Imaging features of central nervous system haemangiopericytomas

Preoperative MRI-based radiomic nomogram for distinguishing solitary fibrous tumor from angiomatous meningioma: a multicenter study

Purpose

This study evaluates the efficacy of radiomics-based machine learning methodologies in differentiating solitary fibrous tumor (SFT) from angiomatous meningioma (AM).

Materials and methods

A retrospective analysis was conducted on 171 pathologically confirmed cases (94 SFT and 77 AM) spanning from January 2009 to September 2020 across four institutions. The study comprised a training set (n=137) and a validation set (n=34). All patients underwent contrast-enhanced T1-weighted (CE-T1WI) and T2-weighted(T2WI) MRI scans, from which 1166 radiomics features were extracted. Subsequently, seventeen features were selected through minimum redundancy maximum relevance (mRMR) and the least absolute shrinkage and selection operator (LASSO). Multivariate logistic regression analysis was employed to assess the independence of these features as predictors. A clinical model, established via both univariate and multivariate logistic regression based on MRI morphological features, was integrated with the optimal radiomics model to formulate a radiomics nomogram. The performance of the models was assessed utilizing the area under the receiver operating characteristic curve (AUC), accuracy (ACC), sensitivity (SEN), specificity (SPE), positive predictive value (PPV), and negative predictive value (NPV).

Results

The radiomics nomogram demonstrated exceptional discriminative performance in the validation set, achieving an AUC of 0.989. This outperformance was evident when compared to both the radiomics algorithm (AUC= 0.968) and the clinical model (AUC = 0.911) in the same validation sets. Notably, the radiomics nomogram exhibited impressive values for ACC, SEN, and SPE at 97.1%, 93.3%, and 100%, respectively, in the validation set.

Conclusions

The machine learning-based radiomic nomogram proves to be highly effective in distinguishing between SFT and AM.

Intracranial Solitary Fibrous Tumor/Hemangiopericytoma: A Series of 14 Cases and Review of the Literature

Solitary fibrous tumor (SFT) is a rare type of tumor characterized by spindle-shaped cells originating from mesenchymal tissue. This case series presents a collection of 14 intracranial solitary fibrous tumors treated between 2014 and 2022 in our institute in Bucharest, Romania. Through a systematic investigation, key aspects spanning the preoperative, intraoperative, and postoperative phases of patient care were highlighted. Our study examines various factors including tumor location (which was very heterogeneous), size (median of 49 mm, ranging between 22 mm and 70 mm), surgical techniques employed, and recurrence rates. The data was analyzed using Python version 3.10 (Python Software Foundation, Wilmington, Delaware, United States). Gender disparities in SFT were noted, particularly the male-to-female ratio which was 5:9. The use of the Medical Research Council (MRC) Scale for Muscle Strength aided in evaluating severity and postoperative outcomes. GTR was achieved in nine out of 14 cases (64.28%), prolonging the period of recurrence-free survival.

Imaging Characteristics and Surgical Outcomes in Patients With Intraspinal Solitary Fibrous Tumor/Hemangiopericytoma: A Retrospective Cohort Study

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Intraspinal solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) is often misdiagnosed preoperatively as schwannoma or meningioma because its imaging characteristics are not well understood. As postoperative prognosis differs among the 3 lesions, predicting the probability of SFT/HPC preoperatively is essential. Thus, this study investigates the imaging characteristics of SFT/HPC compared with those of schwannoma or meningioma and evaluates surgical outcomes.

METHODS

The preoperative imaging findings, tumor resection extent, recurrence and regrowth rates, and neurological improvement were compared between 10 patients with SFT/HPC and 42 patients with schwannoma or 40 patients with meningioma.

RESULTS

Most patients with SFT/HPC showed isointensity on both T1- and T2-weighted images compared with patients with schwannoma (P = 0.011 and 0.029, respectively) and no significant difference compared with patients with meningioma (P = 0.575 and 0.845, respectively). Almost all patients with SFT/HPC showed highly uniformizing enhancement patterns, similar to those with meningioma (P = 0.496). Compared with meningioma, SFT/HPC lacked the dural tail sign and intratumoral calcification and exhibited irregular shape. Of the 5 patients who underwent partial resection, 60% exhibited tumor recurrence and regrowth following surgery.

CONCLUSIONS

Complete en bloc surgical resection should be attempted in patients with intraspinal SFT/HPC to prevent postoperative recurrence or regrowth. As this tumor is often preoperatively misdiagnosed, we recommend that the imaging findings exhibited in this study should be used to positively suspect SFT/HPC. This will enhance patient outcomes by enabling more appropriate preoperative surgical planning.

Rare magnetic resonance imaging findings of intracranial solitary fibrous tumor: A case report

RATIONALE

Solitary fibrous tumor (SFT) is a rare mesenchymal spindle cell tumor. SFT in the central nervous system (CNS) is rare. This case reports rare magnetic resonance imaging (MRI) findings of intracranial SFT (ISFT).

PATIENT CONCERNS

We report a 47-year-old female patient who was found to have weakness in her right limb with walking instability 2 months before the visit.

DIAGNOSES

Based on imaging, the provisional diagnosis was meningioma. Postsurgical histopathological diagnosis confirmed World Health Organization (WHO) grade I SFT/hemangiopericytoma (HPC).

INTERVENTIONS

The lesion was totally excised. The patient improved remarkably after the operation, without any signs of associated limb movement disorder.

OUTCOMES

No local recurrence or metastases were observed in the follow-up 3 months after the surgery.

LESSONS

Intracranial SFT is a rare mesenchymal tumor. Due to different tumor components, imaging manifestations are diverse and lack of characteristics, so preoperative diagnosis is challenging. Our case provides a rare ISFT with significantly decreased signal intensity in T2 weighted images (T2WI), which is an important supplement to the rare imaging findings of intracranial SFT.

Case report: Primary intracranial EWs/PNET in adults: Clinical experience and literature review

Introduction

Adult primary intracranial Ewing sarcomas (EWs)/primitive neuroectodermal tumors (PNETs) are extremely rare, with only 30 patients published before us. The imaging features and treatment strategies of primary intracranial EWs/PNETs are unclear due to its rarity. The aim of this study was to investigate the clinical features, imaging findings, treatment, survival analysis, and prognosis of adult EWs/PNETs, and a systematic review was conducted based on the patient we treated and published literature.

Case description

A 19-year-old male patient suffered from head pain due to an accidental fall on a motorcycle that occurred more than 10 days before going to the hospital, and underwent computed tomography (CT) examination; it was found that the left temporo-occipital fossa was occupied. Magnetic resonance imaging (MRI) was recommended to understand the nature of the lesion, and the result showed that it has a high probability of being a meningioma. He underwent surgical removal of the mass under general anesthesia, and surprisingly, postoperative pathology revealed EWs/PNET. The disease has a high degree of malignancy, and the patient developed multiple metastases throughout the body 5 years after surgery.

Conclusion

Primary intracranial EWs/PNETs in adult patients are rare, of which imaging findings should be considered as one of the differential diagnoses of meningioma, hemangiopericytoma, and malignant triton tumor. Larger solid-cystic masses with septum-like enhancement may be relatively specific imaging findings of intracranial EWs/PNETs. The prognosis of primary adult intracranial EWs/PNETs is poor. Radical tumor resection combined with radiotherapy and chemotherapy is currently the main and possibly the most effective treatment method.

Solitary Fibrous Tumor of the Spine: Imaging Grading Diagnosis and Prognosis

OBJECTIVE

This study aimed to investigate the imaging features and prognosis of spinal solitary fibrous tumors (SFTs) of different pathological grades.

METHODS

The clinical features, computed tomography and magnetic resonance (MR) images, and follow-up data of 23 patients with SFTs were reviewed. The patients were divided into 3 groups according to their pathological manifestations: grade 1 (n = 3), grade 2 (n = 14), and grade 3 (n = 6). The following imaging features were recorded: location, computed tomography density/MR intensity, enhancement pattern, dural tail sign, adjacent bone remodeling, lobulation, and tumor size. The immunohistochemical (Ki-67/MIB-1) levels were also investigated. All parameters were statistically analyzed between grade 2 and 3 tumors.

RESULTS

The Ki-67/MIB-1 index was markedly higher in grade 3 tumors than in grade 2 tumors (P < 0.001). All grade 1 lesions appeared hypointense on T2-weighted image, whereas grade 2 and 3 lesions appeared isointense or mildly hyperintense. There were significant differences in enhancement type and osteolytic bony destruction between grade 2 and 3 tumors (P < 0.05). However, no marked differences were found in the distribution of age, sex, location, MR signal, degree of enhancement, compressive bony absorption, dural tail sign, or maximum vertical/traverse diameter ratio. Malignant progression occurred less frequently in patients with grade 2 tumors than in those with grade 3 tumors, but the difference was not statistically significant.

CONCLUSIONS

Different grades of spinal SFTs have different degrees of proliferation and imaging features, especially grade 3 tumors, which show a heterogeneous enhancement pattern, osteolytic bony destruction, and a higher possibility of recurrence and metastasis.

Solitary fibrous tumor of the pineal region in the elderly: A case report

INTRODUCTION

Solitary fibrous tumor (SFT) is a mesenchymal tumor with spindle cells that is often detected in the subcutaneous area and rarely in the central nervous system. Intracranial SFTs rarely occur in individuals older than 80 years, and there are only a few cases reports involving the pineal region.

PRESENTATION OF CASE

The present case was an 80-year-old man with lightheadedness, headache, and vomiting. Magnetic resonance imaging showed a tumor in the pineal region extending along the falx and tentorium cerebelli with homogenous enhancement. Subtotal resection was performed via the occipital transtentorial approach. A histopathological examination showed the proliferation of oval- to spindle-shaped tumor cells with bland nuclei arranged in a haphazard pattern and accompanied by staghorn-like branching vessels. Immunohistochemically, tumor cells were positive for CD34 (focal), CD99, and STAT6, but negative for epithelial membrane antigen (EMA) and S-100. Based on these findings, the tumor was diagnosed as SFT (WHO grade I).

DISCUSSION

Although difficulties are associated with differentiating SFT from meningioma on imaging, recurrence and metastasis are more common with SFT than with meningioma; therefore, histological and immunohistochemical analyses are important. A correlation has been reported between postoperative adjuvant radiotherapy and longer progression-free survival; however, this needs to be confirmed in further studies.

CONCLUSION

SFT involving the pineal region is rare in the elderly, but needs to be considered as a preoperative diagnosis. Since high rates of postoperative recurrence and metastasis have been reported, long-term follow-ups are required after surgery.

Postoperative progression of intracranial grade II-III solitary fibrous tumor/hemangiopericytoma: predictive value of preoperative magnetic resonance imaging semantic features

BACKGROUND

Preoperative prediction of postoperative tumor progression of intracranial grade II-III hemangiopericytoma is the basis for clinical treatment decisions.

PURPOSE

To use preoperative magnetic resonance imaging (MRI) semantic features for predicting postoperative tumor progression in patients with intracranial grade II-III solitary fibrous tumor/hemangiopericytoma (SFT/HPC).

MATERIAL AND METHODS

We retrospectively analyzed the preoperative MRI data of 42 patients with intracranial grade II-III SFT/HPC, as confirmed by surgical resection and pathology in our hospital from October 2010 to October 2017, who were followed up for evaluation of recurrence, metastasis, or death. We applied strict inclusion and exclusion criteria and finally included 37 patients. The follow-up time was in the range of 8-120 months (mean = 57.1 months).

RESULTS

Single-factor survival analysis revealed that tumor grade (log-rank, P = 0.024), broad-based tumor attachment to the dura mater (log-rank, P = 0.009), a blurred tumor-brain interface (log-rank, P = 0.008), skull invasion (log-rank, P = 0.002), and the absence of postoperative radiotherapy (log-rank, P = 0.006) predicted postoperative intracranial SFT/HPC progression. Multivariate survival analysis revealed that tumor grade (P = 0.009; hazard ratio [HR] = 11.42; 95% confidence interval [CI] = 1.832-71.150), skull invasion (P = 0.014; HR = 5.72; 95% CI = 1.421-22.984), and the absence of postoperative radiotherapy (P = 0.001; HR = 0.05; 95% CI = 0.008-0.315) were independent predictors of postoperative intracranial SFT/HPC progression.

CONCLUSION

Broad-based tumor attachment to the dura mater, skull invasion, and blurring of the tumor-brain interface can predict postoperative intracranial SFT/HPC progression.

Primary endodermal hemangiopericytoma/solitary fibrous tumor of the cervical spine: a case report and literature review

Background

Hemangiopericytoma (HPC), also known as solitary fibrous tumor (SFT), is a type of soft tissue sarcoma with a special aggressive behavior. The HPC/SFT is locally aggressive with possibility of late recurrence locally or distant extraneural metastasis. The most common location of this HPC/SFT is the lower extremities. The HPC/SFT in the central nervous system (CNS) is very rare, and compared with the brain, it is rarer in the spinal region. However, clinicians also lack an overall understanding of the diagnosis of HPC/SFT in the spinal cord.

Case presentation

In this study, we report a rare case of primary cervical spine HPC/SFT in a 53-year-old woman. Two to three weeks before admission, she experienced pain and numbness in her left upper extremity. After computerized tomography (CT) and magnetic resonance imaging (MRI), a gross total resection was performed. Obvious neurological improvement was observed postoperatively. The pain and numbness in the patient's left upper limb were relieved subsequently. We then reviewed the literature on HPC/SFT, such as its clinical presentation, imaging characteristics, treatment, and follow-up.

Conclusions

Diagnosis of HPC/SFT relies on magnetic resonance spectroscopy, enhanced CT, and MRI. Postoperative radiotherapy is strongly recommended to reduce the HPC/SFT recurrence. Immunohistochemical analysis can also help in the differential diagnosis. However; early and long-term follow-up is necessary for patients.

Intracranial Solitary Fibrous Tumor of the Skull Base: 2 Cases and Systematic Review of the Literature

BACKGROUND

Intracranial solitary fibrous tumors (ISFTs) are rare neoplasms of mesenchymal origin that originate from the meninges. ISFTs of the skull base can be challenging to treat, as resection can be complicated by skull base anatomy. We present 2 cases of ISFT, the first manifesting with compressive cranial neuropathy from Meckel cave involvement and the second a posterior fossa lesion causing symptomatic hydrocephalus.

METHODS

A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The PubMed database was queried with title/abstract keywords "intracranial," "solitary fibrous tumor," "hemangiopericytoma," "SFT," and "HPC." Search results were reviewed to exclude cases not involving the skull base. References from all selected articles were reviewed for potential additional cases. Patient demographic and clinical data from 58 identified skull base cases were collected for qualitative synthesis.

RESULTS

Visual disturbances were the most common presenting symptom (30 cases, 52%) followed by headache (22 cases, 38%). The most common site of involvement was the sellar/parasellar region (18 cases, 31%) followed by middle fossa/temporal bone (14 cases, 24%). Resection was performed in 55 cases; gross total resection was reported in 26 cases (45%) and subtotal resection was reported in 21 cases (36%). Tumor recurrence was documented in 15 cases (26%) with median and mean follow-up periods of 16 and 29.9 months, respectively.

CONCLUSIONS

We discuss presentation, imaging, histopathology, and management considerations for ISFTs while highlighting the potentially complex nature of skull base lesions and need for multidisciplinary approach to treatment.

Angioarchitecture and Pre-Surgical Embolization of Central Nervous System Solitary Fibrous Tumor/Hemangiopericytoma

Objective

Hemangiopericytomas (HPCs) and solitary fibrous tumors (SFTs) have been categorized as the same disease entity, SFT/HPC, since 2016. SFT/HPC is one of the most highly vascularized brain tumors, distinct from meningioma. The angioarchitecture also differs between these tumors. Understanding these differences can help interventionalists perform presurgical embolization more safely and effectively.

Methods

Vascular structures were analyzed in eight patients with central nervous system (CNS) SFT/HPCs, all of whom received presurgical embolization. The type of embolic materials used and the complication rates were compared between the CNS SFT/HPC cases and 39 meningioma cases treated within the same period. Characteristic angiographic features of SFT/HPC were identified, and we present their interpretation and utilization to inform embolization strategies.

Results

Four angiographic features of SFT/HPCs were identified. 1) Persistence of tumor stain and 2) feeders from branches of the internal carotid artery or vertebral artery were observed in all cases, while 3) connecting feeders (highly dilated vessels that originate from branches of other feeder vessels and run along the surface of one tumor compartment to feed another compartment) were observed in five out of eight cases. 4) Finally, an intratumoral arteriovenous shunt was identified in one case. The frequency of liquid embolic material use was significantly higher in SFT/HPC cases than in meningioma cases. No complications were observed in SFT/HPC cases, and all tumors were effectively removed.

Conclusion

The most appropriate presurgical embolization strategies differ between SFT/HPCs and meningiomas depending on the tumor angioarchitecture. A thorough understanding of the vascular anatomy is necessary for safe and effective embolization of SFT/HPCs.

Intracranial anaplastic solitary fibrous tumor/hemangiopericytoma: immunohistochemical markers for definitive diagnosis

Intracranial anaplastic hemangiopericytoma (AHPC) is a rare and malignant subset of solitary fibrous tumor/hemangiopericytoma (SFT/HPC) as per the WHO 2016 Classification of Tumors of the Central Nervous System. AHPC portends a poor prognosis and is associated with higher rates of recurrence/metastasis in comparison with SFT/HPC. Accordingly, it is critical to continue to define the clinical course of patients with AHPC and in so doing further refine clinicopathologic/immunohistochemical (IHC) criteria needed for definitive diagnosis. Herein, we describe clinical/histological characteristics of six patients with AHPC. In addition, we reviewed and analyzed the expression of various IHC markers reported within the literature (i.e., a total of 354 intracranial SFT/HPCs and 460 meningiomas). Histologically, tumors from our six patients were characterized by a staghorn-like vascular pattern, mitotic cells, and strong nuclear atypia. Immunohistochemically, all tumors displayed positive nuclear staining for STAT6; other markers, including CD34 and Bcl-2, were expressed only in three patients. Analysis of IHC expression patterns for SFT/HPC and meningioma within the literature revealed that nuclear expression of STAT6 had the highest specificity (100%) for SFT/HPC, followed by ALDH1 (97.2%) and CD34 (93.6%). Of note, SSTR2A (95.2%) and EMA (85%) displayed a high specificity for meningioma. Anaplastic SFT/HPC is a tumor with poor prognosis that is associated with higher rates of recurrence and metastasis in comparison with SFT/HPC. Given that anaplastic SFT/HPC requires more aggressive treatment than meningioma despite of a similar presentation on imaging, it is crucial to be able to distinguish between these tumors.

Accurate Preoperative Distinction of Intracranial Hemangiopericytoma From Meningioma Using a Multihabitat and Multisequence-Based Radiomics Diagnostic Technique

Background: Intracranial hemangiopericytoma (IHPC) and meningioma are both meningeal neoplasms, but they have extremely different malignancy and outcomes. Because of their similar radiological characteristics, they are difficult to distinguish prior to surgery, leading to a high rate of misdiagnosis.

Methods: We enrolled 292 patients (IHPC, 155; meningiomas, 137) with complete clinic-radiological and histopathological data, from a 10-year database established at Tiantan hospital. Radiomics analysis of tumor and peritumoral edema was performed on multisequence magnetic resonance images, and a fusion radiomics signature was generated using a machine-learning strategy. By combining clinic-radiological data with the fusion radiomics signature, we developed an integrated diagnostic approach that we named the IHPC and Meningioma Diagnostic Tool (HMDT).

Results: The HMDT displayed remarkable diagnostic ability, with areas under the curve (AUCs) of 0.985 and 0.917 in the training and validation cohorts, respectively. The calibration curve showed excellent agreement between the diagnosis predicted by HMDT and the histological outcome, with p-values of 0.801 and 0.622 for the training and the validation cohorts, respectively. Cross-validation showed no statistical difference across three divisions of the cohort, with average AUCs of 0.980 and 0.941 for the training and validation cohorts, respectively. Stratification analysis showed consistent performance of the HMDT in distinguishing IHPC from highly misdiagnosed subgroups of grade I meningioma and angiomatous meningioma (AM) with AUCs of 0.913 and 0.914 in the validation cohorts for the two subgroups.

Conclusions: By integrating clinic-radiological information with radiomics signature, the proposed HMDT could assist in preoperative diagnosis to distinguish IHPC from meningioma, providing the basis for strategic decisions regarding surgery.

Hemangiopericytomas: Spatial Intracranial Location in a Voxel-Based Mapping Study

BACKGROUND AND PURPOSE

To investigate the preferred location of intracranial hemangiopericytomas (IHPCs) with voxel-based mapping and 3-dimensional reconstruction from MRI data.

METHODS

Gadolinium-enhanced tumors of 258 primary and single IHPCs were segmented semi-automatically, followed by manual checking and editing of boundaries. The lesions were registered to Montreal Neurological Institute standard anatomical space, and heat-map and 3-dimensional rendered frequency images were generated. All tumors were then superimposed on the Anatomical Automatic Labeling (AAL) template to further investigate the difference in the tumor location based on the voxel-wise frequency of occurrence with respect to laterality, sex, age, and pathologic grade.

RESULTS

The 3-dimensional rendered images show that the tumors commonly located in the posterior cranial cavity, surrounding the tentorium. The posterior third of the superior sagittal sinus and the confluence of sinuses were commonly affected. According to the analysis of tumor occurrence frequency in the AAL template, IHPCs were mainly observed in the limbic lobe, occipital lobe, and cerebellum. Tumors in younger patients preferentially located in the right occipital region (P = .027), whereas those with higher pathological grade more often located in the left parietal lobe (P = .034).

CONCLUSIONS

This is the first voxel-based study to explore the predilection site of IHPCs. Our study suggests that these tumors commonly affect the posterior cranial cavity, adjoining the tentorium and venous sinus. Further research is needed to investigate the possible factors underlying these topographic preferences.

Nervous System Hemangiopericytoma

The management of patients harboring central nervous system (CNS) hemangiopericytomas (HPCs) is a partially answered challenge. These are rare locally aggressive lesions, with potential for local recurrence, distal neural metastasis (DNM), and extraneural metastasis (ENM). Resection, when feasible, remains the initial treatment option, providing histological diagnosis and immediate relief of tumor-related mass effect. Patients receiving surgery alone or surgery and external beam radiotherapy (EBRT) show improved overall survival (OS) and progression-free survival as compared to those undergoing a biopsy alone (p = 0.01 and p = 0.02, respectively). Yet, in many instances, patient and tumor-related parameters preclude complete resection. EBRT or stereotactic radiosurgery (SRS) shares a significant role in achieving local tumor control, not shown to impact OS in HPC patients. The benefits of SRS/EBRT are clearly limited to improved local tumor volume control and neurologic function, not affecting DNM or ENM development. SRS provides acceptable rates of local tumor volume control coupled with treatment safety and a patient-friendly apparatus and procedure. Single-session SRS is most effective for lesions measuring <2 cm in their largest diameter (10 cm3 volume), with prescription doses of at >15 Gy. Systemic HPC disease is managed with various chemotherapeutic, immunotherapeutic, and anti-angiographic agents, with limited success. We present a short discussion on CNS HPCs, focusing our discussion on available evidence regarding the role of microsurgical resection, EBRT, SRS, chemotherapy, and immunotherapy for upfront, part of adoptive hybrid surgery approach or for recurrent HPCs.

Dural masses: meningiomas and their mimics

Meningiomas are the most common dural tumour. They are regularly being seen as an incidental finding on brain imaging and treated conservatively. However, there are many other dural masses which mimic their appearances, including primary neoplastic processes, metastases, granulomatous diseases and infection. While some of these are rare, others such as metastases and tuberculosis arise relatively frequently in practice. Although not pathognomonic, key features which increase the probability of a lesion being a meningioma include intralesional calcifications, skull hyperostosis, local dural enhancement and increased perfusion. It is important to have an awareness of these entities as well as their main imaging findings, as they have a wide range of prognoses and differing management strategies. This review outlines several of the most important mimics along with their imaging findings on both standard and advanced techniques with key features which may be used to help differentiate them from meningiomas.

Apparent diffusion coefficient values in differential diagnosis and prognostic prediction of solitary of fibrous tumor/hemangiopericytoma (WHOII) and atypical meningioma

BACKGROUND

It is difficult to distinguish solitary of fibrous tumor/hemangiopericytoma (SFT/HPC) from atypical meningioma (AM) by conventional imaging.As far as we know,diffusion weighting imaging may identify them effectively.

OBJECTIVE

The purpose of this study was to determine the role of apparent diffusion coefficient (ADC) values to distinguish and predict prognosis of solitary of fibrous tumor/hemangiopericytoma (SFT/HPC) (WHOII) and atypical meningioma (AM).

METHODS

Preoperative diffusion-weighted imaging (DWI) of 30 cases with histopathologic and immunhistochemical testified SFT/HPC WHOII (n= 11) and AM (n= 19) were performed retrospectively. The ADC values of lesion, peritumoral edema, normal white matter and lesion NADC ratio (lesion ADC values/ADC values of normal white matter (NWN ADC)) were compared. The immunhistochemical markers (Ki-67, CD34, Vim, EMA, GFAP, S-100, PR, CD56) were compared. The correlation between the ADC values and Ki-67 index was evaluated.

RESULTS

The mean lesion ADC values of SFT/HPC (1.15 ± 0.04 × 10-3 mm2/s) was significantly higher than that of AM (0.80 ± 0.04 × 10-3 mm2/s) (t= 23.824, p< 0.05). The mean NADC ratio was lower for AM (1.03 ± 0.06) compared with SFT/HPC (1.51 ± 0.05) (t= 23.105, p< 0.05). The mean edema ADC for SFT/HPC (1.47 ± 0.06 × 10-3 mm2/s) was lower compared with AM (1.68 ± 0.05 × 10-3 mm2/s) (t=-9.926, p< 0.05 ). There was no statistical difference between the two groups of NWM ADC (t=-1.475, p> 0.05) . The mean Ki-67 of SFT/HPC (7.18 ± 2.60%) was lower than the mean Ki-67 of AM (13.58 ± 4.50%) (t=-4.934, p< 0.05). The CD34 showed statistically differences between two groups (X2= 13.659, p< 0.05). The EMA also showed statistically differences between two groups (X2= 4.474, p< 0.05). Vim,GFAP, S-100, PR, CD56 showed no statistical difference in the two group (p> 0.05). The pearson analysis indicated that there was a negative correlation between lesion ADC and Ki-67 in SFT/HPC group (r=-0.770, p< 0.05) and AM group (r=-0.727, p< 0.05). There was also a negative correlation between lesion NADC ratio and Ki-67 in SFT/HPC group (r=-0.673, p< 0.05) and AM group (r=-0.707, p< 0.05). There was a positive correlation between edema ADC and Ki-67 in SFT/HPC group (r= 0.819, p< 0.05) and AM group (r= 0.942, p< 0.05). Furthermore,there was no correlation between NWM A DC and Ki-67 in SFT/HPC group (r=-0.403, p> 0.05) and AM group (r= 0.202, p> 0.05).

CONCLUSIONS

The lesion ADC, lesion NADC ratio and edema ADC can distinguish the SFT/HPC WHO II from AM and be helpful to predict prognosis of the two tumors before operation. Further more, histopathologic and immunhistochemical can make a definite diagnosis of the two tumors.

Preoperative Assessment of Pathologic Subtypes of Meningioma and Solitary Fibrous Tumor/Hemangiopericytoma Using Dynamic Computed Tomography: A Clinical Research Study

BACKGROUND

Solitary fibrous tumors (SFTs)/hemangiopericytomas (HPCs) are highly vascularized tumors well known for malignant, invasive, and highly vascular features. To date, several studies have reported the preoperative imaging findings of SFTs/HPCs. In this study, computed tomography (CT) tumor values acquired from dynamic CT scan were selected to determine the tumor pathology of highly vascular tumors, such as SFTs/HPCs.

METHODS

We conducted a retrospective study on patients with pathologically diagnosed meningiomas and SFTs/HPCs who had undergone a dynamic contrast CT scan. We assessed and compared the CT values of these tumors according to the pathology.

RESULTS

From a total of 34 patients, 30 patients with meningiomas and 4 patients with HPCs were included. The mean CT values of SFTs/HPCs and angiomatous meningioma were statistically significantly higher than those of the other meningioma subtypes (P = 0.003). We also performed receiver operating characteristic curve analyses to detect an appropriate cutoff point for the CT value to differentiate tumor pathology, and the calculated threshold was 161 Hounsfield units (HU) (sensitivity, 100%; specificity, 75%; area under the curve, 0.87; 95%, CI 0.75-0.99).

CONCLUSIONS

This study showed that obtaining a CT value is useful in determining highly vascular tumor pathology preoperatively. When considering neurosurgical extra-axial tumor removal, and when the CT value of tumors is >161 HU, then highly vascular tumors such as SFTs/HPCs or angiomatous meningiomas are likely, and this should be considered prior to surgical intervention and for risk assessment.

Uncommon Cranial Meningioma: Key Imaging Features on Conventional and Advanced Imaging

Given the high incidence of intracranial meningiomas encountered in clinical practice, it is not uncommon to find rare subtypes of meningioma, with unusual imaging findings. These commonly represent a diagnostic challenge. In this article, we review the imaging appearance of typical meningioma on conventional and advanced imaging as well as the key imaging features of multiple uncommon subtypes: cystic, microcystic, lipomatous, chordoid, angiomatous, intraosseous, extracranial, atypical/malignant, and tumor-to-tumor metastasis (also known as collision tumors). Some of these uncommon subtypes, however, demonstrate imaging features that may allow for a more specific diagnosis, or features, which can influence patient's management.

Advanced Imaging of Intracranial Meningiomas

Although typically not necessary for the diagnosis of intracranial meningiomas, advanced imaging techniques, including perfusion and diffusion imaging, spectroscopy, and nuclear medicine imaging, can help confirm the diagnosis of intracranial meningiomas, especially for meningiomas that do not exhibit the typical anatomic imaging findings. Advanced imaging techniques also have the potential to be able to differentiate between the subtypes of meningiomas, predict clinical aggressiveness of the tumor, and better characterize response to treatment. Although no advanced imaging technique has been able to definitively subclassify meningiomas, current results are encouraging and may be helpful in surgical planning.

Angiographic Evidence of a Purely Pial Bihemispheric Intracranial Hemangiopericytoma

Background. Classification of hemangiopericytoma (HPC) has evolved to a mesenchymal, nonmeningothelial grade two or three neoplasm according to the World Health Organization; however its blood supply has always been defined by dual origin, pial and dural contribution. Case Description. We present the case of a patient with an intracranial HPC with only pial vascular supply. Angiography confirmed the lack of dural supply to this bihemispheric intracranial mass. Subsequent histologic examination confirmed the diagnosis of hemangiopericytoma. Angiographic evidence here is atypical of the natural history of hemangiopericytomas with dual vascular supply and was critical in the decision-making towards surgical resection without tumor embolization. Conclusion. Data presented suggests the lack of dural vascular supply alone does not rule out the diagnosis of hemangiopericytoma.

Extra-axial brain tumors

Extra-axial brain tumors are the most common adult intracranial neoplasms and encompass a broad spectrum of pathologic subtypes. Meningiomas are the most common extra-axial brain tumor (approximately one-third of all intracranial neoplasms) and typically present as slowly growing dural-based masses. Benign meningiomas are very common, and may occasionally be difficult to differentiate from more aggressive subtypes (i.e., atypical or malignant varieties) or other dural-based masses with more aggressive biologic behavior (e.g., hemangiopericytoma or dural-based metastases). Many neoplasms that typically affect the brain parenchyma (intra-axial), such as gliomas, may also present with primary or secondary extra-axial involvement. This chapter provides a general and concise overview of the common types of extra-axial tumors and their typical imaging features.

From the radiologic pathology archives: mass lesions of the dura: beyond meningioma-radiologic-pathologic correlation

Meningioma is the most common mass involving the dura, making it number one in the differential diagnosis for any dural-based mass; however, a variety of other neoplastic and nonneoplastic lesions also involve the dura. Knowledge of the dural anatomy can provide clues to the various processes that may involve this location. The neoplastic processes include both benign and malignant lesions such as hemangiopericytoma, lymphoma, solitary fibrous tumor, melanocytic lesions, Epstein-Barr virus-associated smooth muscle tumors, Rosai-Dorfman disease, and metastatic lesions. The nonneoplastic processes include infectious and inflammatory entities such as tuberculosis and sarcoid, which may mimic mass lesions. In some cases, neoplasms such as gliosarcoma may arise peripherally from the brain parenchyma, appearing dural-based and even inciting a dural tail. Many of these share similar computed tomographic, magnetic resonance imaging, and angiographic characteristics with meningiomas, such as a dural tail, increased vascularity, avid enhancement, and similar signal characteristics; however, knowledge of the patient's age, gender, and underlying conditions and certain imaging characteristics may provide valuable clues to recognizing these lesions. For example, in the population with human immunodeficiency virus infection, Epstein-Barr virus-associated smooth muscle tumors should be included in the differential diagnosis for dural-based lesions. The surgical course and prognosis for these lesions vary, and knowledge of the variety of lesions that involve the dura, their imaging appearances, and their clinical features assists in narrowing the radiologic differential diagnosis and optimizing patient treatment.

Comparison of ADC values of intracranial hemangiopericytomas and angiomatous and anaplastic meningiomas

PURPOSE

This study aimed to determine whether the use of apparent diffusion coefficient (ADC) values can improve the diagnostic efficacy of magnetic resonance imaging (MRI) to differentiate hemangiopericytoma (HPC) from angiomatous and anaplastic meningioma.

MATERIALS AND METHODS

Preoperative diffusion-weighted imaging (DWI) studies of 38 patients with pathologically proven intracranial HPC (n = 12) and angiomatous (n = 13) or anaplastic meningioma (n = 13) were retrospectively reviewed. ADC values were measured in the tumor parenchyma and peritumoral edema, and used to obtain normalized ADC (NADC) ratios (ADC of tumor/ADC of normal white matter).

RESULTS

Mean ADC values were significantly different between HPC and anaplastic meningioma (1.17 ± 0.30 × 10(-3) mm(2)/s and 0.75 ± 0.11 × 10(-3) mm(2)/s, respectively). Mean NADC ratios were also significantly lower in the malignant cases (0.95 ± 0.13) compared with the benign HPCs (1.53 ± 0.39; P < 0.05). Mean ADC values and NADC ratios did not differ significantly between angiomatous meningioma and HPC (P > 0.05), whereas mean ADC values and NADC ratios were lower for anaplastic meningioma than for either angiomatous meningioma or HPC (P < 0.05). Mean ADC value in peritumoral edema in HPC (1.48 ± 0.11 × 10(-3) mm(2)/s) was lower than in either angiomatous (1.73 ± 0.28 × 10(-3) mm(2)/s) or anaplastic (1.72 ± 0.25 × 10(-3) mm(2)/s) meningioma (P < 0.05), and there was no significant difference between ADC values in anaplastic versus angiomatous meningioma (P > 0.05).

CONCLUSION

ADC values in tumor parenchyma and peritumoral edema can provide helpful information that is otherwise not available from conventional MRI to differentiate HPC from angiomatous and anaplastic meningioma.

What lies beneath

Haemangiopericytomas are a group of aggressive soft tissue sarcomas that originate from the pericytes in the walls of capillaries. Local invasion of the surrounding structures is not uncommon. Symptoms depend on the location, size and grade of tumour. Coexistence with a benign tumour in the same location is very rare. We report an interesting case of occipital scalp lipoma with an underlying torcular haemangiopericytoma and skull defect.

Haemangiopericytoma presenting with acute intracerebral haemorrhage--a case report and literature review

BACKGROUND

Intracranial haemangiopericytoma (HPC), a rare malignant tumour, should be distinguished from meningioma and solitary fibrous tumour, which have been considered as separate entities since 1993, according to histopathology and clinical characteristics.

METHODS

A PUBMED search for "Intracranial Haemangiopericytoma" yielded 176 articles, where 26 were of particular interest for this review article.

CASE REPORT

Our patient, a 27-year-old man with HPC of grade III according to WHO, presents with an acute intracerebral haematoma, which is extremely rare.

RESULTS

Surgery (total resection) is the primary treatment. Long-term close clinical and radiological follow-up is crucial due to the high rate of recurrence and tendency for development of metastasis.

DISCUSSION

The effects of postoperative radiotherapy need further investigation. Besides neurosurgery, radiotherapy should always be considered in both patients with these highly malignant tumours (WHO grade III) and in patients with partial resection or inoperable cases (WHO grade II).

Surgical management of primary spinal hemangiopericytomas: an institutional case series and review of the literature

PURPOSE

Hemangiopericytoma (HPC) is a rare tumor of the central nervous system. Primary spinal occurrence of this tumor is extremely uncommon and cases involving the intramedullary spinal cord are even more rare. The purpose of this study was to explore the clinical features, surgical strategies, outcome and pathology in a consecutive series of patients treated at a single institution.

METHODS

The authors performed a retrospective review of the clinicopathological characteristics of four patients with a pathological diagnosis of spinal HPC.

RESULTS

Four cases with intradural as well as intra/extra-medullary components were identified. Gross total resection with no recurrence at the operative site was achieved in the majority of patients with a spinal HPC. One patient had significant recurrence and eventually, succumbed to the disease.

CONCLUSION

Increased awareness of these tumors' capability to occur intradurally and intramedullarly can help surgeons accurately diagnose and choose an effective plan of care. Gross total resection of hemangiopericytomas is the mainstay of treatment and should be pursued if feasible. Histopathology is essential to the diagnosis.

Hemangiopericytomas in the Spine

BACKGROUND:

Intraspinal hemangiopericytoma (HPC) is a rare and malignant extra-axial tumor with a strong tendency to recur and metastasize. There is a paucity in the literature of large case series of patients with intraspinal HPCs.

OBJECTIVE:

We retrospectively analyzed the clinical radiological and histological features, classification, and treatment of 26 patients with HPCs in the spine.

METHODS:

Twenty-six patients with HPCs in the spine were treated at our institution between 1987 and 2010. Medical records were reviewed retrospectively to collect data on the clinical features, tumor morphology, surgical resection, recurrence, and follow-up.

RESULTS:

The 26 patients were predominantly male, and the mean age at diagnosis was 33.8 years. The intraspinal HPCs were divided into 3 types and 5 subtypes. Most of them involved the neighboring segments and/or caused bony erosion. All tumors were immunohistochemically positive for vimentin and negative for epithelial membrane antigen. All patients underwent at least 1 surgery, and most of them received postsurgical radiotherapy. The 5-year Kaplan-Meier rate of survival was 76%. The 5-year recurrence-free rate of survival was 29.4%. Only the tumor pathological grade was significantly associated with survival time and recurrence.

CONCLUSION:

High-grade tumors had a shorter survival time and recurred earlier than low-grade tumors. Surgical removal and postoperative radiotherapy are critical for the treatment of intraspinal HPCs. However, total resection may not necessary for these tumors. Stereotactic radiosurgery may be a good alternative to control the recurrent lesions.

MRS study of meningeal hemangiopericytoma and edema: a comparison with meningothelial meningioma

Intracranial hemangiopericytomas (HPCs) are rare tumors and their radiological appearance resembles that of meningiomas, especially meningothelial meningiomas. To increase the knowledge on the biochemical composition of this type of tumor for better diagnosis and prognosis, we performed a molecular study using ex vivo high resolution magic angle spinning (HR-MAS) magnetic resonance spectroscopy (MRS) perfomed on HPC and peritumoral edematous tissues. Moreover, to help in the discrimination between HPC and meningothelial meningioma we compared the ex vivo HR-MAS spectra of samples from one patient with HPC and 5 patients affected by meningothelial meningioma. Magnetic resonance imaging (MRI), in vivo localized single voxel 1H-MRS was also performed on the same patients prior to surgery and the in vivo and ex vivo MRS spectra were compared. We observed the presence of OH-butyrate, together with glucose in HPC and a low amount of N-acetylaspartate in the edema, that may reflect neuronal alteration responsible for associated epilepsy. Many differences between HPC and meningothelial meningioma were identified. The relative ratios of myo-inositol, glucose and gluthatione with respect to glutamate are higher in HPC compared to meningioma; whereas the relative ratios of creatine, glutamine, alanine, glycine and choline-containing compounds with respect to glutamate are lower in HPC compared to meningioma. These data will be useful to improve the interpretation of in vivo MRS spectra resulting in a more accurate diagnosis of these rare tumors.

Adyuvant fractionated radiotherapy after resection of intracranial hemangiopericytoma

AIM

Review of literature and adjuvant treatment in Hemangiopericytoma after complete resection.

BACKGROUND

Intracranial hemangiopericytoma (HPC) is an uncommon malignant vascular tumor arising from mesenchymal cells with pericytic differentiation. Surgery remains the mainstay treatment, and adjuvant radiation therapy appears to be appropriate for patients with high grade tumors or incomplete resection. We present our experience and review of the literature.

MATERIALS AND METHODS

We describe two cases of intracranial hemangiopericytoma located in the frontal lobe of the CNS. Both patients underwent complete tumor resection followed by adjuvant fractionated radiotherapy and completed treatment without interruptions.

RESULTS

A local recurrence was observed in one of these cases and fractionated stereotactic radiotherapy was performed. Both patients are alive and disease has been under control up to date.

CONCLUSION

The treatment of choice for intracranial hemangiopericytoma is a complete surgical resection as long as possible. Adjuvant radiotherapy of HPC can result in increased tumor control and should be considered as an effective treatment for patients with high grade or demonstrated residual tumor in the postoperative period. Salvage treatment using limited-field fractionated radiotherapy for local recurrence treatment is considered an acceptable option.

Large hemangiopericytoma associated with arteriovenous malformations and dural arteriovenous fistulae

BACKGROUND

Hemangiopericytomas are rare vascular tumors of the central nervous system. Although hemangiopericytomas have been associated with other vascular malformations, there is no report of an intracranial hemangiopericytoma found in association with multiple arteriovenous malformations and dural arteriovenous fistulae.

CASE DESCRIPTION

We present the case of an otherwise healthy 25-year-old woman who presented with a large hemangiopericytoma involving the superior sagittal sinus. The highly vascular nature of the lesion, the total occlusion of the sinus anterior to the tumor, and the presence of multiple arteriovenous malformations and dural arteriovenous fistulae complicated resection of this tumor.

CONCLUSION

To our knowledge, no prior report has described a tumor of this magnitude in association with multiple AVMs and dAVFs.

Imaging pattern of calvarial lesions in adults

Calvarial lesions often present themselves as clinically silent findings on skull radiographs or as palpable masses that may cause localized pain or soreness. This review aims to explore the radiographic, computed tomography (CT), and magnetic resonance imaging (MRI) characteristics of calvarial neoplastic, inflammatory, and congenital lesions that are common in adults in order to facilitate a structured approach to their diagnosis and limit the differential diagnosis. In addition to reviewing the literature, we reviewed the records of 141 patients of the Montreal Neurological Institute and Hospital with radiologically documented calvarial lesions between 2001 and June 2009. CT is ideal for detecting bony lesions and is helpful in precisely localizing a lesion pre-surgically. MRI is best at identifying intradiploic lesions before they affect the cortical tables and is able to establish extraosseous involvement, especially when paramagnetic contrast is employed.

Hemangiopericytomas of the skull base

Object

Intracranial hemangiopericytomas are frequently located along the dural sinuses along the skull base and represent rare, aggressive CNS neoplasms that are difficult to distinguish from meningiomas based on both imaging and gross characteristics. The authors of this study describe 3 patients with these lesions and review the pertinent literature.

Methods

Two men and 1 woman, whose median age at the time of the initial presentation was 37 years (range 20–53 years), constitute this series. They underwent multimodal treatment consisting of resection, embolization, radiation therapy, and in 1 case chemotherapy.

Results

Two of the 3 patients treated were alive after a mean follow-up of 93 months (range 4–217 months). One patient died 217 months after the initial diagnosis. The longest tumor progression–free interval after the initial or secondary resection was 43 months (range 4–84 months).

Conclusions

Hemangiopericytomas have been reclassified as mesenchymal nonmeningothelial tumors. They have an inevitable tendency to recur locally and metastasize distally. The mainstay of therapy remains an aggressive attempt to achieve gross-total resection at the initial surgery. Postoperative adjuvant radiotherapy should be offered to all patients, regardless of the degree of resection achieved. Diligent long-term follow-up is paramount as local recurrences and distal metastases can develop sometimes years after the initial treatment.