Hemangiopericytoma Research Articles

The role of radiotherapy in intracranial hemangiopericytoma/solitary fibrous tumors : ATurkish Society for Radiation Oncology Central Nervous System Tumors Group Study (TROD 07-008).

Intracranial hemangiopericytomas (HPC) are rare tumors. Radiotherapy (RT) is frequently performed after surgery, depending on tumor size, location, and the type of resection. Moreover, RT is preferred as an effective treatment for local recurrence and metastasis. With this multicenter study, we aimed to investigate the effectiveness of postoperative RT in intracranial HPC patients using modern RT techniques. Patients aged 16years and older who underwent RT for histologically confirmed intracranial HPC were evaluated retrospectively. Forty-four patients from 17institutions were included. Demographic characteristics of the patients, pathological findings, and prognostic factors were documented. The Kaplan-Meier method was used for local control (LC), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS). The interval for survival analyses was calculated according to the end date of RT. Univariate and multivariate analysis methods were used for factors associated with survival and recurrence. Median age was 42years (16-71) and 70% of the patients were male. The most common initial symptoms were pain (47.7%) and vision problems (15.9%). Asupratentorial location was observed in 79.5% of patients. The median maximum tumor dimension was 4.7 (1.6-14) cm. Gross total (GTR) and subtotal resection (STR) were performed in 43.2% and 47.7% of patients, respectively. Adjuvant RT commenced amedian of 6 (2-16) weeks after surgery. Postoperative RT was administered using conventionally fractionated intensity-modulated radiotherapy (IMRT) or stereotactic radiosurgery (SRS). Atotal median dose of 60(38-66) Gy in amedian of 30(19-33) fractions was used for patients treated with IMRT and atotal median dose of 24(12-25) Gy in amedian of 3(1-5) fractions was used for patients treated with SRS. Local recurrence occurred in 9patients and locoregional recurrence in 2patients at amedian of 48months (range 26-143 months) after RT. Reoperation and reirradiation were applied to 5patients, reirradiation to 4patients, and reoperation to 2patients as salvage treatments. Reirradiation was administered at amedian dose of 35 (13.5-54) Gy using amedian of 5 (1-30) fractions. At amedian follow-up of 63 (6-262) months, 5‑year LC was 68.7%, DMFS 87.2%, PFS 60.8%, and OS 95.7%. The presence of residual macroscopic tumor before RT was associated with lower LC (p = 0.01) and shorter PFS (p = 0.04). In the presence of residual tumor before RT, 5‑year LC decreased from 92.9% to 46.7%, while 5‑year PFS decreased from 81.1% to 43.5% compared to patients with GTR. The presence of postoperative tumor was associated with alower LC rate in Cox regression analyzes (p = 0.02). The hazard ratio was 6.2 (1.2-30). However, the effect of residual disease before RT on OS was not statistically significant. Adjuvant radiotherapy is performed in the majority of patients with HPC, especially in cases where GTR cannot be performed. In our study, postoperative macroscopic residual tumor was found to be the only factor affecting LC and PFS in patients undergoing adjuvant RT, but its effect on OS was not shown. This may be due to the effectiveness of reoperation and/or reirradiation in the presence of recurrence after RT.

Epithelioid solitary fibrous tumors from CNS and soft tissues: an unusual morphologic variant

BackgroundSolitary fibroous tumors (SFTs) are distinctive soft tissue tumors characterized by rearrangements of NAB2-STAT6 gene, which are associated with thin-walled, branching, “staghorn”-shaped vessels. SFTs are originally classified as a type of hemangiopericytoma (HPC). Classical SFTs are composed of spindle to ovoid cells arranged haphazardly or in fascicles. Rarely, SFTs exhibit unusual morphological variants such as fat formation, giant cells, dedifferentiation, or epithelioid variant. The epithelioid cell variant, which is composed almost entirely of epithelioid cells and arranged in solid or nest patterns, is extremely rare and frequently malignant.Case presentationIn this study, we reported three cases of epithelioid SFTs (ESFTs) located in extrathoracic sites (right lateral ventricle, right lumbar, left pelvis). All the subjects in this study were elderly, with a predominance of female patients, accounting for two out of the three cases, and only one case involved a male patient. The tumor cells were entirely composed of epithelioid cells and exhibited positive for CD34 and STAT-6 markers. Ultimately, the majority of cases (two out of three) were diagnosed as malignant SFTs.ConclusionThis study aims to enhance the awareness of ESFTs. In these cases, irrespective of the onset location, the arrangement patterns of tumor cells, such as papillary structures and the morphology of epithelial-like cells, conspicuously lack the hallmark histological characteristics of Solitary Fibrous Tumors (SFTs). Consequently, it requires differential diagnosis from a plethora of malignant neoplasms. Moreover, the elevated malignancy level of this cohort of cases poses substantial diagnostic challenges to pathologists, compounding the complexity of accurate interpretation.

Clinical outcomes of patients undergoing reoperation with solitary fibrous tumors/hemangiopericytomas and malignant progression of tumors.

The purpose of this study was to analyze the clinical outcomes and malignant progression of tumors in patients who underwent reoperation for recurrent solitary fibrous tumors (SFTs) and hemangiopericytomas (HPCs). We identified 48 patients who underwent reoperation because of tumor recurrence at Tangdu Hospital between January 2010 and December 2021 and analyzed the clinical outcomes, namely, the rate of gross total resection (GTR), progression-free survival (PFS), overall survival (OS), malignant progression of tumors and radiotherapy. The survival curves for each group were plotted using the Kaplan‒Meier method and compared using log-rank tests. Of the 48 patients (25 men and 23 women, mean age 49.5 ± 14.3 years), 25 experienced a second recurrence or metastasis, 15 of whom underwent a third surgery, and the remaining 10 patients who did not undergo surgery ultimately died after tumor progression. The median time (95% CI) to tumor recurrence was 40.0 (32.3-47.7) months after reoperation, with 3-, 5- and 10-year PFS rates of 54.6%, 29.5% and 14.8%, respectively. The median (95% CI) survival time was 70.0 (46.6-93.4) months, with 3-, 5- and 10-year survival rates of 67.9%, 55.1% and 36.7%, respectively. Among the 48 patients who underwent reoperation, 27 (56.3%) achieved GTR, and 21 (43.8%) achieved STR. Twelve patients in the GTR group (12/27, 44.4%) received radiotherapy after surgery, and 18 patients in the STR group (18/21, 85.7%) received radiotherapy. Of the 48 recurrent SFTs, 24 were classified as WHO grade 1, 14 were classified as WHO grade 2, and 10 were classified as WHO grade 3 based on 2021 WHO classification after the primary operation. After reoperation, 9 tumors developed malignant progression, including 4 WHO grade 1 tumors progressing to WHO grade 2 tumors, 1 WHO grade 1 tumor progressing to a WHO grade 3 tumor and 4 WHO grade 2 tumors progressing to WHO grade 3 tumors. GTR after reoperation was associated with better PFS and OS compared to STR. However, the PFS after the third surgery was significantly shorter than that after the second surgery, and the rate of GTR also decreased. Malignant progression may occur after second or third tumor recurrence. Furthermore, compared with WHO grade 1 SFTs, WHO grade 2 and grade 3 SFTs significantly decreased PFS, but OS did not differ among the three groups. Radiotherapy did not prolong PFS or OS in patients who underwent reoperation.

8203 A Solitary Fibrous Tumor Mimicking a Non-functional Pituitary Macroadenoma

Abstract Disclosure: L. Bernacet Rivera: None. S. Omay: None. A. Huttner: None. S.E. Inzucchi: None. Background: A solitary fibrous tumor (SFT), also known as hemangiopericytoma (HPC), is a rare subset of soft tissue tumors of mesenchymal origin. This type of tumor tends to have aggressive behavior and a high risk of recurrence. Approximately less than 1% of central nervous system (CNS) tumors have been identified as part of this subtype. Case Presentation: A 73-year-old female with medical history of primary hypothyroidism, myelodysplastic syndrome (MDS), and IgM kappa MGUS initially presented to her primary care physician for evaluation of progressive visual loss over several weeks, accompanied by worsening headaches. Ophthalmologic exam revealed bitemporal hemianopsia which prompted urgent imaging. Pituitary MRI with IV contrast revealed a solid sellar mass with suprasellar extension measuring 1.8 x 1.3 x 1.9 cm. The lesion was noted to superiorly displace the optic chiasm as well as to cause mild impingement of the anterior cerebral arteries. Patient was urgently referred to neurosurgery and endocrinology for further evaluation. Initial neuroendocrine laboratory assessment, performed at 8 am, revealed a cortisol 16.5 ug/dL, free T4 1.2 ng/dL, TSH 0.77 mIU/L, prolactin 9.9 ng/mL, IGF-1 17 ng/mL, the latter value consistent with adult growth hormone deficiency. Her LH and FSH were 4.3 mIU/mL and 12.6 mIU/mL, respectively, lower than expected for a post-menopausal woman. She underwent a transnasal transsphenoidal resection of the sellar lesion. Surgery was difficult due to the fibrous nature of the tumor, for which complete resection was not achieved. Post-operative course was complicated by thrombocytopenia due to MDS. Hormonal workup following surgery was consistent with central adrenal insufficiency, hypogonadotropic hypogonadism, and central hypothyroidism. Pathology showed densely cellular spindle cell neoplasm with a collagenous background consistent with hemangiopericytoma. She underwent fractionated radiotherapy and tumor has since remained stable in size. Her visual symptoms resolved quickly following surgery. Discussion: SFT is an aggressive mesenchymal tumor which rarely appears in the sellar region. There are no identified brain MRI findings that would suggest the nature of this tumor. As a result, endocrinologists should be aware of this rare condition while evaluating pituitary neoplasms. Presentation: 6/3/2024

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.

Hemangiopericytoma of the lacrimal sac: A rare case report and review of literature

A primary hemangiopericytoma (HPC) of the lacrimal sac in a 40-year-old patient is reported. HPCs are rare soft tissue tumors derived from the pericapillary pericytes with low malignant potential. Only 10 cases of lacrimal sac HPCs have been previously reported. Here, the authors report an additional case that presented clinically with epiphora and painless mass with no recurrence during 36 months of follow-up. The treatment of choice for this neoplasm with frequently unpredictable behavior is total excision with surrounding tissue and long-term follow-up.

A Radiomics Model for the Differentiation of Intracranial Solitary Fibrous Tumor/Hemangiopericytoma and Meningioma Based on Multiparametric Magnetic Resonance Imaging.

Although the imaging findings of intracranial solitary fibrous tumor (SFT)/hemangiopericytoma (HPC) and meningioma are similar, their treatment and prognosis are quite different. Accurate preoperative identification of these two types of tumors is crucial for individualized treatment. The aim of this study was to develop a radiomics model for the differentiation of intracranial SFT/HPC and meningioma based on multiparametric magnetic resonance imaging (mpMRI). A total of 99 patients from July 2012 to July 2018 with histologically and immunohistochemically confirmed SFT/HPC (n = 40) or meningiomas (n = 59) were retrospectively analyzed. A total of 1118 features were extracted based on its image shape, intensity and texture features. The logistic regression (LR) and multi-layer artificial neural network (ANN) classifiers were used to classify SFT/HPC and meningioma. The predictive performance was calculated using receiver operating characteristic curves (ROC). We found significant difference in terms of sex between the SFT/HPC and meningioma group (χ2= 4.829, P < 0.05), but no significant difference was found in age (P > 0.05). The most significant radiomics features included five shape and four first-order level features. For the LR classifier, the prediction accuracy of SFT/HPC was 71.0% and meningioma was 78.7%. For the ANN classifier, the prediction accuracy of SFT/HPC was 83.9% and meningioma was 80.9%. Both of the two classifiers achieved a high accuracy rate, but ANN was better. Radiomics features, especially when combined with an ANN classifier, can provide satisfactory performance in distinguishing SFT/HPC and meningioma.

Management of recurrent giant hemangiopericytoma: illustrative cases.

Hemangiopericytoma (HPC) is a rare malignancy accounting for 0.4% of intracranial tumors. HPCs are characterized by local aggressiveness, high rates of recurrence, and a tendency to metastasize to extracranial sites. These features make management of HPCs challenging, often requiring a combination of radical resection and radiation. Given their rarity, optimal treatment algorithms remain undefined. The authors report a series of four patients who underwent resection of intracranial HPC. Mean age at presentation was 49.3 years. Three patients had reoperation for progression of residual tumor, and one patient was surgically retreated for recurrence. One patient received adjuvant radiotherapy following initial resection, and three patients received adjuvant radiotherapy following resection of recurrent or residual disease. There was one death in the series. Average progression-free survival and overall survival following the index procedure were 32.8 and 82 months, respectively. Progression occurred locally in all patients, with metastatic recurrence in one patient. The current gold-standard treatment for intracranial HPC consists of gross-total resection followed by radiation therapy. This approach allows satisfactory local control; however, given the tendency for these tumors to recur either locally or distally within or outside of the central nervous system, there is a need for salvage therapies to improve long-term outcomes for patients.

Abstract 1108: The impact of adjuvant radiotherapy (ART) and survival prediction by machine learning in intracranial hemangiopericytoma (HPC)

Abstract Background: Intracranial HPC is a rare brain tumor that accounts for less than 1% of all primary central nervous system malignancies. Surgery is the primary treatment, and while radiation may reduce the risk of local recurrence, its overall effectiveness remains uncertain. Therefore, it is crucial to develop reliable predictions for personalized care and improved management. In this study, we used machine learning (ML) techniques to predict the survival of patients with intracranial HPC. Methods: Data were obtained from the Surveillance, Epidemiology, and End Results (SEER) database (2000-2019). Patients with other malignancies or lack of pathological diagnosis were excluded. T-tests and chi-square tests compared variables, while Kaplan-Meier, log-rank tests, and Cox regression identified prognostic factors for overall survival (OS) and cancer-specific survival (CSS). Patient records were randomly divided into training (80 %) and validation (20 %) sets. Univariate Cox regression and least absolute shrinkage and selection operator were used to identify the significant factors linked to survival, which were used to establish a nomogram for predicting the 3- and 5-year OS and CSS. Results: Of the 367 included patients, 121 underwent surgery and 246 underwent surgery + ART. The median survival time was 54 months. Patients who underwent surgery had 5-year OS rates of 61% and 86% for CSS, while those treated with surgery + ART had 81% and 96% survival rates, respectively. The two treatment groups showed significant differences in the OS and CSS (p&amp;lt;0.022 and p&amp;lt;0.017, respectively). Age ≥ 50 years was a poor prognostic factor for OS, whereas ART, localized stage and regional stage were good prognostic factors. No significant factors were associated with CSS. To construct the OS Nomogram, three predictors, age, stage, and treatment method, were chosen. In the training and validation sets, the C-indices are 0.799 and 0.736, respectively. The receiver operating characteristic curves (AUCs) for the 3- and 5-year OS in the training set were 0.594 and 0.617, respectively, whereas those in the validation set were 0.56 and 0.59. For the CSS nomogram, two factors, age and stage, were utilized. The C-indices for the training and validation sets are 0.814 and 0.774, respectively. In the training set, the AUCs for 3- and 5-year CSS were 0.585 and 0.605, respectively, and 0.563 in the validation set. The most important risk factor was the distant stage, while the most important protective factor was age less than 50 years. Conclusion: This study shows that ART has a significant impact on the treatment of Intracranial HPC and provides better survival outcomes. ML has been used to create prediction models to support personalized patient care. These findings provide valuable insights into the management of this rare brain tumor and the potential of data-driven approaches to improve treatment and outcomes. Citation Format: Sakhr Alshwayyat, Anas Alaa Al-Khalili, Ayah Erjan, Haya Kamal, Tala Abdulsalam, Mustafa Alshwayyat. The impact of adjuvant radiotherapy (ART) and survival prediction by machine learning in intracranial hemangiopericytoma (HPC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1108.

Clinical outcomes of solitary fibrous tumors and hemangiopericytomas and risk factors related to recurrence and survival based on the 2021 WHO classification of central nervous system tumors.

The authors aimed to explore the clinical outcomes and risk factors related to recurrence of and survival from solitary fibrous tumors (SFTs) and hemangiopericytomas (HPCs) that were reclassified according to the 2021 WHO classification of central nervous system (CNS) tumors. The authors retrospectively collected and analyzed the clinical and pathological data of SFTs and HPCs recorded from January 2007 to December 2021. Two neuropathologists reassessed pathological slides and regraded specimens on the basis of the 2021 WHO classification. The prognostic factors related to progression-free survival (PFS) and overall survival (OS) were statistically assessed with univariate and multivariate Cox regression analyses. A total of 146 patients (74 men and 72 women, mean ± SD [range] age 46.1 ± 14.3 [3-78] years) were reviewed, and 86, 35, and 25 patients were reclassified as having grade 1, 2, and 3 SFTs on the basis of the 2021 WHO classification, respectively. The median PFS and OS of the patients with WHO grade 1 SFT were 105 months and 199 months after initial diagnosis; for patients with WHO grade 2 SFT, 77 months and 145 months; and for patients with WHO grade 3 SFT, 44 months and 112 months, respectively. Of the entire cohort, 61 patients experienced local recurrence and 31 died, of whom 27 (87.1%) died of SFT and relevant complications. Ten patients had extracranial metastasis. In multivariate Cox regression analysis, subtotal resection (STR) (HR 4.648, 95% CI 2.601-8.304, p < 0.001), tumor located in the parasagittal or parafalx region (HR 2.105, 95% CI 1.099-4.033, p = 0.025), tumor in the vertebrae (HR 3.352, 95% CI 1.228-9.148, p = 0.018), WHO grade 2 SFT (HR 2.579, 95% CI 1.343-4.953, p = 0.004), and WHO grade 3 SFT (HR 5.814, 95% CI 2.887-11.712, p < 0.001) were significantly associated with shortened PFS, whereas STR (HR 3.217, 95% CI 1.435-7.210, p = 0.005) and WHO grade 3 SFT (HR 3.433, 95% CI 1.324-8.901, p = 0.011) were significantly associated with shortened OS. In univariate analyses, patients who received adjuvant radiotherapy (RT) after STR had longer PFS than patients who did not receive RT. The 2021 WHO classification of CNS tumors better predicted malignancy with different pathological grades, and in particular WHO grade 3 SFT had worse prognosis. Gross-total resection (GTR) can significantly prolong PFS and OS and should serve as the most important treatment method. Adjuvant RT was helpful for patients who underwent STR but not for patients who underwent GTR.

RADT-34. CLINICAL OUTCOMES OF LOCALISED AND METASTATIC CENTRAL NERVOUS SYSTEM HAEMANGIOPERICYTOMAS/SOLITARY FIBROUS TUMOURS – A SINGLE INSTITUTION EXPERIENCE

Abstract BACKGROUND/OBJECTIVE Central nervous system (CNS) haemangiopericytomas (HPC) or solitary fibrous tumours (SFT) are rare aggressive tumours. Surgery is the primary modality of treatment, however, often followed by postoperative radiotherapy due to high tendency for local recurrence. Although rare, extracranial metastases to several sites have been described. We aim to report our institutional experience in managing these rare tumours. METHODS Patients with central nervous system HPC/SFT who underwent surgical resection from 2012 to 2022 were included in the study. Data collected included patient demographics, tumour characteristics, treatment details (including primary surgery, radiotherapy and treatment for relapse) and clinical outcomes. RESULTS Five patients were included in this study. All were women and their mean age at diagnosis was 43 years. Four patients presented with intracranial disease and one with cervico-thoracic spine disease. All patients had undergone primary surgery and gross total resection was achieved in two patients. Two patients had grade 1, one with grade 2 and two with grade 3 HPC. Four patients received radiotherapy (median dose 60Gy) and one was on imaging surveillance after surgery. Three patients had relapsed – one with locoregional relapse only, one with distant (liver and bone) relapse and other with locoregional and distant (lung and bone). Time to relapse were 192, 39 and 120 months respectively. Stereotactic radiotherapy was used to treat local relapse in posterior fossa and dura of cervical spine, and metastatic relapse in lung with a stable radiological response. One patient with a painful destructive bone metastases was treated with palliative radiotherapy with good pain control. Four patients were alive at the time of the study, and one was lost to follow up. CONCLUSION We present our institutional experience in management of localised and metastatic HPC/SFT. Stereotactic radiotherapy could be considered an effective treatment modality for small volume relapse of HPC.

540P Impact of adjuvant radiotherapy (ART) on survival time in patients with hemangiopericytoma (HPC): A population study

540P Impact of adjuvant radiotherapy (ART) on survival time in patients with hemangiopericytoma (HPC): A population study

Head and Neck Hemangiopericytoma: A Rare Case Report and Literature Review.

Hemangiopericytomas (HPCs) are rare vascular tumors, and head and neck hemangiopericytoma (HNHPC) accounts for 11% to 16% of all HPCs, possibly occurring at any age. However, according to a recent study, HNHPC was most frequently observed in middle-aged adults and had a slight predominance of female patients. In the present case, we report the successful treatment of HNHPC.

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.

Primary intranasal perivascular wall tumors in 2 cats.

Perivascular wall tumors (PWTs) are common well-known canine mesenchymal tumors. The term PWT has not yet been applied to cats; only 2 cases of feline soft tissue hemangiopericytomas (HEPs) are available. In human medicine, sinonasal HEP-like tumor/glomangiopericytoma (SHPCL/GP) and intranasal solitary fibrous tumor (SFT) are well-known mesenchymal tumors with staghorn vasculature and low malignant potential; however, these entities have not been described in small animals. We describe here the pathologic and immunohistochemical features of 2 cases of feline intranasal mesenchymal tumors consistent with PWTs and resembling human SHPCL/GP (case 1), and human intranasal SFT (case 2). Both cats developed intranasal, unilateral, polypoid, expansile neoplasms with a mostly patternless growth of spindle cells, minimal stroma, and prominent staghorn vessels. The stroma was PAS negative, which excludes a glomus tumor. Immunohistochemistry identified diffuse vimentin and PDGFRβ expression. Case 1 was α-SMA positive (as is human SHPCL/GP); case 2 was negative (as is human intranasal SFT). Both tumors were incompletely excised, leading to recurrence in case 1. Case 2 was lost to follow up. To our knowledge, intranasal PWTs have not been reported previously in cats. The frequency of the lesions is not known, but awareness of these entities may assist in their recognition and better characterization in the future.

Solitary fibrous tumor/hemangiopericytoma of the cervical spine: A systematic review of the literature with an illustrative case.

In the WHO 2016 classification of central nervous system tumors, solitary fibrous tumors (SFT) and hemangiopericytomas (HPC) were considered part of the same category given a shared mutation. Nevertheless, since the new 2021 WHO classification, the term "hemangiopericytoma" has been retired, and SFT is considered an independent pathological entity. We reviewed the literature following preferred reporting items for systematic reviews and meta-analyses guidelines focusing on the treatment options and prognosis of patients with cervical SFT. We also present a 68-year-old female with spinal intradural extramedullary SFT complicated by diffuse extension into paravertebral tissues and muscles. We found 38 cervical SFT in the literature. Patients averaged 47.3 years of age and 47.4% were female. Typically, these lesions spanned two spinal levels resulting in cord compression and most frequently exhibited benign features (i.e., diagnosed as Grade I SFTs). Interestingly, two patients exhibited distant metastases and had initial pathology consistent with grade II SFT. SFT of the cervical spine is rare and its management varies according to the histological grade and the clinical behavior, generally warranting surgical excision and adjuvant radiation therapy and/or systemic chemotherapy.

Multidisciplinary Treatment of Liver Metastases from Intracranial SFTs/HPCs: A Report of Three Consecutive Cases.

In the 2016 WHO classification of tumors of the central nervous system, hemangiopericytomas (HPCs) and solitary fibrous tumors (SFTs) were integrated into a new entity (SFT/HPC). Metastases to bone, liver, lung, and abdominal cavity are of concern. Only 37 cases of patients with liver metastases due to intracranial SFTs/HPCs have been reported. Herein, we present our experience in the management of patients with liver metastases from intracranial SFTs/HCPs. All consecutive patients who were treated for liver metastases from intracranial SFTs/HPCs from January 2014 to December 2020 were enrolled. Overall, three patients were treated for liver metastasis from SFTs/HPCs with curative intent. Two patients with bilobar metastases at presentation required surgical resection, transarterial embolization, stereotactic radiofrequency ablation (SRFA) and systemic therapy. One patient with a singular right liver lobe metastasis was treated with SRFA alone. This patient shows no evidence of liver metastases 39 months following diagnosis. Of the two patients with bilobar disease, one died 89 months following diagnosis, while one is still alive 73 months following diagnosis. Long-term survival can be achieved using a multimodal treatment concept, including surgery, loco-regional and systemic therapies. Referral to a specialized tertiary cancer center and comprehensive long-term follow-up examinations are essential.

Endoscopic endonasal resection of two rare cases of hemangiopericytomas invading the cavernous sinus and literature review

Hemangiopericytomas (HPCs) invading the cavernous sinus (CS) are extremely rare invasive tumors that have a great propensity for local recurrence. To date, only eight cases have been reported in the literature. Owing to the abundant vascular supply of HPCs, intracavernous bleeding and important blood vessels and nerves passing through the CS, it is very difficult and challenging for neurosurgeons to completely resect HPCs. Here, we report two cases of HPCs invading the CS and introduce their clinical manifestations, imaging findings, surgical approaches and histopathological features in detail. We have implemented the surgery by the endoscopic transpterygoid transcavernous approach (ETPTCa) for the two patients, and one patient has undergone gross total resection (GTR) and another has undergone subtotal resection (STR) and postoperative stereotactic radiosurgery (SRS). The ETPTCa may serve as a viable option to facilitate HPCs resection. Radiotherapy is helpful in prolonging progression-free survival (PFS) following STR of the tumor.

Cerebellar Hemangiopericytoma: A Case Report and Literature Review

Background: Haemangiopericytoma (HPC) is a rare mesenchymal tumour. It was first described in 1942 by A.P. Stout and M. Murray. It represents less than 1% of intracranial tumours. Its location in the cerebellopontine angle and its appearance on CT or MRI can be misleading and lead to a false diagnosis of acoustic neuroma or meningioma. Hemangiopericytoma is characterised by its malignant potential, high rate of recurrence and distant metastases, justifying wide surgical removal and additional radiotherapy.

Intracranial Solitary Fibrous Tumor: A "New" Challenge for PET Radiopharmaceuticals.

Solitary fibrous tumor (SFT) of the central nervous system, previously named and classified with the term hemangiopericytoma (HPC), is rare and accounts for less than 1% of all intracranial tumors. Despite its benign nature, it has a malignant behavior due to the high rate of recurrence and distant metastasis, occurring in up to 50% of cases. Surgical resection of the tumor is the treatment of choice. Radiotherapy represents the gold standard in the case of post-surgery residual disease, relapse, and distant metastases. In this context, imaging plays a crucial role in identifying the personalized therapeutic decision for each patient. Although the referring imaging approach in SFT is morphologic, an emerging role of positron emission tomography (PET) has been reported in the literature. However, there is still a debate on which radiotracers have the best accuracy for studying these uncommon tumors because of the histological or biological heterogeneity of SFT.