[Clinical analysis of 12 cases of solitary fibrous tumors in nasal cavity, sinuses and skull base].

Objective:To summarize and analyze the clinical manifestations, diagnosis and management and prognostic features of solitary fibrous tumor（SFT） in nasal cavity, sinus and skull base. Methods:The clinical data of 12 patients with STF from nasal cavity, sinus and cranial base admitted to the Affiliated Hospital of Qingdao University from April 2014 to January 2022 were retrospectively analyzed, including 4 patients admitted to the department of Otolaryngology head and neck surgery and 8 patients admitted to the department of skull base surgery The clinical characteristics, diagnosis, management and prognosis were analyzed. Results:Twelve patients were included in this research, including 7 males and 5 females. All patients received surgical treatment, and 4 patients also received postoperative adjuvant chemoradiotherapy. After follow-up for 12-60 months, 4 patients with adjuvant radiotherapy and chemotherapy had a good prognosis, and among 8 patients who did not receive radiotherapy and chemotherapy, 6 patients had good prognosis and 2 patients showed relapse. Four patients with a history of recurrence of SFT after surgery were admitted to our hospital for surgical treatment, in which 1 patient had relapse after surgery, and none had metastasis. Nasal cavity and sinus to skull base SFT is rare. The most effective treatment for this disease is surgical resection, and postoperative adjuvant chemoradiation and long-term follow-up can achieve a better prognosis. En bloc resection is the key to treatment success.

Immunotherapy for Solitary Fibrous Tumor (Hemangiopericytoma): A Unique Treatment Approach for a Rare Central Nervous System Tumor.

INTRODUCTION: Solitary fibrous tumors (SFTs) of the central nervous system represent a unique entity with limited data on best treatment practices. CASE REPORT: Here, we present a case of multiply recurrent central nervous system SFT treated with radiation and immunotherapy. Immunotherapy was chosen based on mutations of genes encoding DNA repair enzymes detected through next-generation sequencing of the tumor, DNA polymerase epsilon catalytic subunit ( POLE ) and mutL homolog 1. The use of radiation and immunotherapy led to slight shrinkage and no recurrence of the tumor for over 2 years. CONCLUSION: The presence of somatic DNA repair enzyme gene mutations in SFT may suggest a benefit from a combination of radiotherapy and immunotherapy. This may serve as a biomarker for guiding management in patients with this rare tumor.

Prognostic Factors of Survival for Grade 3 Solitary Fibrous Tumor/Hemangiopericytoma: A Population-Based Retrospective Surveillance, Epidemiology, and End Results Database Analysis.

INTRODUCTION: Grade 3 solitary fibrous tumor, previously known as anaplastic hemangiopericytoma, is a rare and highly malignant intracranial tumor with a limited understanding of its natural history and treatment outcomes. METHODS: We conducted a retrospective analysis using the Surveillance, Epidemiology, and End Results (SEER) database spanning 2000-2019 to evaluate the clinical characteristics and treatment modalities that influence overall survival in this tumor entity. A cohort of 249 patients with intracranial grade 3 solitary fibrous tumors was identified. Univariate and multivariable Cox proportional hazard models were employed to determine significant prognostic factors for overall survival. Kaplan-Meier models were used to visualize survival curves, and a nomogram was constructed to predict survival probabilities at 6- and 12-month following diagnosis. RESULTS: Our findings indicated that patient age (<65 years), localized or regional disease burden, surgical resection, and radiation therapy were significant predictors of better overall survival. Combination therapies showed improved survival, with surgery and radiation therapy having the most significant impact. However, chemotherapy alone or in combination did not demonstrate a significant survival benefit, likely due to the limited sample size. The nomogram provided personalized prognostic predictions based on significant clinical factors. CONCLUSIONS: These data emphasize the importance of surgical resection and radiation therapy in the management of grade 3 solitary fibrous tumors, supporting the use of combination therapies to improve overall survival in this rare and aggressive intracranial neoplasm.

Comprehensive analysis reveals potential therapeutic targets and an integrated risk stratification model for solitary fibrous tumors.

Solitary fibrous tumors (SFTs) are rare mesenchymal tumors with unpredictable evolution and with a recurrence or metastasis rate of 10-40%. Current medical treatments for relapsed SFTs remain ineffective. Here, we identify potential therapeutic targets and risk factors, including IDH1 p.R132S, high PD-L1 expression, and predominant macrophage infiltration, suggesting the potential benefits of combinational immune therapy and targeted therapy for SFTs. An integrated risk model incorporating mitotic count, density of Ki-67+ cells and CD163+ cells, MTOR mutation is developed, applying a discovery cohort of 101 primary non-CNS patients with negative tumor margins (NTM) and validated in three independent cohorts of 210 SFTs with the same criteria, and in 36 primary CNS SFTs with NTM. Compared with the existing models, our model shows significantly improved efficacy in identifying high-risk primary non-CNS and CNS SFTs with NTM for tumor progression.Our findings hold promise for advancing therapeutic strategies and refining risk prediction in SFTs.

[Research progress of intraspinal solitary fibrous tumor].

Objective: To review the research progress of intraspinal solitary fibrous tumor (SFT). Methods: The domestic and foreign researches on intraspinal SFT were extensively reviewed and analyzed from four aspects, including disease origin, pathological and radiological characteristics, diagnosis and differential diagnosis, and treatment and prognosis. Results: SFT is an interstitial fibroblastic tumor with a low probability of occurrence in the central nervous system, especially in the spinal canal. In 2016, the World Health Organization (WHO) used the joint diagnostic term "SFT/hemangiopericytoma" according to the pathological characteristics of mesenchymal fibroblasts, which can be divided into three levels according to specific characteristics. The diagnosis process of intraspinal SFT is complex and tedious. It has relatively variable imaging manifestations and specific pathological changes of NAB2-STAT6 fusion gene, which often requires differential diagnosis with neurinoma, meningioma, etc. The treatment of SFT is mainly resection, which can be assisted by radiotherapy to improve the prognosis. Conclusion: Intraspinal SFT is a rare disease. Surgery is still the main treatment. It is recommended to combine preoperative or postoperative radiotherapy. The efficacy of chemotherapy is still unclear. In the future, more studies are expected to establish a systematic diagnosis and treatment strategy for intraspinal SFT.

Solitary Fibrous Tumor: Integration of Clinical, Morphologic, Immunohistochemical and Molecular Findings in Risk Stratification and Classification May Better Predict Patient outcome.

Although solitary fibrous tumors (SFTs) have an unpredictable evolution, some specific clinicopathologic factors have been associated with the final outcome. We retrieved clinical, pathological and molecular data of 97 patients with a histological diagnosis of SFT and Signal transducer and activator of transcription 6 (STAT6) positivity. We retrospectively studied the pathological factors predictive of recurrence/metastasis and compared them with the clinical outcome. A wide immunohistochemical study and molecular analysis to detect NAB2/STAT6 gene fusion, tumor protein-53 (TP53) and/or (telomerase reverse transcriptase) TERT promotor mutation were performed. The risk of metastasis was calculated using the Demicco risk stratification system (RSS). The results were combined and examined to assess the accuracy of risk stratification and classification. The most common location was in non-extremities; 66% were located in soft tissue or subcutaneous areas and 92.8% in deep locations. On microscopic analysis, 38.1% of tumors revealed hypercellularity with a predominant patternless and/or hemangiopericytic growth pattern; 13.4% had ≥4 mitoses/10HPF; 16.5% showed necrosis, and almost half the tumors showed at least focal myxoid areas. Dedifferentiation was observed in three tumors. Immunomarker expression in SFTs was as follows: CD34 92.9%, CD99 57.1%, Bcl2 67.9%, neuroendocrine markers (at least 1) 25.7%, Desmin 14.3%, CK(AE1/AE3) 3%, Apoptotic Protease Activating Factor (APAF-1) 87% and finally Ki-67 ≥ 10% in 14.4%. The NAB2/STAT6 gene fusion was detected in 50 tumors. After a median follow-up of 90 months, 9.3% recurred, 11.3% metastasized, 10.3% died of disease and 76.2% were free of disease. TERT mutations were detected in 40.6% of the SFTs; the TP53 mutation was detected in 17%, and only 9.3% showed both mutations. According to the Demicco RSS, 6.1%, 11.3% and 82.4% of the tumors were classified as high, intermediate or low-risk of metastasis, respectively. All high-risk tumors had ≥4 mitoses/10HPF, necrosis, Ki-67 ≥ 10, HTER and/or TP53 mutation and poor evolution. The intermediate risk SFTs with worse evolution displayed the HTER mutation. Almost all low-risk tumors had a favorable evolution, although four showed at least one adverse factor (Ki-67 ≥ 10, ≥4 mitoses/10HPF or high tumor size) and had a worse evolution. An integration of clinical, morphologic, immunohistochemical and molecular findings may improve risk stratification and classification and better predict patient outcome. The unfavorable course seems to be more frequent in high-risk SFTs, although it is not exceptional in low-risk SFTs either; hence, a long-term follow-up is required independently of the assigned risk stratification score. The inclusion of molecular findings in risk stratification systems could improve the precision in the classification of SFTs, especially those of intermediate risk. Future studies will be required to determine the most effective way to incorporate molecular analyses into RSS on SFTs. The coexistence of several adverse factors such as ≥4 mitoses/10HPF, necrosis, Ki-67 ≥ 10%, mutations in HTER and/or p53 may suggest a closer clinical follow-up regardless of the histological appearance of the tumor.

Solitary fibrous tumor: molecular hallmarks and treatment for a rare sarcoma.

Solitary fibrous tumor (SFT) is a rare soft tissue sarcoma subtype which mainly affects adults in the fifth and sixth decades of life. Originally part of a spectrum of tumors called hemangiopericytomas, classification has been refined such that SFTs now represent a distinct subtype. The identification of NAB2-STAT6 fusion in virtually all SFTs has further aided to define this rare subgroup. SFTs have a spectrum of behavior from benign to malignant, with evidence suggesting risk of metastases related to age at diagnosis, extent of necrosis, mitotic rate and tumor size. The standard treatment for localized disease is surgical excision with or without radiotherapy. Retrospective and prospective evidence suggests antiangiogenic treatment is effective for unresectable disease. Further translational work is required to understand the biology driving the differential behavior and identify more effective treatments for patients with metastatic disease.

Intracranial solitary fibrous tumor/hemangiopericytoma: tumor reclassification and assessment of treatment outcome via the 2016 WHO classification.

PURPOSE: As per the 2016 World Health Organization (WHO) guidelines on the classification of central nervous system tumors, solitary fibrous tumors (SFTs) and hemangiopericytomas (HPCs) constitute a single disease entity, known as SFT/HPC. This study provides a clinical analysis of these tumors and describes the treatment outcomes of SFT/HPCs. METHODS: This retrospective study included 76 patients with histopathologically proven SFT/HPC. Reclassification according to the 2016 WHO guideline was done for patients who were diagnosed with SFT or HPC based on the 2007 WHO classification. Recurrence-free survival (RFS) and overall survival (OS) were evaluated for all patients and subgroups. RESULTS: The median follow-up period was 77.9 months. The median RFS and OS were 126.5 and 136.8 months, respectively. The 1-, 5-, 10-, and 15-year RFS rates were 93%, 72%, 40%, and 40%, respectively. The 1-, 5-, 10- and 15-year OS rates were 97%, 89%, 54%, and 35%, respectively. In multivariable analyses, stereotactic radiosurgery (SRS; p = 0.009, hazard ratio [HR] 6.986), female sex (p = 0.023, HR 1.76), and age over 45 (p = 0.037, HR 2.74) were associated with shorter RFS. Patients who underwent SRS as initial treatment had a shorter OS than that of patients who underwent primary resection (p < 0.001, HR 12.86). CONCLUSIONS: High-grade tumors tended to have worse OS and occur extracranial metastases earlier than low-grade tumors. The median RFS was not different between grade II and III tumors. Male sex, younger age, and GTR were associated with a better RFS. A history of SRS before tumor resection was associated with a shorter RFS and OS.

CD34-negative Solitary Fibrous Tumor: A Clinicopathologic Study of 25 Cases and Comparison With Their CD34-positive Counterparts.

CD34-negative solitary fibrous tumors (SFTs) are rare and have not been comprehensively studied. We retrospectively reviewed all cases of SFT confirmed with STAT6 immunohistochemistry and/or STAT6 gene fusion between 2013 and 2020 and collected pertinent clinicopathologic parameters. Of a total of 244 cases, 25 (10%) lacked CD34 expression by immunohistochemistry. Compared with CD34-positive SFT, CD34-negative SFT are more likely to arise in the head and neck area (32% vs. 24%, P=0.02) and present as metastatic disease (28% vs. 1%, P<0.0001). A significantly higher percentage of CD34-negative SFT exhibit high-grade cytologic atypia (hypercellularity, round cell or anaplastic morphology, nuclear pleomorphism, etc.) (48% vs. 22%, P=0.0073). There are no significant differences in the distributions of age, sex, tumor size, mitotic count, tumor necrosis, or risk stratification between CD34-negative and CD34-positive SFT. In addition, only 56% of CD34-negative SFT display a typical hemangiopericytoma-like vascular pattern. Special histologic features among CD34-negative SFT include prominent alternating hypercellular or fibrous and hypocellular myxoid areas with curvilinear vessels mimicking low-grade fibromyxoid sarcoma, pulmonary edema-like microcystic changes, and prominent amianthoid collagen fibers. In conclusion, compared with their CD34-positive counterparts, CD34-negative SFT is more likely to present as metastatic disease, show high-grade nuclear atypia, and lack the characteristic hemangiopericytoma-like vasculature, posing a unique diagnostic challenge. The use of STAT6 immunohistochemistry and/or molecular studies may be prudent in soft tissue tumors that appear CD34 negative and lack conventional SFT histopathologic characteristics.

Preoperative transarterial embolization of a recurrent orbital solitary fibrous tumor with significant hypervascularity: a case report.

BACKGROUND: Orbital solitary fibrous tumors (SFTs) are rare neoplasms. Recurrent, hypervascular, malignant variations of orbital SFTs have recently been noted and can present a surgical challenge. CASE PRESENTATION: We describe a case of a 53-year-old Chinese woman with a history of a resected orbital SFT. She presented with proptosis, limited eyeball movement, and visual loss in the right eye, suggestive of a recurrent SFT. Ocular examination with multimodal imaging revealed a large, nonpulsatile, noncompressible, hypervascular mass behind the eyeball. The patient underwent preoperative transarterial embolization of the main blood supply to the tumor in order to control intraoperative blood loss, followed by ocular enucleation to optimize exposure and enable complete resection of the tumor. Embolization of the right ophthalmic artery and the distal branch of the right internal maxillary artery caused an immediate, substantial reduction of vascular flow, which allowed us to enucleate the eyeball and resect the tumor with minimal blood loss and no complications. CONCLUSIONS: Our case is so far the first Chinese case of successful preoperative embolization of the main blood supply to a large, recurrent, hypervascular orbital SFT. This case also described a different surgical approach to achieve total removal of an orbital SFT without osteotomy.

Preoperative embolisation of orbital solitary fibrous tumour.

Solitary fibrous tumours (SFT) is an encompassing terminology comprising of tumours with proliferating CD34 positive specialised fibroblasts. Orbital SFTs are rare slowly progressive highly vascular neoplasms. Complete surgical excision is considered the mainstay treatment. Incomplete resection is a known risk factor for recurrence and malignant transformation. Recently preoperative embolisation of SFT has shown promising results in reducing the vascularity of these tumours rendering them amenable to complete surgical excision. Less than 10 cases of embolisation of orbital solitary fibrous tumours have been described in literature. Our patient underwent an attempted surgical excision elsewhere with significant intraoperative haemorrhage which precluded its complete excision. Herein, we report successful outcome in a case of hypervascular orbital SFT managed with preoperative embolisation, surgical resection and adjuvant radiotherapy along with a review of relevant literature.

[What's new in the management of meningeal solitary fibrous tumor/hemangiopericytoma?] / 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.

Metastatic intracranial solitary fibrous tumors/hemangiopericytomas: description of two cases with radically different behaviors and review of the literature.

Solitary fibrous tumor/hemangiopericytoma with primary tumor location in the central nervous system accounts for less than 1% of all central nervous system tumors. Despite the relatively indolent clinical course, extracranial metastases are reported in 28% of cases. In recent years, NAB2-STAT6 gene fusion has been recognized as the pathognomonic molecular feature of solitary fibrous tumor/hemangiopericytoma and STAT6 immunohistochemistry has been shown to be a sensitive and specific surrogate for the identification of the gene fusion in these patients. Here we report two cases of patients who experienced occurrence of diffuse extracranial metastases several years after successful surgery for an intracranial solitary fibrous tumor/hemangiopericytoma. In the first patient, the metastases had maintained similar histological features to the primary tumor; in contrast, in the second case, a dedifferentiation occurred with loss of expression of CD34 and Bcl-2. These different histological features were associated with radically different behaviors. Whereas the first case experienced an indolent course of the disease, the second patient had a rapid disease progression and deterioration of clinical conditions. The molecular imaging findings in these two cases and the role of functional imaging for tumor detection, disease staging and monitoring in this rare cancer are also discussed. Recurrences and metastases maintained high expression of somatostatin receptors confirmed by somatostatin receptor imaging in the first case. In contrast, in the second patient, the abrupt transition into a highly aggressive form was associated with the absence of somatostatin receptors at 111In Pentetreotide scan and intense hypermetabolism at 18F-FDG PET.

Solitary Fibrous Tumor of the Urinary Bladder Associated with Hypoglycemia: An Unusual Case of Doege-Potter Syndrome.

Solitary fibrous tumors (SFT) are rare mesenchymal tumors, mostly benign. Less than 30 cases have been described for the urinary bladder, 2 of them malignant. These lesions show infrequent clinical and radiological usual features, making the diagnosis difficult. Therefore, an immunohistochemical and morphological comprehensive study, which will provide the main prognostic factors, is necessary for histological diagnosis. The hypoinsulinemic hypoglycemia, as a paraneoplastic syndrome associated with SFTs - also known as the Doege-Potter Syndrome - is an infrequent finding, and quite incidental when located in the bladder. In order to obtain a fair oncological result, the recommended procedure for this type of tumors is surgical exeresis with negative margins, including non-standardized chemotherapy/radiotherapy as an alternative treatment.

Solitary fibrous tumor of the pineal region with delayed ectopic intracranial metastasis: A case report and review of the literature.

RATIONALE: Solitary fibrous tumors of central nervous system are rare spindle-cell mesenchymal tumors. Although most are benign in nature, malignant transformation and extracranial metastasis have been reported. Up to now, only one case of CSF dissemination was described. Here we described an extremely rare case of intracranial Solitary fibrous tumors arising from the pineal region with a delayed ectopic metastasis. PATIENT CONCERNS: A 35-year-old female presented with double vision, memory disturbance and unsteady gait was referred to our center. MRI showed an irregular mass in the pineal region. DIAGNOSES: The patient was diagnosed as pineal tumor, with unknown pathology. INTERVENTIONS: Gross total resection was achieved and the pathologic studies confirmed a solitary fibrous tumor. Thirty-nine months later local recurrence occurred and gamma-knife radiotherapy was offered. Seven months later, MRI found a metastasis in the left temporal lobe. Surgical resection was conducted and pathological analysis revealed changes in cell morphology, counts and Ki-67 level, confirmed the diagnosis of solitary fibrous tumor/hemangiopericytoma (WHO Grade III). The patient received post-operational radiotherapy. OUTCOMES: The patient was followed up for 7 months with no signs of recurrence. LESSONS: Here, we report an extremely rare case of primary solitary fibrous tumor of pineal region with delayed intracranial ectopic metastasis, together with literature review of metastatic solitary fibrous tumors. Strict surveillance is strongly recommended, considering the malignant potential of this seemingly benign disease entity. Complete resection of the tumor is the treatment of first choice and radiotherapy might be an effective adjuvant therapy for high grade SFT/HPCs.

Solitary fibrous tumor: An evolving and unifying entity with unsettled issues.

Solitary fibrous tumor (SFT) is a distinct fibroblastic neoplasm of intermediate biological potential, prototypically presenting as a pleura-associated tumor characterized by patternless proliferation of generally banal oval to spindle cells with hemangiopericytoma-like staghorn vessels in fibrocollagenous stroma. Over the past decades, the clinicopathological spectrum of SFT has been ever-expanding with the incorporation of cases exhibiting myxoid, giant cell-containing, and fat-forming histology, as well as those from extrathoracic sites, including the meninx. Atypical, frankly malignant and even dedifferentiated variants have also been recognized in a subset of SFTs. Notably, the recent groundbreaking discovery of the disease-defining NAB2-STAT6 gene fusion, resulting from intrachromosomal inversion involving 12q13.3, has largely unified tumors with the aforementioned variations. The derived immunohistochemical detection of nuclear STAT6 expression has high diagnostic value in distinguishing SFTs from histologic mimics, although some relevant pitfalls have been proposed as a precaution. NAB2-STAT6 fusions yield numerous transcript subtypes associated with the clinicopathological variations. Despite mostly following a favorable course, SFT is notoriously difficult for prognostication because of the propensity for late relapse or even metastases in 10-40% of cases, which prompts several proposed schemes incorporating age, size, mitosis, and/or necrosis as factors for risk stratification. Mitotic figures >4/10 HPFs, TERT promoter and/or TP53 mutations have been considered as variables that are better correlated with aggressiveness. Although radiotherapy and chemotherapy provide unsatisfactory responses, a better understanding of SFT tumorigenesis may pave the way for new treatment modalities. In this review, we comprehensively discuss the recent advances of SFTs in diagnostic and molecular pathology.