Pleural Solitary Fibrous Tumor Research Articles

Pleural Solitary Tumors - Long-Term Prognosis Related To Surgery And Clinicopathological Criteria.

Pleural solitary fibrous tumors (SFTs) are indolent mesenchymal neoplasias, generally with good prognosis, for which complete surgical resection is the gold standard. However, local recurrences and distant metastases are reported at variable rates. Risk-assessing criteria and models determining recurrence and metastatic risk have been proposed, and can impact on patient follow-up strategies. We conducted an observational study comprising a 12 years period to characterize a cohort of 20 surgically resected thoracic SFTs, and to retrospectively assess the prognostic value of England's histology criteria and Demicco's 4-tier model. All tumors were pleural-based, 12 patients were women, and the mean age at diagnosis was 62.8 years. The median duration of follow-up was ten years, and at the end of the follow-up, all patients were alive, and no distant metastases were reported. Three cases (15%) had local recurrence at the median time of 89.3 months/7.4 years. The only case with an incomplete surgical resection relapsed. Collectively, tumors with worst prognostic features, specifically a positive margin or tumors with malignant histology or non-low-risk features, according to England's and Demicco's models, respectively, were associated with recurrence. These results confirm the importance of complete surgical resection of SFTs, and show that risk stratification criteria and models can predict important surgical outcomes such as recurrence. Moreover, they support a risk-based follow-up schedule, as patients with higher relapse risk can benefit from close follow-up.

Resection of pleural solitary fibrous tumors with distinct feeding vessels arising from the descending aorta: a case report

BackgroundPleural solitary fibrous tumors (pSFTs) are rare mesenchymal pleural tumors with rich vascularity. Surgical resection is the cornerstone of pSFTs treatment, requiring careful preoperative imaging to delineate lesion extent and vascular supply including contrast-enhanced computed tomography and other examinations depending on its size and characteristics.Case presentationThe patient was a 34-year-old female with a mass measuring approximately 67 × 42 × 65 mm in the left posterior mediastinum. Intraoperatively, the mass demonstrated rich vascularity. Two veins originating from the abdominal cavity entered the lower pole, one converged from the superior pole, draining into the brachiocephalic vein. Additionally, two arteries arose directly from the descending aorta, while several veins drained into the intercostal veins. In response to unexpected intraoperative vascular findings, vascular clips and silk threads were used to ligate them. Subsequently, the tumor was successfully dissected, with approximately 600 ml of blood loss recorded during the 4-hour surgery. The patient exhibited a satisfactory postoperative recovery, and follow-up spanning over six months revealed no indications of recurrence or metastasis.ConclusionsWe firstly present a case of successful resection of a pSFT in a 34-year-old woman with a distinct feeding vessel arising from the descending aorta and describe the related surgical procedures. This case highlights preoperative evaluation of mass vascularity based on contrast-enhanced computed tomography. When blood supply is challenging to clarify, angiography can offer additional details, especially for giant pSFTs. Despite this, thorough intraoperative exploration remains essential to detect unexpected vessels. Appropriate interventions should be customized based on the vascular origins and the surrounding anatomical structures.

Solitary Fibrous Tumor of the Pleura: A Case Report

Solitary fibrous tumors of the pleura are rare malignancies, with fewer than 1000 reported cases. They are either discovered incidentally, or in association of non-specific symptoms such as hypoglycemia. The association of paraneoplastic hypoglycemia and solitary fibrous pleural tumors is rare. Hypoglycemia occurs in large tumors and normalizes after surgery, the treatment of choice for pleural solitary fibrous tumors (PSTF). The authors discuss the management of this rare tumor and the association of solitary fibrous tumor of the pleura (SFTP) with hypoglycemia.

Expression of neuroendocrine markers in meningeal and extrameningeal solitary fibrous tumors: a potential diagnostic pitfall

Solitary fibrous tumors (SFTs) may show unusual morphologies, and in such circumstances, an unexpected immunoprofile can be misleading. Following an index case of myxoid meningeal SFT with a neuroendocrine immunoprofile, we decided to assess a neuroendocrine profile in SFTs from various locations. The cohort of 9 meningeal and 28 extrameningeal SFTs was evaluated for CNS WHO grade (G1-G3) and 4-tiered Demicco risk stratification. Immunohistochemical detection of synaptophysin, chromogranin, INSM1, CD56, and CD57 was performed in each case and semiquantitatively assessed (0: no expression; 1+: <10% positive; 2+: 11-50%; and 3+: >51%); whole sections (meningeal SFTs) or tissue microarray (extrameningeal SFTs) were used for immunohistochemistry. The cohort included 13 men and 24 women. Meningeal SFTs included 5 WHO G1, 3 WHO G2, and 1 WHO G3 tumors. Extrameningeal SFTs included 21 low-risk, 4 intermediate-risk, and 2 high-risk tumors. INSM1 immunoreactivity was observed in 12 of 37 cases (32%; 8 cases 1+, 3 cases 2+, and 1 case 3+); synaptophysin was positive in 6 of 35 cases (19%; 5 cases 1+ and 1 case 2+); CD56 was positive in 20 of 37 cases (54%; 16 cases 1+, 3 cases 2+, and 1 case 3+); and CD57 was expressed in 14 of 36 cases (39%; 5 cases 1+, 4 cases 2+, and 5 cases 3+). Chromogranin positivity was not observed. No significant association was observed between expression of neuroendocrine markers and tumor grade, Demicco risk group or meningeal and extrameningeal location. Extrapleural SFTs showed a tendency for positivity of INSM1 (P=.014, χ2) and CD57 (P=.017, χ2)compared to pleural SFTs.

Pleural solitary fibrous tumour with brain metastasis: an aggressive tumour and pathologic conundrum

Solitary fibrous tumours of the pleura are a rare finding; those with brain metastases are rarer still. Here, we present the evolution of a pleural solitary fibrous tumour in a 70-year-old male treated surgically, and subsequent brain metastasis requiring emergent craniotomy and excision. The patient received adjuvant radiotherapy to the brain and had no recurrence of brain metastases; however, 1 year surveillance imaging demonstrated metastases to the lungs, liver and spleen for which he received chemotherapy but eventually succumbed to the disease process. Solitary fibrous tumours are most often slow-growing, relatively benign neoplasms. However, up to 10% are malignant. This case highlights the importance of surgical resection of these benign tumours with malignant potential.

Late-Onset Non-islet Cell Tumor Hypoglycemia Associated with a Pleural Solitary Fibrous Tumor

Late-Onset Non-islet Cell Tumor Hypoglycemia Associated with a Pleural Solitary Fibrous Tumor

P8‐124: Pierre‐Marie‐Bamberger syndrome in a patient with a malignant pleural solitary fibrous tumor: A rare case with review of literature

P8‐124: Pierre‐Marie‐Bamberger syndrome in a patient with a malignant pleural solitary fibrous tumor: A rare case with review of literature

SOLITARY FIBROUS SARCOMA: LATE PRESENTATION WITH DIRE EFFECTS

TOPIC: Lung Cancer TYPE: Medical Student/Resident Case Reports INTRODUCTION: A 73-year-old woman with history of breast cancer status post radiation and chemotherapy was eval-uated in our emergency department (ED) for left sided chest pain that worsened over the previous month. She had two weeks of progressive physical limitation, and developed orthopnea the night prior which prompted her to seek care. CASE PRESENTATION: In the ED she was noted to have unrelenting left sided pleuritic chest pain. Physical exam was nota-ble for diminished breath sounds on the left side. Computed tomography (CT) scan of her chest re-vealed a 9.7 x 5.5 cm left lung mass with an associated complex loculated effusion. A left sided chest tube was placed for the loculated pleural effusion. It was exudative by Light's criteria, and pleural flu-id hematocrit was consistent with a hemothorax. She underwent a biopsy of the left lung mass which demonstrated CD34, BCL2, STAT6, spindle cell features and staghorn vasculature indicating a ma-lignant solitary fibrous sarcoma (SFS). She eventually underwent resection as an outpatient once staging confirmed no distant metastatic disease. DISCUSSION: The majority of thoracic solitary fibrous tumors (SFTs) are asymptomatic benign intrathoracic masses discovered incidentally on chest imaging. SFS are a malignant subtype of SFT [1]. Our case demon-strates a rare finding of a large left sided malignant solitary fibrous sarcoma that presented with a large hemothorax. SFTs generally arise from CD34+ dendritic mesenchymal cells which are present in nearly all connective tissues [2]. Association with pleural effusion may be associated with an in-creased risk of a malignant tumor [3]. The presence of a hemothorax has also been reported to cor-relate with rapid tumor enlargement [3]. STAT6, CD34, BCL2 are the most commonly found positive markers, with STAT6 sensitivity being reported as high as 100% [4]. CONCLUSIONS: Our patient did have a history of radiation treatment for left sided breast cancer which has been im-plicated in the development of SFS, particularly in the same radiation fields [5, 6]. Prognosis is usual-ly unpredictable with surgery being the gold standard in treatment [7]. In malignant tumors, chemo-therapy and radiation have limited efficacy [7]. Recurrence rates in malignant SFS are high even with complete resection, reported to be around 63% [8]. REFERENCE #1: Davanzo B, Emerson RE, Lisy M, Koniaris LG, Kays JK. Solitary fibrous tumor. Transl Gastroente-rol Hepatol. 2018 Nov 21;3:94. doi: 10.21037/tgh.2018.11.02. PMID: 30603730; PMCID: PMC6286917. REFERENCE #2: Zuo Z, Zhou H, Sun Y, Mao Q, Zhang Y, Gao X. Rapidly growing solitary fibrous tumors of the pleura: a case report and review of the literature. Ann Transl Med. 2020 Jul;8(14):890. doi: 10.21037/atm-20-4974. PMID: 32793734; PMCID: PMC7396790. REFERENCE #3: Tan JH, Hsu AA. Challenges in diagnosis and management of giant solitary fibrous tumour of pleu-ra: a case report. BMC Pulm Med 2016;16:114. 10.1186/s12890-016-0279-0. REFERENCE #4: Zhang P, Xiong K, Lv P, et al. Malignant solitary fibrous tumor occurring in the mediastinal pleura showing NAB2ex4-STAT6ex2 fusion and negative STAT6 immunohistochemistry: A case report. Thorac Cancer 2020;11:1344-9. 10.1111/1759-7714.13395. REFERENCE #5: Rubino C, Shamsaldin A, Lê MG, Labbé M, Guinebretière JM, Chavaudra J, de Vathaire F. Radia-tion dose and risk of soft tissue and bone sarcoma after breast cancer treatment. Breast Cancer Res Treat. 2005;89(3):277–288. doi: 10.1007/s10549-004-2472-8. REFERENCE #6: Karlsson P, Holmberg E, Johansson KA, Kindblom LG, Carstensen J, Wallgren A. Soft tissue sar-coma after treatment for breast cancer. Radiother Oncol. 1996;38(1):25–31. doi: 10.1016/0167-8140(95)01663-5. REFERENCE #7: Ronchi et al., "Extrapleural Solitary Fibrous Tumor: A Distinct Entity from Pleural Solitary Fibrous Tumor. An Update on Clinical, Molecular and Diagnostic Features. REFERENCE #8: Boothe JT, Budd GT, Smolkin MB, et al. Durable Near-Complete Response to Anti-PD-1 Check-point Immunotherapy in a Refractory Malignant Solitary Fibrous Tumor of the Pleura. Case Rep Oncol 2017;10:998-1005. 10.1159/000484041. DISCLOSURES: No relevant relationships by Danish Ahmad, source=Web Response No relevant relationships by Saad Ashraf, source=Web Response No relevant relationships by Fiyad Haniff, source=Web Response no disclosure on file for Jennifer Toth

CD34-negative solitary fibrous tumour of the broad ligament with doege-potter syndrome: a case report

Solitary fibrous tumours (SFT) are rare fibroblastic mesenchymal tumours that can occur in various anatomical sites but are extremely rare in the female genital tract. The broad ligament itself is a rare location for primary tumours and SFT in the broad ligament has only been described twice before in the literature. We report on a case of CD34-negative SFT in a 61-year-old female who presented with Doege-Potter syndrome. This case highlights the unusual presentation and location, atypical CD34 expression and utility of STAT6 immunohistochemistry for SFTs. 1.Chen S, Zheng Y, Chen L, et al. A broad ligament solitary fibrous tumor with Doege-Potter syndrome. Medicine 2018; 97: e12564.2.Zubor P, Kajo K, Szunyogh N, et al. A solitary fibrous tumor in the broad ligament of the uterus. Pathol Res Pract 2007; 203: 555–60.3.Ronchi A, Cozzolino I, Marino FZ, et al. Extrapleural solitary fibrous tumor: A distinct entity from pleural solitary fibrous tumor. An update on clinical, molecular and diagnostic features. Ann Diagn Pathol 2018; 34: 142–50.

Tumor fibroso solitario pleural. Aspectos clínico-patológicos a propósito de un caso

El tumor fibroso pleural es una entidad médica poco frecuente, considerado una tumoración benigna. Representa entre el 5-8 % de los tumores primarios de pleural. Reportamos el caso de un paciente de sexo masculino de 59 años, no fumador con historia de 3 meses de deposiciones líquidas, asociadas a astenia, pérdida de peso y dolor en parrilla costal. Fue ingresado en el servicio de Gastroenterología del Hospital Clínico Quirúrgico Hermanos Ameijeiras, La Habana, Cuba. Se le realizó una radiografía de tórax, observándose como hallazgo accidental una masa tumoral en región para cardiaca, por lo que decide interconsultar con el servicio de Neumología. La tomografía de tórax evidenció una masa tumoral en el tercio inferior del hemitórax izquierdo, el estudio histológico e inmunohistoquímico fue compatible con un tumor fibroso solitario pleural. Conclusiones de este trabajo apuntan a que para el diagnóstico preciso de este tipo de tumor es necesario realizar una tomografía axial de tórax y un análisis histopatológico detallado.

Solitary fibrous tumor of the pleura: A rare mesenchymal tumor presented with hypoglycemia

Solitary fibrous tumor (SFT) is a relatively rare primary tumor of the pleura, originating from the mesenchymal cells. The tumor has a non-specific clinical, laboratory, and radiological features. Patients may be asymptomatic or have non-specific clinical features including chest pain, dyspnea, cough, and paraneoplastic symptoms. Complete surgical resection is indicated in all cases to avoid recurrence of the tumor. We described a 49-yearold woman who presented with unexplained right chest pain and repeated attacks of hypoglycemia, associated with pleural SFT. Keywords: Pleura; thoracic oncology; solitary fibrous tumor; paraneoplastic hypoglycemia; Doege-Potter syndrome

Doege-Potter syndrome: a case report

Doege-Potter syndrome is a rare paraneoplastic syndrome presenting as hypoinsulinemic hypoglycemia due to ectopic secretion of prohormone: insulin-like growth factor-2 (IGF-2) from a solitary fibrous tumor (SFT). It is essentially a non-islet cell tumor hypoglycemia (NICTH) or in more recent terms, an ‘IGF-2oma’. In case of delay in diagnosis, tumor-induced hypoglycemia could cause hypoxic cerebral injury or death. We hereby present a case of 45 years old male who presented with hypoglycemia due to pleural SFT, which is a very rare and unique presentation. Upon biochemical and radiological investigations, Doege-Potter syndrome was diagnosed and the patient was planned for surgical resection of the tumor. This case stresses upon thorough evaluation of patients presenting with non-diabetic hypoglycemia to rule out underlying malignancy.

68Ga-DOTATOC PET/CT in Pleural Solitary Fibrous Tumors.

Solitary fibrous tumor of the pleura (SFTP) is a rare mesenchymal neoplasm. Preoperative diagnosis is usually difficult and based on radiological findings only. We report the imaging results observed in 5 patients with SFTP (2 malignant) obtained by 68Ga-DOTATOC PET/CT. At qualitative analysis, all tumors showed uptake of 68Ga-DOTATOC. Mean tumor SUVmax was 9.9 ± 5.7. The expression of SST2 (somatostatin receptors subtype 2) was confirmed by immunohistochemistry in 2 tumor samples, and by gene amplification of SST2 mRNA in all cases. These data suggest a diagnostic role of radioreceptor PET/CT in SFTP, and open novel potential treatment options in unresectable/metastatic disease.

Solitary fibrous tumor of the pleura with Doege-Potter syndrome.

Solitary fibrous tumor of pleura (SFTP) is a rare tumor. Complete tumor resection is the curative treatment and the key to preventing recurrence.&#x0D; We present here the case of a 65-year-old female diagnosed with a Doege-Potter syndrome who underwent resection of pleural solitary fibrous tumor.

Pleural Solitary Fibrous Tumors-A Retrospective Study on 45 Patients.

Introduction: The purpose of this paper is to study the type, the clinical presentation, and the best diagnostic methods for pleural solitary fibrous tumors (PSFTs), as well as to evaluate which is the most appropriate treatment, especially as PSFTs represent a rare occurrence in the thoracic pathology. Material and Method: A retrospective study was conducted on a group of 45 patients submitted to surgery between January 2015 and December 2019. In most cases, the diagnosis was established through imaging studies—thoracic computed tomography (CT) scan with or without contrast—but also using magnetic resonance imaging (MRI) or positron emission tomography (PET) scans when data from CT scans were scarce. All patients were submitted to surgery with curative intent. Results: Most patients included in this study were asymptomatic, with this pathology being more common in patients over 60 years of age, and more common in women. The occurrence of malignant PSFT in our study was 17.77% (8 cases). All cases were submitted to surgery with curative intent, with a single case developing further recurrence. In order to achieve complete resection en bloc resection of the tumor with the chest wall, resection was performed in two cases, while lower lobectomy, pneumectomy, and hemidiaphragm resection, respectively, were needed in each case. Postoperative mortality was null. Conclusion: Thoracic CT scan remains the most important imagistic investigation in diagnosing. MRI is superior to thoracic CT, especially in cases that involved the larger blood vessels within the thorax, spinal column, or diaphragm. Complete surgical resection is the gold standard in treatment of PSFT, and the prognosis in benign cases is very good.

Comparison of published risk models for prediction of outcome in patients with extrameningeal solitary fibrous tumour.

Solitary fibrous tumours (SFTs) are fibroblastic mesenchymal tumours with a 10-30% metastatic rate. Several risk models have been proposed for extrameningeal SFT, but they have not been evaluated in direct comparison with each other. The aim of this study is to compare the utility of published risk models in a multi-institutional SFT cohort. Clinicopathological data were evaluated for a cohort of extrameningeal SFTs, and used to stratify tumours by the use of five proposed risk models designed for soft tissue and/or pleural SFT [modified Demicco, Pasquali, Salas overall survival (OS), Salas metastasis, and Salas local recurrence (LR)]. Kaplan-Meier and Cox proportional hazards models were used to assess OS, time to first metastasis, time to first LR, and recurrence-free survival (RFS). The study included 303 patients (109 from a referral cancer treatment centre; previously described in the original Demicco model) and an independent cohort from two large hospitals (n=194). The median patient age was 54years, and the median clinical follow-up (available for 220 patients) was 37months. The independent cohort had a 13% risk of metastasis at 5years and a 16% risk of metastasis at 10years. In this cohort, the modified Demicco, Salas OS, and Salas metastasis models predicted metastasis and RFS, whereas the Pasquali model had the best correlation with OS. Multivariate risk models that include mitotic rate and patient age can more accurately predict aggressive behaviour in SFTs, with the modified Demicco and Salas OS risk models showing the best correlation with metastasis and RFS.

Intraoperative glycemic control using an artificial endocrine pancreas in a patient with a recurrent pleural solitary fibrous tumor producing insulin-like growth factor 2: a case report

BackgroundNon-islet cell tumor producing insulin-like growth factor 2 involves hypoglycemia. During tumor resection, intense fluctuation of blood glucose level may occur. An artificial endocrine pancreas has been reported as beneficial for patients with insulinoma as it maintains stable glycemic levels, although scarcely described with insulin-like growth factor 2-releasing tumor.Case presentationAn 84-year-old man had a recurrent left pleural solitary fibrous tumor releasing high molecular weight insulin-like growth factor 2 and experienced a frequent syncope accompanied by hypoglycemia. After anesthesia induction, an artificial endocrine pancreas, STG-55, was connected to the patient. Blood glucose level was stable at around 150 mg/dl during the resection surgery. The patient followed an uneventful course and was discharged without any complications.ConclusionsAn artificial endocrine pancreas may have the potential to stabilize the intraoperative blood glucose change in insulin-like growth factor 2-releasing tumor resection.

Extrapleural solitary fibrous tumor: A distinct entity from pleural solitary fibrous tumor. An update on clinical, molecular and diagnostic features.

Solitary fibrous tumor (SFT) is a mesenchymal neoplasm that was originally described to be localized in the pleura, but thereafter, this has been reported in several anatomic sites. Although the etiology of the neoplasm remains largely unknown, the pathogenesis seems to be related to an NAB2-STAT6 fusion gene due to paracentric inversion on chromosome 12q13. The diagnosis of extrapleural SFT is challenging, owing to its rarity, and requires an integrated approach that includes specific clinical, histological, immunohistochemical, and even molecular findings. Histologically, extrapleural SFT shares morphological features same as those of the pleural SFT because it is characterized by a patternless distribution of both oval- and spindle-shaped cells in a variable collagen stroma. In addition, morphological variants of mixoid, fat-forming, and giant cell-rich tumors are described. A correct diagnosis is mandatory for a proper therapy and management of the patients with extrapleural SFT, as extrapleural SFT is usually more aggressive than pleural form, particularly cases occurring in the mediastinum, retroperitoneum, pelvis, and meninges. Although SFT is usually considered as a clinically indolent neoplasm, the prognosis is substantially unpredictable and only partially related to morphological features. In this context, cellularity, neoplastic borders, cellular atypias, and mitotic activity can show a wide range of variability. We review extrapleural SFT by discussing diagnostic clues, differential diagnosis, recent molecular findings, and prognostic factors.

Non-islet-cell tumour hypoglycaemia (NICTH): About a series of 6 cases

The purpose of this study was to analyse the characteristics of 6 patients managed in a university hospital between 1996 and 2016 for non-islet cell tumor hypoglycemia (NICTH), a form of hypoglycaemia due to the paraneoplastic secretion of IGF-2 or its related substances. ResultsThree of these 6 patients (50%), aged over 69 years, including 2 with acromegaloid phenotype, presented with a pleural solitary fibrous tumor (SFT), with median diameter 20 cm (interquartile range, 12.5–20.5) with a low median SUV (3.3 g/mL (QR, 2–7.5)) on 18F-FDG PET. The other 3 patients presented respectively neuroendocrine carcinoma (NEC) of the palate (70-year-old woman), retroperitoneal myxofibrosarcoma (66-year-old man) and meningeal hemangiopericytoma (36-year-old woman). All 3 were inoperable and did not respond to any therapy other than glucose solution. Corticosteroid therapy was effective in the 3 SFTs and the NEC. One of the SFTs recurred 10 years later with asymptomatic hypoglycemia, which resolved after reintervention. Median (IQR) blood glucose levels of the 6 patients was 0.4g/L (QR, 0.31–0.41), with hypoinsulinemia at 0.7mIU/L (QR 0.7–2.0), undetectable GH, low IGF-1, normal IGF-2 level in 5/6 cases, a high IGF-2:IGF-1 ratio at 26.9 (QR, 20.8–37.8), hypokalemia and hypomagnesemia. ConclusionNICTH is a rare syndrome, which should be considered in the presence of hypoinsulinemic hypoglycemia with low GH and IGF-1, and a IGF-2:IGF-1 ratio>10. Corticosteroid therapy was effective in elderly subjects, particularly with solitary fibrous tumor, which was generally operable. Hemangiopericytoma and myxofibrosarcoma had poor prognosis in younger patients.

Comparison and evaluation of risk factors for meningeal, pleural, and extrapleural solitary fibrous tumors: A clinicopathological study of 92 cases confirmed by STAT6 immunohistochemical staining

Solitary fibrous tumors (SFTs) are an uncommon type of mesenchymal tumors that are presumably fibroblastic in nature. SFTs are translocation-associated neoplasms that can be consistently diagnosed through the evaluation of NAB2/STAT6 gene fusion. Currently, SFTs have a different grading system and criteria according to their primary sites, and the differences and similarities in SFTs according to their primary sites are still poorly understood. Therefore, we compared SFTs according to their primary sites and histologic appearance, and validated the current grading system of SFTs.A total of 92 patients (with 15 meningeal, 40 pleural, and 37 extrapleural SFTs) were evaluated. The patients with pleural SFTs (mean age: 60.2 years) showed a significantly increased age at diagnosis. Tumors with hemangiopericytoma-predominant morphology had significantly higher grades in the evaluation of several risk factors such as cellularity (P<0.001), pleomorphism (P=0.001), and mitotic activity (P<0.001). Consequently, hemangiopericytoma (HPC)-predominant tumors had a significantly higher recurrence rate. The meningeal SFT group had significantly higher proportion of the HPC-predominant histologic phenotype compared with pleural or extrapleural SFTs (66.67% vs. 5.00% or 18.92%, respectively; P<0.001). Consequently, meningeal SFTs showed significantly higher recurrence rates compared with pleural or extrapleural SFTs (33.33% vs. 12.50% or 2.70%, respectively; P=0.009). Regarding the evaluation of risk factors, a tumor size ≥10cm (P=0.017), a mitotic index ≥4/10 high power fields (HPFs) (P=0.001), high tumor cellularity (P=0.003), high nuclear pleomorphism (P=0.005), and tumor necrosis (P=0.004) were associated with both recurrence and disease-specific mortality. Upon evaluation of the usefulness of the criteria using previously described factors, the predictive model was on the borderline of validation. Of the five factors indicated in the log rank test, only a mitotic index ≥4/10 HPFs remained a significant factor in the multivariate Cox model.