Successful multimodal management of central nervous system solitary fibrous tumor: A case report.

Solitary fibrous tumors (SFTs) are rare neoplasms that can occur in various locations, including the central nervous system (CNS). We present a case report of a 47-year-old male patient with an intracranial SFT who underwent subtotal resection followed by adjuvant radiotherapy. The patient initially presented with chronic left temporal headache and was diagnosed with an intra-axial double-component mass in the left temporoparietal lobe. Histopathological examination confirmed the diagnosis of SFT, and immunohistochemical staining demonstrated positivity for CD34, Bcl-2, and STAT6. Following the incomplete resection, the patient received adjuvant radiotherapy using volumetric modulated arc therapy (VMAT) technique. During radiotherapy, the patient experienced a spontaneous encephalocele rupture but recovered without complications. One year postradiotherapy, the patient showed no recurrence of symptoms or radiological evidence of tumor recurrence. This case highlights the challenges in the diagnosis and management of CNS SFTs and suggests that subtotal resection followed by adjuvant radiotherapy may be an effective treatment approach in achieving favorable outcomes for these rare neoplasms.

Demographic and Clinical Characteristics of Malignant Solitary Fibrous Tumors: A SEER Database Analysis.

BACKGROUND/OBJECTIVES: Solitary fibrous tumors (SFTs) represent a rare mesenchymal malignancy that can occur anywhere in the body. Due to the low prevalence of the disease, there is a lack of contemporary data regarding patient demographics and cancer-control outcomes. METHODS: Within the SEER database (2000-2019), we identified 1134 patients diagnosed with malignant SFTs. The distributions of patient demographics and tumor characteristics were tabulated. Cumulative incidence plots and competing risks analyses were used to estimate cancer-specific mortality (CSM) after adjustment for other-cause mortality. RESULTS: Of 1134 SFT patients, 87% underwent surgical resection. Most of the tumors were in the chest (28%), central nervous system (22%), head and neck (11%), pelvis (11%), extremities (10%), abdomen (10%) and retroperitoneum (6%), in that order. Stage was distributed as follows: localized (42%) vs. locally advanced (35%) vs. metastatic (13%). In multivariable competing risks models, independent predictors of higher CSM were stage (locally advanced HR: 1.6; metastatic HR: 2.9), non-surgical management (HR: 3.6) and tumor size (9-15.9 cm HR: 1.6; ≥16 cm HR: 1.9). CONCLUSIONS: We validated the importance of stage and surgical resection as independent predictors of CSM in malignant SFTs. Moreover, we provide novel observations regarding the independent importance of tumor size, regardless of the site of origin, stage and/or surgical resection status.

Systemic metastasis in malignant solitary fibrous tumor of the liver: two case reports and literature review.

Solitary fibrous tumor of the liver (SFTL) is an exceptionally rare mesenchymal tumor, with only 117 cases reported in the literature. While most SFTs are benign, some exhibit malignant behavior, including local recurrence and metastasis. This report presents two cases of SFTL with systemic metastases, both involving prior intracranial tumors. The first case, a 52-year-old woman, discovered a liver mass incidentally during a routine physical exam. Subsequent investigations revealed potential bone metastasis, and biopsy confirmed SFT. She received two TACE procedures, anlotinib targeted therapy, and radiotherapy for the iliac bone lesion, resulting in stable disease with reduction in lesion size. The second case, a 46-year-old man, presented with multiple liver, pelvic, and lung lesions following pelvic tumor resection, with pathology confirming SFT. He was treated with long-term anlotinib therapy, CyberKnife for hepatic, lung, and pelvic lesions, and radiofrequency ablation for hepatic lesions. Postoperative recovery was uneventful, with no tumor progression on follow-up. SFTL presents with atypical clinical and imaging features, and diagnosis requires pathological and genetic confirmation. Radical resection is preferred for solitary tumors, while comprehensive treatment, including surgery and long-term follow-up, is essential for cases with recurrence or metastasis.

Central nervous system solitary fibrous tumors: Case series in accordance with the WHO 2021 reclassification. Framework for patient surveillance.

PURPOSE: Solitary fibrous tumors (SFTs) are a rare type of mesenchymal tumors. The World Health Organization reclassified SFTs in 2021. Currently, guidelines concerning treatment and follow-up are lacking. We performed a retrospective case series with reclassification of SFTs, according to the most recent WHO classification, to explore tumor-behavior. The purpose is to build a framework for long-term patient surveillance. METHODOLOGY: A retrospective case study was performed according to the PROCESS guidelines. Inclusion criteria were: patients operated on between 2013 and 2023 in two neurosurgical centers with the diagnosis of 'hemangiopericytoma' or SFT on histopathological stains. Patients were excluded if the original stains of the primary tumor were unavailable. The following demographic, radiologic and therapeutic parameters were included in the review: age, sex, original and reclassified anatomopathological diagnosis, location, extent of resection, use of postoperative radiotherapy, location of and time to recurrence, location of-and time to metastasis, and survival. Histological material was re-examined by experienced neuropathologists. RESULTS: Ten patients were identified with a solitary fibrous tumor of the central nervous system (CNS) (three females) between 2013 and 2023. Age at diagnosis ranged from 38 up to 81. Eight patients were treated by gross total resection (GTR) and postoperative radiotherapy (RT) was applied in five cases. Initial WHO grading consisted of three grade I, two grade II, and six grade III lesions. Reclassification according to the WHO 2021 classification of CNS tumors resulted in seven reclassifications, all towards a lower grade. Four patients showed local recurrence, six to eight years after diagnosis, and five patients developed systemic metastases, nine to 13 years after diagnosis. DISCUSSION: Although rare, SFT should be included in the differential diagnosis of intracranial tumors with extra-axial growth patterns. The current histological grade according to the WHO 2021 does not seem to account for local recurrence rate or systemic metastasis. When a solitary fibrous tumor is presumed, gross total resection is the recommended treatment. Lifelong patient follow-up is necessary due to the risk of delayed recurrence and distant metastasis, even after gross-total resection. We would advocate for the use of CT thorax-abdomen or full body PET in the detection of systemic metastases at diagnosis and during follow-up, however optimal intervals remain unclear.

Epigenomic and transcriptomic profiling of solitary fibrous tumors identifies site-specific patterns and candidate genes regulated by DNA methylation.

Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm which can arise at any anatomic site and is characterized by recurrent NAB2::STAT6 fusions and metastatic progression in 10-30%. The cell of origin has not been identified. Despite some progress in understanding the contribution of heterogeneous fusion types and secondary mutations to SFT biology, epigenetic alterations in extrameningeal SFT remain largely unexplored, and most sarcoma research to date has focused on the use of methylation profiling for tumor classification. We interrogated genome-wide DNA methylation in 79 SFTs to identify informative epigenetic changes. RNA-seq data from targeted panels and data from the Cancer Genome Atlas (TCGA) were used for orthogonal validation of selected findings. In unsupervised clustering analysis, the top 500 most variable CpGs segregated SFTs by primary anatomic site. Differentially methylated genes (DMGs) associated with primary SFT site included EGFR, TBX15, multiple HOX genes and their cofactors EBF1, EBF3, and PBX1, as well as RUNX1 and MEIS1. Of the 20 DMGs that were interrogated on the RNA-seq panel, twelve were significantly differentially expressed according to site. However, with the exception of TBX15, most of these also showed differential expression according to NAB2::STAT6 fusion type, suggesting that the fusion oncogene contributes to transcriptional regulation of these genes. Transcriptomic data confirmed an inverse correlation between gene methylation and the expression of TBX15 in both SFT and TCGA sarcomas. TBX15 also showed differential mRNA expression and 5' UTR methylation between tumors located in different anatomic sites in TCGA data. In all analyses, TBX15 methylation and mRNA expression retained the strongest association with tissue of origin in SFT and other sarcomas, suggesting a possible marker to distinguish metastatic tumors from new primaries without genomic profiling. Epigenetic signatures may further help to identify SFT progenitor cells at different anatomic sites.

Challenges in the Management of Recurrent CNS Solitary Fibrous Tumors: A Case Report.

Solitary fibrous tumors (SFTs) of the central nervous system (CNS) are rare mesenchymal neoplasms with diverse histological characteristics ranging from benign to malignant. Their higher chance for metastasis and recurrence poses significant diagnostic and therapeutic challenges. In this study, we present a 53-year-old female with a recurrent SFT of the cervical spine that was diagnosed initially 12 years ago. The patient underwent repeated surgical resections including laminectomy and gamma knife radiosurgery, as well as temozolomide, bevacizumab, and pazopanib therapy. Despite these interventions, she experienced continuous disease progression, with the cancer spreading to vital CNS locations. This study demonstrates the locally invasive nature of CNS SFTs and their complicated treatments involving surgical excision, radiotherapy, and systemic chemotherapy. This study highlights the need for new therapeutic approaches, as the existing methods fall short in meeting all the requirements and continue to lag in targeted therapy research for CNS SFTs. Consequently, it is important to develop individualized treatment strategies for patients affected by such difficult conditions.

Possible Genetic Links Between Solitary Fibrous Tumor and Pancreatic Cancer: A Rare Case of Solitary Fibrous Tumor and Pancreatic Cancer Concurrence.

Pancreatic ductal adenocarcinoma is the most prevalent form of pancreatic cancer, originating in the duct lining of the pancreas. The simultaneous occurrence with a solitary fibrous tumor (SFT) represents an unexpected finding. We present a case involving a 64-year-old female with synchronous pancreatic cancer and SFT. The patient initially experienced severe abdominal pain, visible jaundice, and itching. Diagnostic imaging revealed a mass in the head of the pancreas and a soft tissue mass in the right hemipelvis. Further investigations included histological examination, immunohistochemistry, and genetic testing. Subsequently, the patient underwent appropriate management, which involved the excision of both masses and radiochemotherapy. The discussion focuses on the genetic linkages in this rare presentation, aiming to identify treatment connections for both tumors. Throughout this case report, our aim is to contribute to enriching the limited literature with new insights and underscore the importance of identifying genetic linkages between both tumors which may lead to more effective management strategies and better treatment outcomes.

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.

Solitary Fibrous Tumor Requiring Abdominal Aortic Vessel Replacement.

Solitary fibrous tumors (SFTs) are mesenchymal tumors, and retroperitoneal occurrence is rare. It has been identified in a variety of soft tissues and organs, such as the pleura, peritoneum, and meninges. In this case, the tumor was in contact with the abdominal aorta, and the invasion was difficult to judge preoperatively. Intraoperatively, it was revealed that the tumor could not be completely removed without aortic replacement. Although SFTs have a generally good prognosis, certain factors, such as tumor incomplete resection, have been reported to increase the risk of recurrence and metastasis. We were able to completely remove the tumor by performing a combined resection of the aorta. The specimens were microscopically disorganized proliferation of spindle-shaped cells. Immunostaining was positive for cluster of differentiation 34 (CD34) and signal transducer and activator of transcription 6 (STAT6). The tumor cells infiltrating into aortic adventitia were observed. This is a valuable case in which artificial blood vessel replacement was able to reduce the risk of recurrence and metastasis due to tumor remnants. We report a rare case of SFT resected with artificial blood vessel replacement.

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.

A phase II, open-label, single-arm trial of pembrolizumab for recurrent meningioma and solitary fibrous tumor.

Background: Atypical and anaplastic meningiomas account for 20% of all meningioma cases. Solitary fibrous tumor (SFT) is a type of soft tissue sarcoma with similar attributes to meningioma. For patients with refractory or recurrent disease after previous surgery or radiotherapy, there is no effective treatment. Pembrolizumab, an anti-programmed cell death 1 (PD-1) antibody, is an effective treatment for various solid tumors. PD-1 ligand is highly expressed in aggressive meningiomas. We aimed to assess the effectiveness of pembrolizumab in treating meningioma and SFT recurrence after surgery and radiation therapy. Methods: This prospective single-arm phase II trial comprised 15 patients with recurrent meningioma and 3 with anaplastic SFT, treated at a single institution during 2018 to 2022. The study was terminated due to a lack of efficacy and slow accrual. The primary endpoint was 6-month progression-free survival (PFS-6). Results: Median progression-free survival (PFS) was 2.6 months, and median overall survival (OS) was 40 months. The 6- and 12-month PFS were both 11.1%. The 6- and 12-month OS were 94.4% and 61.1%, respectively. According to the Response Assessment in Neuro-Oncology (RANO) criteria, the overall response rate was 11%, with 2 patients achieving stable disease and 2 with partial response. Three patients (16.7%) developed grade 3 toxicity. Conclusions: Our results showed that pembrolizumab failed to improve PFS-6 in patients with aggressive meningioma or anaplastic SFT. However, two patients, one with atypical meningioma and one with anaplastic SFT, achieved a partial response. More clinical studies are needed to identify which subset of patients may benefit from this treatment.

Ruptured solitary fibrous tumor of the pleura with hemothorax: a case report.

BACKGROUND: The majority of the patients with a solitary fibrous tumor (SFT) of the pleura are asymptomatic, and rupture of an SFT with hemothorax is rare. CASE PRESENTATION: A 48-year-old man was taken by ambulance to our hospital because of sudden onset of left chest pain. Two months before the referral, a tumor was detected in the left upper lobe of the lung by screening computed tomography at another hospital, and further observation was recommended, because the tumor was suspected to be benign. Our contrast-enhanced computed tomography analysis of the chest revealed a solid tumor (5 cm in diameter) with an irregular enhancement effect close to the pericardium and pleural effusion in the left thoracic cavity. Pleural effusion was not detected in the previous imaging analysis. CT number of the pleural effusion was 40 HU, and the pleural effusion was suspected to be hematogenous. Therefore, rupture of the tumor with bleeding was suspected as the cause of the effusion because of the sudden onset. Preoperative diagnosis was a mediastinal tumor, such as a teratoma, because the tumor was close to the pericardium. Thoracoscopic surgery was performed with the patient in the right lateral decubitus position; bloody pleural effusion was observed and drained. The tumor originated from the visceral pleura of the left upper lobe of the lung and was resected with a surgical stapler. Macroscopic analyses of the resected tumor indicated that bleeding were caused by the rupture of the tumor at the defect of the capsule wall. The operation took 63 min. The postoperative pathological diagnosis was a benign SFT. Hemorrhage was observed just under the capsule wall of the tumor. The postoperative course of the patient was uneventful, and he was discharged 2 days after surgery. CONCLUSIONS: Even when an SFT is neither huge nor malignant, rupture can occur, and resection should be considered regardless of the size or malignant characteristics. After an SFT rupture, careful follow-up is needed to monitor for the intrathoracic recurrence or dissemination of the tumor.

Case report: A rare case of malignant solitary fibrous tumor in an adult with an epithelioid pattern in the occipital region.

We illustrated a rare case of malignant solitary fibrous tumor (MSFT) with epithelioid morphology in the occipital region of a 59-year-old female, in which a rare NAB2ex7-STAT6 exon15/16 double fusion subtype was detected by the Next-generation sequencing (NGS) and STAT6 immunohistochemistry (IHC) was diffusely and strongly positively expressed, without recurrence after 20 months of postoperative follow-up. The morphological and molecular genetic aspects and the differential diagnosis are described, and the relevant literature was assessed in order to broaden our understanding and diagnostic capability of this malignancy.

A case of robotic distal pancreatectomy for solitary fibrous tumor of the pancreas.

Solitary fibrous tumor (SFT) is a spindle cell tumor driven by the NAB2-STAT6 fusion gene. While it can originate from any soft tissue, primary SFT of the pancreas is rare with limited reports. A 36-year-old man came to our department due to abdominal pain. Computed tomography revealed a circular mass with weak peripheral enhancement and an internal cyst in the pancreatic tail. Diagnosis was not confirmed through endoscopic ultrasound-guided biopsy, and differential diagnoses included acinar cell carcinoma and pancreatic neuroendocrine tumor. A robotic distal pancreatectomy with splenectomy was performed, and the patient was discharged 11 days postoperatively. Histopathological examination showed an irregular arrangement of spindle cells, and immunohistochemical staining was positive for CD34 and STAT6, confirming an SFT diagnosis with low metastatic risk. Robotic surgery effectively managed this tumor.

Orbital solitary fibrous tumor.

INTRODUCTION: Solitary fibrous tumor (SFT) is a rare borderline mesenchymal tumor typically arising in the pleura and involving the orbit as its most common extra-pleural location. CASE DESCRIPTION: We herein describe two cases of orbital SFT arising in both a 69-year-old woman presenting with progressive proptosis of the left eye and a 49-year-old woman presenting with binocular diplopia. The diagnoses relied on histopathological analysis of biopsy samples. Because of the poor local prognosis, we decided to perform an orbital exenteration in the first case. In the second case, a complete resection surgery was performed. CONCLUSION: SFT presents classics histological features and immunohistochemical markers that are essential to the diagnosis. SFT is classified as a benign tumor, but in some cases, it can show aggressive behavior with the potential for local tissue invasion and, more scarcely, distant metastasis. This is why complete resection remains the treatment of choice for SFT.

Immunological Tumor Microenvironment of Solitary Fibrous Tumors-Associating Immune Infiltrate with Variables of Prognostic Significance.

BACKGROUND AND OBJECTIVES: Solitary fibrous tumors (SFTs) are morphologically heterogeneous tumors characterized by the NAB2::STAT6 gene fusion. Clinical outcomes may vary widely, and while most cases have favorable outcomes, some can progress to aggressive disease, manifesting as recurrence and metastasis, and ultimately resulting in patient death. Herein, we analyze the immunological tumor microenvironment (ITME) of SFTs, aiming to determine its prognostic value and correlation with established risk stratification systems (RSSs). METHODS: A retrospective observational multicenter study of 52 fusion-confirmed SFTs with clinical follow-up data. Immunohistochemical analysis including CD163, CD68, CD3, CD8, CD20, PDL-1, PD-1, and LAG1 were evaluated in tissue microarrays, using an analog scale with scores ranging from 0 to 3 (0 = ≤9, 1 = 10-49, 2 = 50-99, and 3 = >100 positive cells per 10 high-power fields). The expression of these markers was correlated with clinical outcomes, morphological characteristics previously evaluated in whole slide tissue sections (hypercellularity/hypocellularity, round-oval or spindle dominant constituent cell (DCC) morphology, and necrosis), Ki67, overall survival, and RSS. RESULTS: Only one of the fifty-two cases studied showed progression. In the multivariate analysis, neither the presence nor absence of immune cells (B-lymphocytes, T-lymphocytes, and macrophages) showed any association with the assessed RSSs (Demicco, Sugita, G-score, and Huang). Interestingly, the case that showed progression had high immune infiltrate with expression of CD68, CD163, CD8, and CD20 markers (score of 3). Round-oval cell morphology was associated with the presence of higher levels of CD163 macrophages. Lastly, the scant presence of CD20+ lymphocytes correlated with less necrosis, and cases with higher PDL-1 expression correlated with increased Ki67 values. All cases were negative for LAG-1 and PD-1. CONCLUSIONS: SFT ITME components correlated with independent variables with prognostic significance. Nevertheless, ITME did not correlate with RSS scores.

Renal Solitary Fibrous Tumor With Müllerian Cysts: A Novel Differential Diagnosis for Biphasic Renal Neoplasms.

Solitary fibrous tumor is an uncommon mesenchymal neoplasm, initially described in the pleura and infrequently found in the kidney. It is characterized by haphazardly arranged spindle cells, staghorn vasculature, coexpression of CD34 and signal transducer and activator of transcription 6 (STAT6), and a NAB2::STAT6 gene fusion. We report a 64-year-old woman who presented with a 2.5 cm multilocular cystic renal mass. On microscopic examination, the tumor consisted of a spindle cell component closely intermingled with ciliated and hemorrhagic epithelial cysts. The spindle cell component was positive for CD34, B-cell lymphoma 2 (BCL2), and STAT6, confirming the diagnosis of a solitary fibrous tumor. The epithelial cysts expressed keratin 7, PAX8, BCL2, estrogen receptor 1, and progesterone receptor, indicative of Müllerian cysts. The occurrence of solitary fibrous tumor in the kidney is extremely rare, and its association with Müllerian cysts has not been previously reported in the kidney. This morphologic variant has a striking similarity with biphasic renal neoplasms, especially with mixed epithelial and stromal tumors and angiomyolipoma with epithelial cysts. This report describes a novel renal solitary fibrous tumor subtype within this differential and underscores clinical and pathological distinctions of biphasic renal neoplasms.

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.

Solitary fibrous tumor: A case report of this multifaceted tumor.

BACKGROUND: Solitary fibrous tumor (SFT) is a remarkably uncommon mesenchymal tumor. STAT6 level and a combination of clinical, pathological, and molecular features are required to arrive at a proper diagnosis. CASE SUMMARY: In this report, we present an intriguing case involving a 43-year-old woman who initially exhibited symptoms of a bleeding retroperitoneal tumor, initially resembling a gastrointestinal stromal tumor, but later confirmed as an SFT. However, a year later, what was initially believed to be a recurrence of her SFT was instead identified as a desmoid tumor. CONCLUSION: Distinguishing SFT from other tumors was pivotal. Correcting misdiagnoses of tumor type initially and of recurrence later was necessary for appropriate treatment of the correct desmoid type.