A Hemangiopericytoma in the External Auditory Canal: A Rare Clinical Presentation and Management.

Hemangiopericytomas (HPCs) are rare vascular tumors originating from pericytes, with a predilection for the musculoskeletal system and occasional occurrence in the head and neck region. HPCs arising in the external auditory canal (EAC) are exceptionally rare, making their diagnosis and management a clinical challenge. A 71-year-old male presented with a six-month history of a painless, progressively enlarging mass in his right EAC, accompanied by tinnitus and hearing loss. Physical examination revealed a mobile, reddish mass in the concha of the left auricle, nearly occluding the EAC. Contrast-enhanced computed tomography of the temporal bone demonstrated a heterogeneously enhancing mass with erosion of adjacent structures. Histopathological examination and immunohistochemistry confirmed the diagnosis of an HPC. The tumor was surgically excised, and the patient underwent adjuvant radiotherapy. Over a two-year follow-up period, no recurrence was observed. This case highlights the rarity of HPCs in the EAC and underscores the importance of considering this diagnosis in patients presenting with atypical EAC masses. A multidisciplinary approach, including surgical excision and radiotherapy, is crucial for achieving favorable outcomes and reducing the risk of recurrence. Long-term follow-up is essential due to the potential for late recurrence.

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

OBJECTIVE: 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). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Solitary Fibrous Tumour of the Mesentery: An Uncommon Site for a Rare Tumour.

Solitary fibrous tumour (SFT), a unique spindle-cell neoplasm, was first identified in the pleura and was earlier named as haemangiopericytoma. The origin of SFT is not well established; however, it has recently been described as a mesenchymal neoplasm, probably arising from the ubiquitous dendritic interstitial cells. SFTs are predominantly benign tumours with a low risk of malignant transformation and are commonly seen in the intrathoracic region, seldom involving extrapleural locations. Although SFTs are extensively documented in medical literature, those originating in the mesentery are extremely uncommon. Here, we report an extremely rare case of a 31-year-old woman who presented with abdominal pain and was later diagnosed with SFT of the mesentery of the sigmoid colon based on histomorphology and immunohistochemistry studies. This case highlights that, although uncommon, such differential diagnoses need to be considered in cases of abdominopelvic swellings and must be differentiated from their histological mimickers for better patient care.

A case of lumbar spinal solitary fibrous tumor or hemangiopericytomas.

Background: Solitary fibrous tumors (SFTs) account for 3.7% of all soft-tissue sarcomas, with an annual incidence of 0.35/100,000 individuals. Notably, although 20% involve the central nervous system, only one in 10 occurs in the spine versus the brain. Case Description: A 46-year-old female presented with 18 months of left lower extremity sciatica. On examination, she had a 60° limitation of straight leg raising but was otherwise neurologically intact. The lumbar magnetic resonance revealed a dumbbell tumor at the L4-L5 level filing the canal, causing cauda equina compression and extending into the left L45 foramen. The patient successfully underwent a L4 left hemi-laminectomy for tumor resection. The postoperative World Health Organization (WHO) histopathology was consistent with a SFT/WHO Grade I hemangiopericytoma (HPC). Conclusion: A 46-year-old female with a lumbar L4 SFT with the left L45 foraminal extension successfully underwent a left hemilaminectomy for GTR of an SFT/WHO Grade I HPC.

Meningeal solitary fibrous tumor cell states phenocopy cerebral vascular development and homeostasis.

BACKGROUND: Meningeal solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms that are associated with local recurrence and hematogenous metastasis. The cell states and spatial transcriptomic architecture underlying the unique clinical behavior of meningeal SFTs are unknown. METHODS: Single-cell (n=4), spatial (n=8), and bulk RNA sequencing (n=22) was used to define the cell states and spatial transcriptomic architecture of meningeal SFTs across histological grades and in patient-matched pairs of primary/recurrent or intracranial/metastatic samples. Immunofluorescence, immunohistochemistry, and comparison of single-cell types to meningiomas, or to cerebral vascular development or homeostasis, were used for validation. RESULTS: Here we show meningeal SFTs are comprised of regionally distinct gene expression programs that resemble cerebral vascular development or homeostasis. Single-cell trajectory analysis and pseudotemporal ordering of single-cells suggest that meningeal SFT cell fate decisions are dynamic and interchangeable. Cell-cell communication analyses demonstrate receptor-ligand interactions throughout the meningeal SFT microenvironment, particularly between SFT cells, endothelia, and immature neurons. Direct comparison of single-cell transcriptomes from meningeal SFTs versus meningiomas shows that SFT cells are enriched in expression of endothelial markers while meningiomas cells are enriched in expression of mural cells markers. Meningeal SFT spatial transcriptomes show regionally distinct intratumor heterogeneity in cell states, gene expression programs, and cell-cell interactions across WHO histological grades and in patient-matched pairs of primary/recurrent or intracranial/metastatic samples. CONCLUSIONS: These results shed light on pathways underlying meningeal SFT biology in comparison to other central nervous system tumors and provide a framework for integrating single-cell, spatial, and bulk RNA sequencing data across human cancers and normal tissues.

Breaking New Ground: Unraveling Sinonasal Hemangiopericytoma Through a Rare Case Series on Endoscopic Excision and Postoperative Monitoring.

Hemangiopericytoma is a rare vascular neoplasm derived from pericytes, with uncertain malignant potential. It mainly occurs in the retroperitoneum and lower extremities, with a lower incidence in the head and neck region and nasal cavity. Diagnosis is aided by histopathological examination and immunohistochemistry. Surgical excision is the preferred treatment, with different approaches depending on tumour size. Endoscopic excision is suitable for small tumours, while larger ones may require external approaches. The recurrence rate is approximately 25%, emphasizing the importance of long-term follow-up. Our study aims to discuss a rare series of sinonasal hemangiopericytoma cases, their clinical presentation, and their management. In this study, we are discussing the prospective study of six cases of sinonasal hemangiopericytoma that were presented to a tertiary hospital, from June 2017 to June 2023, with complaints of nasal obstruction and bleeding episodes. They were assessed with a detailed history, blood investigations, radiological investigations, and diagnostic nasal examination, and underwent endoscopic surgical excision of the nasal mass, with the diagnosis confirmed by histopathological examination and immunohistochemistry. All cases were followed up for 1 year postoperatively, except one case which missed follow-up after 6 months and with no postoperative complications and recurrences. All six cases came with complaints of nasal obstruction and bleeding from the nasal cavity. All six cases underwent endoscopic surgical excision of the tumour and were followed for 1 year in five cases; one case missed follow-up after 6 months of postoperative follow-up, but no recurrence was noted in all the cases. For small-sized hemangiopericytoma tumours, endoscopic excision offers benefits such as improved visualization, easy resection, preservation of the normal anatomical structure, and maintenance of physiological function in the sinonasal cavities. With a recurrence rate of approximately 25%, surgical excision and long-term follow-up play essential roles in successful tumour management.

Intracranial solitary fibrous tumors: Clinical, radiological, and histopathological insights along with review of literature.

BACKGROUND: Intracranial solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms, often challenging to diagnose due to their resemblance to meningiomas and other central nervous system tumors. While advancements in molecular genetics have aided in classification, diagnostic nuances and optimal management strategies remain areas of interest. MATERIALS AND METHODS: This retrospective study analyzed 11 cases of intracranial SFTs treated at a neurosurgical centre in India between February 2020 and January 2024. Clinical data, radiological findings, histopathological features, and follow-up details were reviewed. Immunohistochemistry, particularly STAT6, facilitated diagnosis confirmation. RESULTS: The median age of presentation was 32 years, with a male predominance. Headache was the most common presenting symptom, often leading to misdiagnosis as meningiomas on radiological imaging. Histologically, SFTs exhibited spindle to ovoid cells with staghorn vessels and collagenized stroma, posing challenges in differential diagnosis. WHO grading predominantly revealed grade 1 tumors, though recurrence occurred, emphasizing the importance of long-term follow-up. Immunohistochemistry, particularly STAT6, played a pivotal role in distinguishing SFTs from other entities. CONCLUSION: Intracranial SFTs present diagnostic challenges due to overlapping features with other tumors, warranting a comprehensive approach integrating clinical, radiological, and histopathological findings. Immunohistochemistry, particularly STAT6, emerges as a valuable diagnostic tool. Long-term follow-up is essential for monitoring recurrence and potential malignant transformation. Further research is needed to delineate optimal treatment strategies, including the role of radiotherapy in SFT management.

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.

Rare Encounter: Giant Hemangiopericytoma of Thigh in a Young Male.

A rare tumor called hemangiopericytoma develops from the pericytes, the cells that surround blood vessels. They frequently grow slowly and might be asymptomatic initially. Although they can develop anywhere in the body, these tumors are most frequently found in the head, pelvis, and legs. This uncommon tumor originates in soft tissues like fat, muscles, tendons, nerves, blood vessels, and other fibrous tissues. The tumor in adolescence can be benign or malignant; it frequently develops in the bones but has the potential to metastasize to the lungs. Imaging tests, such as MRIs or CT scans, are commonly used in diagnosis to determine the location and size of the tumor. We present a case of a 23-year-old male who complained of swelling in his left thigh that had persisted for two years. He underwent multiple biopsies which were inconclusive until wide local excision of the swelling was done. On histopathology, the excised tumor was suggestive of hemangiopericytoma. The patient was advised of radiotherapy for completion of the treatment.

Sellar hemangiopericytoma masquerading as pituitary adenoma: an overlooked intriguing case study unveiling a rare surgical conundrum.

Hemangiopericytoma (HPC) constitutes less than 1% of all primary central nervous system tumors. It is a vascular neoplasm with potential malignancy that, in rare instances, manifests as a primary lesion within the brain. Typically, it originates from the meninges. Here, we describe an exceptionally uncommon sellar region solitary fibrous tumor/hemangiopericytoma (SFT/HPC) that mimicked a nonfunctional pituitary adenoma. Case presentation: A 54-year-old male was referred to our hospital due to progressive blurred vision in the left eye over the past year. A homogeneous iso-dense extra-axial intrasellar round mass with extension into the suprasellar region, mainly on the left side, along with bony erosion and osteolysis around the sellar region, was observed on a brain computed tomography (CT) scan. Brain magnetic resonance imaging (MRI) revealed a well-defined 251,713 mm mass with iso-signal on T1-weighted images and hypersignal on T2-weighted images, originating from the pituitary gland within the sella turcica. The mass avidly enhanced following Gadolinium injection and adhered to both carotid arteries without vascular compression or invasion. It extended to the suprasellar cistern and compressed the optic chiasm. The diagnosis was nonfunctional pituitary macroadenoma, leading to the decision for Endoscopic Trans-Sphenoidal Surgery (ETSS). A non-sustainable, soft, grayish mass was grossly and totally resected during the operation. Subsequently, there was a significant improvement in visual acuity during the early postoperative period. Histopathologic examination confirmed hemangiopericytoma (WHO grade II). Conclusion: Due to its malignant nature, hemangiopericytoma should be included in the differential diagnosis of a sellar mass, both from a clinical and morphological perspective.

Solitary Fibrous Tumor With an Acute Subdural Hematoma: A Case Report and Review of the Literature.

Solitary fibrous tumor (SFT) is a rare interstitial tumor that originates from various soft tissues, and SFTs occurring within the cranium are extremely rare. While intracranial SFTs with cerebral hemorrhage or subarachnoid hemorrhage have been reported, there have been no reports of intracranial SFTs causing subdural hematoma. In this case, we report on an intracranial SFT accompanied by a subdural hematoma. A 29-year-old female was emergently transported due to the sudden onset of persistent headache and vomiting that began the night before. CT and MRI imaging revealed a hemorrhagic tumor under the tentorium and an acute subdural hematoma extending along the tentorium. The excised tumor was diagnosed as an SFT through histopathological examination. After undergoing radiation therapy, no recurrence has been observed. This is the first case report of an SFT accompanied by a subdural hematoma, and it is vital to recognize that SFTs can be associated with subdural hematomas for proper diagnosis and treatment planning.

Parasagittal meningeal hemangiopericytoma/solitary fibrous tumor: Two case reports and a literature review.

Background: Solitary fibrous tumor/meningeal hemangiopericytoma (SFT/M-HPC) is a rare neoplasm which accounts for around 1% of the intracranial masses. This pathology has a high risk for recurrence and metastasis to distant locations such as the liver, lungs, and bones. Precise diagnosis necessitates detailed histopathological examination. Case Description: We present two case reports of SFT/M-HPC. The first case is a 44-year-old female who presented with headache, nausea, vomiting, and frontal ataxia for several months. Imaging findings showed a large parasagittal extra-axial mass with compression of the frontal horns of both lateral ventricles. She underwent gross total resection with an uncomplicated postoperative period. The patient had no recurrent tumors or distal metastases in the follow-up period of 5 years. The second case is a 48-year-old male who presented with right-sided hemianopsia and hemiparesis. Computed tomography (CT) scans revealed a large parieto-occipital extra-axial mass with superior sagittal sinus engulfment and dislocation of the interhemispheric fissure. He underwent gross total resection with an uncomplicated postoperative period. Six years later, he presented with right-sided weakness. CT scan showed a multifocal recurrent mass at the previous location. He underwent subtotal resection with an uncomplicated postoperative period. Conclusion: SFT/M-HPC should be considered when presented with a meningioma-like tumor mass on preoperative imaging. Immunohistochemical study is crucial for the correct diagnosis. Strict long-term follow-up examinations and regular magnetic resonance imaging scans are key to preventing the appearance of metastases and large recurrent masses.

Case Report of Rare Solitary Fibrous Tumour of Nape of Neck with Review of Literature.

Solitary fibrous tumor (SFT) is a rare mesenchymal tumor with an indolent course but variable metastatic potential. Less than 50 cases of neck SFTs have been documented since 1991. We present a case report of rare presentations of SFT of nape of neck typifying the hypercellular variant of SFT (hemangiopericytoma) with challenges in treatment. Patient underwent excision and was subjected to adjuvant radiation. We concluded that SFT though a rare diagnosis should be considered while dealing with soft tissue tumors and multi-disciplinary pre-operative planning is must to avoid complications and recurrence. Surgical excision remains treatment of choice, but long follow-up is must.

STAT6-targeting antisense oligonucleotides against solitary fibrous tumor.

Solitary fibrous tumor (SFT) is a rare, non-hereditary soft tissue sarcoma thought to originate from fibroblastic mesenchymal stem cells. The etiology of SFT is thought to be due to an environmental intrachromosomal gene fusion between NGFI-A-binding protein 2 (NAB2) and signal transducer and activator protein 6 (STAT6) genes on chromosome 12, wherein the activation domain of STAT6 is fused with the DNA-binding domain of NAB2 resulting in the oncogenesis of SFT. All NAB2-STAT6 fusion variations discovered in SFTs contain the C-terminal of STAT6 transcript, and thus can serve as target site for antisense oligonucleotides (ASOs)-based therapies. Indeed, our in vitro studies show the STAT6 3' untranslated region (UTR)-targeting ASO (ASO 993523) was able to reduce expression of NAB2-STAT6 fusion transcripts in multiple SFT cell models with high efficiency (half-maximal inhibitory concentration: 116-300 nM). Encouragingly, in vivo treatment of SFT patient-derived xenograft mouse models with ASO 993523 resulted in acceptable tolerability profiles, reduced expression of NAB2-STAT6 fusion transcripts in xenograft tissues (21.9%), and, importantly, reduced tumor growth (32.4% decrease in tumor volume compared with the untreated control). Taken together, our study established ASO 993523 as a potential agent for the treatment of SFTs.

An Unexpected Finding of an Aggressive Pleural Hemangiopericytoma/Solitary Fibrous Tumor in a Patient With Recurrent Meningioma: A Case Report.

Pleural hemangiopericytoma/solitary fibrous tumor (HPC/SFT) is a rare form of mesenchymal tumor arising from pericytes, which predominantly occurs intrathoracically. HPC/SFT can be suspected on imaging, but radiographic features are non-specific. Therefore, histological confirmation remains the gold standard. Due to the rarity of the tumor, specific anatomical pathological expertise is necessary to make the diagnosis, which is not available in every hospital. Here, we report the case of a 51-year-old female with a medical history of recurrent meningiomas. A chest CT scan revealed extensive subpleural soft tissue lesions in the left hemithorax with histological characteristics suggestive of a pleural malignancy. A specialized analysis of the sample led to the final diagnosis of HPC/SFT. Unfortunately, in the meantime, the patient's condition worsened rapidly, and she passed away before the final diagnosis was made and any decisions about therapeutic options were taken. In our case, we want to highlight the importance of having knowledge about the existence of this type of tumor in order to make the correct diagnosis in a timely manner.

Management of recurrent giant hemangiopericytoma: illustrative cases.

BACKGROUND: 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. OBSERVATIONS: 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. LESSONS: 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.

Efficacy and toxicity of photon, proton, and carbon ion radiotherapy in the treatment of intracranial solitary fibrous tumor/hemangiopericytoma.

BACKGROUND: Solitary fibrous tumors (SFT) of the central nervous system are rare and treatment options are not well established. The aim of this study was to evaluate the clinical outcomes of radiotherapy (RT) and re-radiotherapy (re-RT) for de novo intracranial SFT and recurrent intracranial SFT. METHODS: This retrospective study analyzed efficacy and toxicity of different RT modalities in patients who received radiotherapy (RT) for intracranial SFT at Heidelberg University Hospital between 2000 and 2020 following initial surgery after de novo diagnosis ("primary group"). We further analyzed the patients of this cohort who suffered from tumor recurrence and received re-RT at our institution ("re-irradiation (re-RT) group"). Median follow-up period was 54.0 months (0-282) in the primary group and 20.5 months (0-72) in the re-RT group. RT modalities included 3D-conformal RT (3D-CRT), intensity-modulated RT (IMRT), stereotactic radiosurgery (SRS), proton RT, and carbon-ion RT (C12-RT). Response rates were analyzed according to RECIST 1.1 criteria. RESULTS: While the primary group consisted of 34 patients (f: 16; m:18), the re-RT group included 12 patients (f: 9; m: 3). Overall response rate (ORR) for the primary group was 38.3% (N = 11), with 32.4% (N = 11) complete remissions (CR) and 5.9% (N = 2) partial remissions (PR). Stable disease (SD) was confirmed in 5.9% (N = 2), while 41.2% (N = 14) experienced progressive disease (PD). 14% (N = 5) were lost to follow up. The re-RT group had 25.0% CR and 17.0% PR with 58.0% PD. The 1-, 3-, and 5-year progression-free survival rates were 100%, 96%, and 86%, respectively, in the primary group, and 81%, 14%, and 14%, respectively, in the re-RT group. Particle irradiation (N = 11) was associated with a lower likelihood of developing a recurrence in the primary setting than photon therapy (N = 18) (OR = 0.038; p = 0.002), as well as doses ≥ 60.0 Gy (N = 15) versus < 60.0 Gy (N = 14) (OR = 0.145; p = 0.027). Risk for tumor recurrence was higher for women than for men (OR = 8.07; p = 0.014) with men having a median PFS of 136.3 months, compared to women with 66.2 months. CONCLUSION: The data suggests RT as an effective treatment option for intracranial SFT, with high LPFS and PFS rates. Radiation doses ≥ 60 Gy could be associated with lower tumor recurrence. Particle therapy may be associated with a lower risk of recurrence in the primary setting, likely due to the feasibility of higher RT-dose application.

Conditional survival analysis and dynamic survival prediction for intracranial solitary-fibrous tumor/hemangiopericytoma.

BACKGROUND: As the form of World Health Organization Central Nervous System (WHO CNS) tumor classifications is updated, there is a lack of research on outcomes for intracranial combined solitary-fibrous tumor and hemangiopericytoma (SFT/HPC). This study aimed to explore conditional survival (CS) pattern and develop a survival prediction tool for intracranial SFT/HPC patients. METHODS: Data of intracranial SFT/HPC patients was gathered from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute. The patients were split into training and validation groups at a 7:3 ratio for our analysis. CS is defined as the likelihood of surviving for a specified period of time (y years), given that the patient has survived x years after initial diagnosis. Then, we used this definition of CS to analyze the intracranial SFT/HPC patients. The least absolute shrinkage and selection operator (LASSO) regression and best subset regression (BSR) were employed to identify predictive factors. The Multivariate Cox regression analysis was applied to establish a novel CS-based nomogram, and a risk stratification system was developed using this model. RESULTS: From the SEER database, 401 patients who were diagnosed with intracranial SFT/HPC between 2000 and 2019 were identified. Among them, 280 were included in the training group and 121 were included in the internal validation group for analysis. Our study revealed that in intracranial SFT/HPC, 5-year survival rates saw significant improvement ranging from 78% at initial diagnosis to rates of 83%, 87%, 90%, and 95% with each successive year after surviving for 1-4 years. The LASSO regression and BSR identified patient age, tumor behavior, surgery and radiotherapy as predictors of CS-based nomogram development. A risk stratification system was also successfully constructed to facilitate the identification of high-risk patients. CONCLUSION: The CS pattern of intracranial SFT/HPC patients was outlined, revealing a notable improvement in 5-year survival rates after an added period of survival. Our newly-established CS-based nomogram and risk stratification system can provide a real-time dynamic survival estimation and facilitate the identification of high-risk patients, allowing clinicians to better guide treatment decision for these patients.