Solitary fibrous tumor of the floor of the mouth: A rare entity in an uncommon site

Pazopanib for recurrent central nervous system solitary fibrous tumors: A single-institution retrospective series.

Refractory paraneoplastic hypoglycemia secondary to a large renal solitary fibrous tumor in a 10-year-old female: a case report

Solitary fibrous tumor (SFT) is an exceedingly rare mesenchymal neoplasm classified as a soft tissue sarcoma (STS). While historically considered indolent, up to 50% of cases can recur or metastasize after long-term follow-up. Complete surgical resection constitutes the cornerstone of treatment for localized disease, while the management of locally advanced or metastatic SFT poses a significant clinical challenge underscoring the need for effective systemic therapies. Antiangiogenic agents have shown promising outcomes, particularly in non-dedifferentiated SFT, and are increasingly favored by some as first-line options. Regarding chemotherapy, traditional anthracycline-based STS regimens have demonstrated limited efficacy, shifting the current focus towards combinations with alkylating agents, such as dacarbazine, and other agents such as microtubule inhibitors, like trabectedin. This review summarizes current systemic therapeutic strategies for SFT, highlighting the central role of antiangiogenic therapy as the standard backbone for managing advanced disease. It also discusses current data on chemotherapy, as well as molecularly targeted and immunomodulatory approaches, which are emerging options that require further validation. In addition, we discuss evolving concepts in systemic treatment sequencing, predictive biomarkers, advanced therapeutic combinations under clinical evaluation, and potential future therapeutic agents and targets.

Desmoid tumors (aggressive fibromatosis) are rare, locally invasive fibroblastic neoplasms with no metastatic potential but a propensity for local recurrence. Primary involvement of the liver is exceptionally uncommon and poses significant diagnostic challenges due to overlapping radiologic features with primary hepatic malignancies and other spindle cell neoplasms. Large mesenchymal tumors may rarely be associated with nonislet cell tumor hypoglycemia. A 71-year-old woman presented with a five-year history of progressive abdominal swelling and recurrent hypoglycemic episodes. Examination revealed a large, firm, non-tender abdominal mass measuring 30.0 × 28.0cm. Laboratory investigations, including liver function tests and tumor markers (alpha-fetoprotein, CA 19 - 9, and CA-125), were within normal limits, except for correctable hypokalemia. Cross-sectional imaging demonstrated a large heterogeneous mass arising from segments II and III of the left hepatic lobe with progressive enhancement, favoring a benign or low-grade mesenchymal neoplasm. Differential diagnoses included solitary fibrous tumor, inflammatory myofibroblastic tumor, and desmoid fibromatosis. The patient underwent left lateral hepatectomy. Histopathology revealed a spindle cell proliferation composed of uniform fibroblastic cells arranged in long fascicles within a collagenous stroma, without significant atypia or increased mitotic activity. Immunohistochemistry showed strong nuclear positivity for beta-catenin, while smooth muscle actin (SMA) and CD31 were negative in tumor cells; S100 showed weak positivity. These findings confirmed the diagnosis of desmoid tumor. The postoperative course was uneventful, with resolution of hypoglycemic episodes. Primary hepatic desmoid tumor is an exceptionally rare entity that may clinically and radiologically mimic malignant hepatic neoplasms. Strong nuclear beta-catenin expression is critical for definitive diagnosis. This case underscores the importance of comprehensive histopathological and immunohistochemical evaluation in atypical hepatic masses and highlights the potential association with paraneoplastic hypoglycemia.

Clinicopathological characteristics and prognosis of central nervous system solitary fibrous tumor: An analysis of 271 cases.

A man in his late sixties with hypertension and a heavy smoking history presented with a large left thoracic mass. Biopsy confirmed a solitary fibrous tumour. Before his scheduled surgery, he collapsed; his blood glucose level was 40 mg/dL, consistent with insulin-like growth factor-II (IGF-II)-mediated hypoglycaemia (Doege-Potter syndrome). Continuous glucose monitoring (CGM) was initiated to characterise perioperative glucose trends and support glucose management. As his consciousness and oral intake improved with supportive care and adjunctive corticosteroids, his glucose level stabilised, allowing gradual tapering of intravenous glucose. He subsequently underwent complete tumour resection via a hemi-clamshell incision. Postoperatively, his glucose level normalised immediately, and CGM documented the disappearance of fluctuations by postoperative day 2. Fifteen months after surgery, he remained recurrence-free without further hypoglycaemic episodes. Histology confirmed a solitary fibrous tumour, and Western blot analysis demonstrated high-molecular-weight IGF-II. This case highlights how perioperative CGM can support perioperative glucose management in patients with intrathoracic solitary fibrous tumours complicated by Doege-Potter syndrome.

Fractal analysis and magnetic resonance imaging (MRI) semantic features to identify intracranial solitary fibrous tumours and atypical meningiomas.

Solitary fibrous tumours of the pleura (SFTP) are rare neoplasms for which surgical resection is considered the gold standard treatment. Anecdotally, SFTPs are sometimes conservatively managed, but there are little data on this in published literature. In this study, we aimed to collect data on radiological features in SFTP which might be associated with a benign clinical course to assist in risk stratification, and therefore selection for a more conservative management pathway. A service evaluation of outcomes of radiologically diagnosed SFTP was completed in 12 UK centres, between 2005 and 2015. Cases were included via initial search of local radiology databases using key words ("Pleural fibroma" OR "fibrous tumour of the pleura" OR "SFTP"). Baseline characteristics and outcome data were obtained from medical records. A total of 270 patients were included in the study. Factors associated with the need for surgical intervention included lesion size (>128 mm), lesion position (abutting the mediastinum or diaphragm), associated pleural effusion, radiological evidence of necrosis within the lesion and heterogeneous density. In multivariate analysis, computed tomography-measured attenuation and homogeneous density were independent risk factors for adverse clinical outcomes in patients with resected fibromas. This is the largest study to date on SFTP to include conservatively managed cases who underwent radiological follow-up only. The results suggest several features associated with adverse clinical outcomes, and thereby may identify cases which could be more conservatively (observation only) managed. Further prospective studies are required to assess the identified risk factors as part of a potential radiological scoring system.

Solitary fibrous tumors are mesenchymal neoplasms that make up 2% of soft tissue tumors. Doege-Potter syndrome (DPS) occurs between 5-10% of patients with solitary fibrous tumor of the pleura (SFTP). Little is mentioned about DPS in the relapse setting, where malignant transformation should always be ruled out (until 12% of cases) according to tumor size, histopathologic aspects (including mitotic index) and immunohistochemical markers. This is the first case of Doege-Potter syndrome in the setting of a fibrous tumor relapse of the pleura without malignant transformation described in Colombia.

Diagnosis and treatment of solitary fibrous tumors of the thyroid gland: the importance of an appropriate diagnostic approach.

A 45-year-old woman presented with right diaphragmatic elevation. Imaging revealed a 13-cm hypervascular mass supplied by the inferior phrenic artery. Preoperative embolisation enabled safe resection. Pathology confirmed a solitary fibrous tumour, highlighting a rare diaphragmatic origin and the utility of embolisation.

Solitary fibrous tumour is an uncommon, predominantly benign tumour of mesenchymal origin, developing mainly in the thoracic cavity and on the pleural surface, although it has been reported in a wide variety of extrapleural sites. Its occurrence in the liver is particularly rare. We present the case of a 57-year-old woman in whom a large mass was identified in the left lobe of the liver, demonstrating inhomogeneous contrast enhancement without significant compression of the abdominal vessels. The lesion measured 170 mm in its greatest diameter and severely destroyed the surrounding liver parenchyma. SFT is characterised by haphazardly arranged ovoid and spindle-shaped cells with numerous mildly staghorn-like vessels lined by flattened endothelium. It typically shows NAB2–STAT6 gene rearrangement with CD34 and/or STAT6 positivity on immunohistochemistry. Since imaging methods are not specific regarding the nature of the lesion, pathological and immunohistochemical analyses are essential for establishing an accurate diagnosis and assessing differential diagnostic possibilities.

Our aim was to explore the noninvasive prediction of intracranial solitary fibrous tumors (ISFTs) with World Health Organization (WHO) grade and Ki-67 expression level based on semantic and whole-tumor histogram features from multiparametric Magnetic Resonance Imaging (MRI). We retrospectively evaluated thirty-nine ISFTs with histologically proved WHO grade 1 (n=25), WHO grade 2-3 (n=14), low Ki-67 (n=31), and high Ki-67 (n=8). Clinical data, MR semantic, and whole-tumor histogram features were collected. The values between the two groups were compared with Mann-Whitney U test or Fisher's exact test. Logistic regression analysis, receiver operating characteristic curve, and integrated discrimination improvement (IDI) were applied to identify the diagnostic performance. Hemorrhage and tumor-brain interface showed significant differences between WHO grade 1 and 2-3 groups (all P＜0.05). WHO grade 1 group showed significantly higher CE-T1WI_mean (contrast-enhanced T1-weighted imaging), CE-T1WI_median, and CE-T1WI_P90 values than grade 2-3 group (all P＜0.05). The combined model integrating tumor-brain interface and CE-T1WI_median achieved the highest area under the receiver operating characteristic curves (AUC) of 0.84, which was superior to each single model with improved IDI (IDI=0.15-0.21). Cystic degeneration and midline shift showed significant differences between high and low Ki-67 groups (all P＜0.05). High Ki-67 group was showed lower ADC_mean (apparent diffusion coefficient), ADC_median, ADC_P90, and T2WI_skewness (T2-weighted imaging) values than low Ki-67 group (all P＜0.05). The combined model integrating ADC_median and T2WI_skewness achieved the highest AUC of 0.94 and outperformed each single model with improved IDI (IDI=0.34-0.43). The combination of MR semantic and whole-tumor histogram features can predict ISFT grades and Ki-67 expression with favorable predictive performance.

Synovial sarcoma is an aggressive and rare malignant soft tissue neoplasm, typically affecting young adults and predominantly arising near major joints. Primary cranial involvement is extremely uncommon. In rare circumstances, patients may develop multiple soft tissue tumors either synchronously or metachronously, raising a challenging differential diagnosis between metastatic disease and a second primary malignancy. We report the case of a woman diagnosed with a primary high-grade cranial synovial sarcoma, treated with wide surgical resection followed by adjuvant radiotherapy, who remained disease-free for two years. She later presented with multifocal skeletal lesions. Biopsies taken from two distinct bone lesions demonstrated diffuse STAT6 positivity and the absence of SS18 rearrangement by molecular analysis. These features, confirmed by independent pathological reviews and a multidisciplinary tumor board, were consistent with a multifocal solitary fibrous tumor rather than metastatic disease. This rare case highlights the diagnostic complexity of multifocal skeletal lesions developing after primary cranial synovial sarcoma and emphasizes the importance of thorough pathological, molecular, and multidisciplinary evaluation.

Objective: To explore the clinicopathological features, immunophenotype, molecular characteristics, and prognosis of primary malignant solitary fibrous tumor (MSFT) of the kidney. Methods: The clinicopathological data of four renal MSFT cases diagnosed at the Ruijin Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China and one case at the Ningbo Clinical Pathology Diagnostic Center, Ningbo, China between 2015 and 2025 were collected. The clinical features, histomorphology, and immunohistochemical characteristics were analyzed. Fluorescence in situ hybridization (FISH) and RNA-based next-generation sequencing were performed. Follow-up and review of relevant literature were conducted. Results: Among the five patients, three were male and two were female, aged 70(61,71) years. The tumors were all found during routine physical examinations. Four cases (cases 1, 3, 4, and 5) occurred in the left kidney, and one case (case 2) first occurred in the left kidney and recurred in the right kidney 5 years later. Four cases had a single lesion with a maximum diameter of 6.0-19.0 cm, and one case (case 5) had 2 lesions with maximum diameters of 2.0 cm and 4.0 cm, respectively. Histologically, three cases (cases 1, 2, and 5) were de novo MSFT, one case (case 5) was morphologically similar to synovial sarcoma with spindle cells arranged densely in bundles, one case (case 1) had sheets of epithelioid tumor cells, and one case (case 2) had alternating myxoid and spindle cell areas, with sparse tumor cells in the myxoid areas and dense tumor cells in the spindle cell areas. Two cases (cases 3 and 4) were classic solitary fibrous tumor (SFT) with dedifferentiation, and the dedifferentiated components were high-grade undifferentiated sarcoma. In the typical SFT areas, tumor cells were alternately dense and sparse, with collagenized areas and rare mitotic figures, while branching or hemangiopericytoma-like structures were also present. In the dedifferentiated areas, tumor cells were spindle-shaped or epithelioid with conspicuous nucleoli. Necrosis was seen in all three de novo MSFT cases (cases 1, 2, and 5) and one dedifferentiated case (case 4). The mitotic figures in three de novo SFT cases and two dedifferentiated areas were 4 to 10 per 10 HPF. No heterologous differentiation was found in any of the five cases. According to the Demicco risk classification, four cases were of moderate risk, and one case (case 4) was of high risk. Four cases showed diffuse expression of STAT6, while one case (case 3) showed partial expression. CD34 was diffusely positive in 3 cases, partially positive in one case (case 4) and negative in one case (case 1). Only one of the 5 cases expressed CKpan which was focally positive. PAX8, desmin, BCOR, S-100 protein, Melan A and HMB45 were all negative. H3k27Me3 expression was retained. FISH showed no SYT (SS18, 18q11) rearrangements in two cases (cases 4 and 5), and no MDM2 amplification in one case (case 5). RNA sequencing in four cases detected NAB2::STAT6 gene fusion, all of which were NAB2ex6::STAT6ex16 fusion subtypes. Follow-up data were available for four cases, with the follow-up period of 11-30 months. Among the 4 cases, one case had liver metastasis 3 months after surgery, and one case of left renal MSFT (moderate risk) had right renal recurrence 5 years after surgery. The other two had no recurrence or metastasis. Conclusions: Renal MSFT with moderate to high-risk is rare, shows a wide morphological spectrum and needs to be differentiated from various tumors. Extensive sampling, careful morphological observation, immunohistochemical staining and molecular detection of NAB2::STAT6 fusion are helpful for the diagnosis. It appears to have aggressive biological behaviors.

Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms most commonly found in the pleura, but may also arise in other anatomical locations. Breast SFTs are extremely rare and infrequently reported. Descriptive data on the clinical, radiological, and pathological characteristics of breast SFTs are important for improving understanding of the disease, treatment strategies, and follow-up planning. The pathology databases of major surgical centers in Hong Kong, covering January 2020 to June 2023, were assessed to identify cases with a diagnostic code for SFT. A systematic literature search was conducted to identify all reported cases of breast SFTs. The search was performed using multiple scientific databases, including PubMed, Web of Science, Embase, and Scopus. We report two cases of breast SFTs in Chinese female patients without a family history of breast cancer. Both patients presented with a palpable breast lump that appeared suspicious on ultrasonography (BI-RADS 4). Both patients underwent surgical excision of the lesions with negative margins. The diagnosis of SFT was established based on immunohistochemical findings in tumor samples obtained from surgical excision. No signs of recurrence were observed at follow-up. A literature review yielded 62 cases of breast SFT, including the two cases reported here. No clinically distinguishing features have been reported in the literature, other than that the majority of patients presented with a mass. SFTs were more commonly found in females (n = 47) than in males (n = 15), although the female-to-male ratio was lower than that observed in other breast cancers. We describe two patients with breast SFTs, together with a comprehensive literature review, to contribute to the currently limited knowledge of this disease. A complete picture of the clinical, radiological, and pathological features of breast SFTs could help improve understanding of the condition and guide appropriate management.

Background: Solitary fibrous tumors are uncommon fibroblastic neoplasms. These tumors are characterized by the recurrent NAB2-STAT6 gene fusion, which is a hallmark of solitary fibrous tumors (SFTs), particularly those arising in the thoracic cavity. While SFTs are mostly found in the abdomen and pleura, they can occur in various locations, including the head and neck region (6% of cases of SFTs). Solitary fibrous tumors of the thyroid (SFTTs) are extremely rare, accounting for only 0.1% of all thyroid tumors. The gold standard imaging modality for thyroid tumors is ultrasonography, even though distinctive characteristics for these types of neoplasms are absent, making pre-operative diagnosis more challenging. Aim: The aim of this study is to perform a systematic literature review and to describe our case by analyzing the main clinical features, histological diagnostic features and treatments of this rare tumor, in order to clarify the behavior and molecular characteristics of SFTTs. Methods: A comprehensive systematic literature review was conducted according to the PRISMA guidelines for SFTTs. We searched the PubMed and EMBASE databases for articles published up to November 2025. The inclusion criteria include confirmed diagnosis of SFTT, while articles describing unrelated neoplasms or articles that were not in English were excluded. A standardized form was used to extract information on the imaging characteristics, histological diagnosis, treatment and outcome. Results: As of 2025, a total of 43 articles were selected, with 61 reported cases of SFTT in the English literature. Pre-operative diagnosis of SFTT is controversial and usually requires immunohistochemical confirmation. In our case, molecular analysis identified, for the first time, a NAB2ex6-STAT6ex17 fusion, contributing to the molecular characterization of this rare tumor. Conclusions: SFTTs are rare and difficult to diagnose; thus, they require a multidisciplinary approach for accurate diagnosis and management. The combination of imaging, cytology, histopathology, and molecular testing is essential in distinguishing SFTTs from other thyroid malignancies. Surgical excision remains the mainstay of treatment, and long-term follow-up is recommended due to the potential risk of recurrence or metastasis.

The occurrence of giant malignant solitary fibrous tumor of the pleura with severe hypoglycemia as the initial symptom is exceedingly rare. This type of tumor requires extensive surgical resection, and the postoperative mortality rate is high. This article documents the nursing experience in such a case. A 68-year-old man was admitted to the hospital because of recurrent episodes of severe hypoglycemia. Examination revealed a giant malignant solitary fibrous tumor measuring 16.5 × 12.6 × 18.1 cm in the thoracic cavity. It was suspected that the patient's hypoglycemia resulted from the tumor's secretion of insulin-like growth factor. Postoperative pathologic examination confirmed the diagnosis of a malignant solitary fibrous tumor originating in the pleura. The patient underwent resection of a right thoracic mass and right pneumonectomy. The interprofessional team-consisting of the thoracic surgeon, an endocrinologist, a respiratory care nurse, a thrombosis specialist nurse, a nutrition nurse, and a critical care nurse-worked together to provide therapy and nursing care. The patient had an uneventful postoperative recovery in the hospital and was discharged on postoperative day 6. He was followed up for 6 months and continued to experience an excellent recovery. Interprofessional collaboration can improve postoperative recovery in cases of giant solitary fibrous tumor of the pleura, preventing potential complications.

Doege-Potter syndrome (DPS) is a paraneoplastic syndrome characterised by episodic hypoglycaemia associated with solitary fibrous tumours (SFTs). It is thought to occur secondary to the secretion of a prohormone of insulin-like growth factor II by the tumour. Here we describe the diagnosis and management of a rare case of seronegative DPS in a patient with a pleural-based SFT.