal hemangiopericytoma (36-year-old woman). All 3 were inoperable and did not respond to any therapy other than glucose solution. Corticosteroid therapy was effective in the 3 SFTs and the NEC. One of the SFTs recurred 10 years later with asymptomatic hypoglycemia, which resolved after reintervention. Median (IQR) blood glucose levels of the 6 patients was 0.4g/L (QR, 0.31–0.41), with hypoinsulinemia at 0.7mIU/L (QR 0.7–2.0), undetectable GH, low IGF-1, normal IGF-2 level in 5/6 cases, a high IGF-2:IGF-1 ratio at 26.9 (QR, 20.8–37.8), hypokalemia and hypomagnesemia. ConclusionNICTH is a rare syndrome, which should be considered in the presence of hypoinsulinemic hypoglycemia with low GH and IGF-1, and a IGF-2:IGF-1 ratio>10. Corticosteroid therapy was effective in elderly subjects, particularly with solitary fibrous tumor, which was generally operable. Hemangiopericytoma and myxofibrosarcoma had poor prognosis in younger patients.

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.

Meningeal haemangiopericytoma and solitary fibrous tumour: a retrospective bi centre study for outcome and prognostic factor assessment.

To describe the outcome of patients diagnosed with central nervous system haemangiopericytoma (HPC) or solitary fibrous tumour (SFT) and identify factors that may influence recurrence and survival. Between January 2000 and September 2016, a retrospective search identified 55 HPCs/SFTs. The patients underwent a total of 101 surgical resections and 56.9% received radiation therapy. Median follow-up was 7.8 years. 28 patients (50.9%) were re-operated for tumour recurrence. At the end of the study, 21 patients (42%) had no residual tumour on the last scan. Surgical recurrence-free survival at 5 years was 75.2%, 95% CI [63.3-89.3] and, the median surgical recurrence-free survival was 7.4 years. In the adjusted analysis, venous sinus invasion (present vs. absent) (HR 3.39, 95% CI [1.16, 9.93], p = 0.026), completeness of resection (HR 0.38, 95% CI [0.15-0.97], p = 0.042) and tumour subtype (SFT vs. HPC) (HR 3.02, 95% CI[1.02, 8.91], p = 0.045) were established as independent prognostic factors. At the end of the study, 25 patients were deceased (45.5%). and only 15 patients (27.3%) had no residual tumour on the last scan and were alive. Overall survival at 5 years was 80.2, 95% CI [69.3-92.8] and the median overall survival was 13.1 years. None of the investigated variables was associated with overall survival. Patients who received radiation therapy demonstrated neither a reduced risk of surgical recurrence (p = 0.370) nor a longer overall survival (p = 1.000). SFTs/HPCs are associated with a significant risk of recurrence that may reduce the survival of the patients. Total tumour resection upon initial surgery is associated with a lower risk of relapse but not with a prolonged survival. We did not observe a significant improvement in any of the clinical outcomes after radiation therapy.

Invasiveness is associated with metastasis and decreased survival in hemangiopericytoma of the central nervous system.

Meningeal hemangiopericytoma (m-HPC) is a rare tumor of the central nervous system (CNS), which is distinguished clinically from meningioma by its tendency to recur and metastasize. The histological classification and grading scheme for m-HPC is still evolving and few studies have identified tumor features that are associated with metastasis. All patients at our institution with m-HPC were assessed for patient, tumor, and treatment characteristics associated with survival, recurrence, and metastasis. New findings were validated using the SEER database. Twenty-seven patients were identified in our institutional records with m-HPC with a median follow-up time of 85 months. Invasiveness was the strongest predictor of decreased overall survival (OS) and decreased metastasis-free survival (MFS) (p = 0.004 and 0.001). On subgroup analysis, bone invasion trended towards decreased OS (p = 0.056). Bone invasion and soft tissue invasion were significantly associated with decreased MFS (p = 0.001 and 0.012). An additional 315 patients with m-HPC were identified in the SEER database that had information on tumor invasion and 263 with information on distant metastasis. Invasion was significantly associated with decreased survival (HR = 5.769, p = 0.007) and metastasis (OR 134, p = 0.000) in the SEER data. In this study, the authors identified a previously unreported tumor characteristic, invasiveness, as the strongest factor associated with decreased survival and metastasis. The association of invasion with decreased survival and metastasis was confirmed in a separate, larger, publicly available database. Invasion may be a useful parameter in the histological grading and clinical management of hemangiopericytoma of the CNS.

Meningeal hemangiopericytomas: Imaging features helpful in distinguishing these tumors from meningiomas (P3.153)

Meningeal hemangiopericytomas: Imaging features helpful in distinguishing these tumors from meningiomas (P3.153)

Meningioma mimicking Haemangiopericytoma: A Rare Case Report

A wide spectrum of dural lesions occurs which is mimicking meningioma. The meningeal haemangiopericytoma is a rare tumor of meninges that is difficult to distinguish from meningioma; however both are treated similarly with surgical resection with or without radiotherapy to reduce the risk of recurrence. Macroscopically many haemangiopericytoma resemble to meningioma but are distinct histologically. These tumors show more aggressive natural history. Vascular nature of tumor suggests a different therapeutic approach thus fore warning a surgeon to a potentially more challenging resection.Journal of National Institute of Neurosciences Bangladesh 2015;1(2): 69-71

RADIATION THERAPY OF MENINGEAL HEMANGIOPERICYTOMAS (LITERATURE REVIEW AND CLINICAL OBSERVATION)

Meningeal hemangiopericytomas are rare tumors of the meninges developing from pericytes. The main method of their treatment is surgery aimed at total removal of the tumor. Analysis of the literature studies shows high potential of post-operative distant radiation therapy to increase duration of relapse-free survival of these patients. The recommended total radiation dose varies from 50 to 60 Gy (and in some publications, it exceeds 60 Gy). Radiation is applied as classic fractionation and hypofractionation, and different types of radiosurgery and stereotaxic radiotherapy are suitable approaches to treatment of recurrent meningeal hemangiopericytomas in patients with a history of radiation therapy.

Recurrent Intracranial Meningeal Hemangiopericytoma with an Isolated Bone Metastasis: A Case Report and Literature Review

Recurrent Intracranial Meningeal Hemangiopericytoma with an Isolated Bone Metastasis: A Case Report and Literature Review