Computed tomography and magnetic resonance imaging findings of solitary fibrous tumors in the pelvis: correlation with histopathological findings

Diagnostics and Treatment of Extrameningeal Solitary Fibrous Tumors

Solitary fibrous tumors (SFT) are rare mesenchymal neoplasms that account for less than 2% of all soft tissue masses. In the latest WHO 2020 Classification of Soft Tissue Tumors, extrameningeal SFT was listed as intermediate (rarely metastasizing) or malignant neoplasms. Due to the lack of characteristic clinical features, their diagnosis and treatment remain challenging. The pathogenesis of SFT is often associated with the presence of fusions of the NAB2-STAT6 gene on the 12q13 chromosome. Cytoplasmic CD34 positive staining is considerably characteristic for most SFTs; less frequently, factor XII, vimentin, bcl-2, and CD99 are present. A key factor in the diagnosis is the prevalent nuclear location of STAT6 expression. Radical resection is the mainstay of localized SFTs. In the case of unresectable disease, only radiotherapy or radio-chemotherapy may significantly ensure long-term local control of primary and metastatic lesions. To date, no practical guidelines have been published for the treatment of advanced or metastatic disease. Classical anthracycline-based chemotherapy is applicable. The latest studies suggest that antiangiogenic therapies should be considered after first-line treatment. Other drugs, such as imatinib, figitumumab, axitinib, and eribulin, are also being tested. Definitive radiotherapy appears to be a promising therapeutic modality. Since standards for the treatment of advanced and metastatic diseases are not available, further investigation of novel agents is necessary.

A multicentre retrospective study on extra-thoracic solitary fibrous tumour: preoperative MRI findings predict intraoperative findings and postoperative prognosis

OBJECTIVE

The present study investigated the relationships between the preoperative and operative findings of solitary fibrous tumour (SFT) and between preoperative findings and prognosis.

METHODS

We reviewed 50 SFT patients treated at our musculoskeletal oncology hospital group. We analyzed preoperative clinical findings, particularly MRI imaging findings, and intraoperative information as well as the relationship between preoperative findings and outcomes.

RESULTS

Mean age was 48.9 years and the mean follow-up was 51.8 months. Prior to surgery, needle biopsy was performed on 27 patients and open biopsy on 14. T2-weighted images showed a high signal intensity in 24 patients and heterogeneous signal intensity in 20. Tumours had polylobular contours in 17 patients and smooth and round contours in 27. Collateral feeding vessels were detected in 22 patients. Gd-enhanced MRI was performed on 23 patients, and showed 15 with homogeneous enhancement and 8 with heterogeneous enhancement. Surgical times were significantly longer in patients with a retroperitoneal origin, a tumour of 10 cm or more, and polylobular-type tumours. Intraoperative blood loss was significantly greater in patients with a retroperitoneal origin and heterogeneous Gd-MRI-enhanced tumours. In histopathological evaluations, surgical margins were positive in 12 patients. Local recurrence was observed in one patient. Distant metastasis was noted in eight patients, four of whom had pulmonary metastases. Positive surgical margins were more common in polylobular-type tumours. Distant metastases were more likely to appear in patients with observable collateral feeding vessels and heterogeneous Gd-MRI enhancement.

CONCLUSION

The present results suggest that preoperative clinical findings in SFT patients predict longer surgical times and the risk of increased intraoperative blood loss. Moreover, the risk of a positive surgical margin and postoperative distant metastases may be predicted based on preoperative MRI.

[Solitary fibrous tumor of the prostate: case report]

La tumeur fibreuse solitaire est une tumeur mésenchymateuse souvent bénigne et rare décrite pour la première fois dans la plèvre, la localisation prostatique est exceptionnelle. Nous rapportons le cas d´un patient de 77 ans qui a consulté pour symptômes du bas appareil urinaire à type de dysurie et pollakiurie. Le scanner et l´imagerie par résonance magnétique (IRM) ont montré l´origine prostatique de la lésion et précisé les rapports de cette masse avec les structures adjacentes saines, élément important pour la résécabilité de la tumeur. La biopsie transrectale avec une étude immunohistochimie ont confirmés le diagnostic, les cellules tumorales exprimaient le CD34, Bcl2 et CD 99. Le traitement était chirurgical par prostatectomie radicale.

Doege-Potter syndrome: a systematic review of the literature and case presentation of a rare pelvic malignant solitary fibrous tumour

Solitary fibrous tumours (SFTs) are a rare mesenchymal neoplasm with an incidence of 2.8 per 100 000 of which only 1% occur in the female genital tract. Doege-Potter syndrome is a paraneoplastic phenomenon associated with approximately 5%-10% of SFTs and is characterised by non-islet cell hypoglycaemia due to tumour production of low molecular weight insulin-like growth factor-II. We present the fourth confirmed case of female pelvic SFT with Doege-Potter syndrome and a literature review.

Solitary fibrous tumor of the mesentery: a case report and review of the literature

Solitary fibrous tumors are rare mesenchymal tumors that typically arise from the pleura and rarely originate from the mesentery. We herein report a case involving a 66-year-old patient who presented with a mass on the left abdomen. This mass had been incidentally noticed 10 years earlier. The patient sometimes experienced abdominal pain. Physical examination revealed an irregular mass, which was resected. A biopsy of the mass revealed that it was a solitary fibrous tumor originating from the mesentery of the small intestine. The patient was discharged 1 week after surgery and had an uneventful clinical course throughout the 4-month postoperative follow-up.

Solitary fibrous tumor with atypical features of the paravesical space: benign clinical course at the 10-years follow-up. Report of a case and review of the literature

Extra-pleural solitary fibrous tumor (SFT) is a relatively rare soft tissue neoplasm, with only rare cases reported in the pelvic cavity. Most SFTs are histologically benign, with only a few malignant cases reported in the literature so far. We report a rare case of SFT arising in the paravesical space of a 79-year-old man. Histologically the tumor corresponds to an “intermediate risk tumor” according to a risk stratification scheme for metastatic potential, which incorporates patient age, tumor size, mitotic activity and necrosis. Notably tumor showed a benign clinical course without evidence of local recurrence after a 10-years follow-up. Tumor was composed of both spindle and epithelioid cells variably set in a fibro-myxoid stroma, with focal pleomorphic, necrotic and highly mitotic (> 4 mitoses/10HPF) areas. Immunohistochemistry, showing a diffuse CD34 and STAT6 immunoreactivity, supported the diagnosis of SFT. The present case emphasizes that the clinical course of the pelvic SFTs with atypical morphological features is unpredictable on the basis of morphology alone, and thus the term “SFT with atypical features, including the risk stratification class” should be preferred to “malignant SFT”.

Imaging Features of Sclerosing Epithelioid Fibrosarcoma of the Pancreas: A Case Report

Background: Sclerosing epithelioid fibrosarcoma (SEF) is an extremely rare fibrosarcoma variant. There is no complete imaging data on SEF involving the pancreas. Herein we report the computed tomography (CT) and magnetic resonance imaging (MRI) data of a patient with SEF that primarily involved the pancreas.

Case Presentation: A 64-year-old man was found to have a solid mass in the tail of the pancreas on unenhanced CT. He had no constitutional symptoms. Contrast-enhanced abdominal CT and MRI were performed, and the results of the latter provided the diagnosis of a pancreatic neuroendocrine tumor. Laparoscopic distal pancreatectomy and splenectomy were performed. Anatomopathological examination and immunohistochemistry confirmed that the tumor was a SEF of the pancreas. The patient had no signs of recurrence or metastasis during a 12-months follow-up.

Conclusion: We report an extremely rare case of SEF in the pancreas and its characterization with CT and MRI.

A solitary fibrous tumor/hemangiopericytoma of the fourth ventricle: case report and literature review

Solitary fibrous tumors/hemangiopericytomas (SFTs/HPCs) are rare in the central nervous system and intraventricular SFTs/HPCs are even rarer. We present a clinical case of SFT/HPC that was located in the fourth ventricle and performed a literature review of radiological findings of SFT/HPC. The patient was a 52-year-old man who presented to our hospital with dizziness and progressive weakness in his left extremities. Computed tomography and magnetic resonance imaging showed an irregular-shaped mass in the fourth ventricle. The upper anterior and lower posterior parts of the mass showed different densities and signal intensities, which formed a black and white sign. The upper anterior and lower posterior parts of the mass were enhanced to different degrees, and showed heterogeneous reversed enhancement. The patient underwent surgical resection and the mass was histologically confirmed to be an SFT/HPC. SFTs/HPCs of the fourth ventricle are rare, but show characteristic radiological presentations. In the present case, we observed a solid mass with flow voids, black and white sign, and heterogeneously reversed enhancement in the fourth ventricle. Collectively, these radiological features suggested the diagnosis of SFT/HPC.

Localized giant solitary fibrous tumor of the scrotum: a rare case report and literature review

Background

A solitary fibrous tumor (SFT) is a fibroblastic mesenchymal tumor initially thought to originate from the pleura but that may arise at almost any anatomic site. It is mostly benign, and surgical resection is usually the best treatment option. An SFT involving the scrotum is extremely rare. Case presentation: We herein report an uncommon case of a 22-year-old man who presented with a huge asymptomatic scrotal mass that had begun growing 3 years before presentation. Contrast-enhanced computed tomography revealed a heterogeneous, well-circumscribed scrotal mass with soft tissue density. No invasion of the surrounding organs, distal metastasis, or lymph node swelling was present. Complete resection of the mass was successfully performed. The specimen was a 14.5 × 12.0 × 9.5 cm encapsulated tumor that weighed 970 g. After pathological analysis, we confirmed the diagnosis of SFT. This diagnosis was based on clinical findings, histological morphology, and immunohistochemistry. No recurrence or metastasis was observed during a 3-year follow-up.

Conclusion

SFTs have an unpredictable clinical course, and they are difficult to diagnose and easy to misdiagnose. A scrotal location is extremely rare. Complete resection of the mass is the treatment of choice and is associated with a high success rate and low recurrence rate.

Ischiorectal fossa: benign and malignant neoplasms of this "ignored" radiological anatomical space

PURPOSE

To review the pertinent anatomy and the imaging features of common and uncommon benign and malignant neoplasms and masses of the ischiorectal fossa.

RESULTS

The ischiorectal or ischioanal fossa is the largest space in the anorectal region. The benign neoplasms that develop in the ischiorectal originate from the different components that forms the fossa including vascular tumors such as aggressive angiomyxoma or hemangioma; neural tumors as plexiform neurofibroma or schwannoma; fat tumors as lipoma; skin/skin appendages tumors as hidradenoma papilliferum; smooth or skeletal muscle tumors as solitary fibrous tumor. The malignant neoplasms that develop in the ischiorectal fossa also originate from different components that forms the fossa including vascular tumors such as angiosarcoma, neural tumors as malignant granular cell tumor and malignant peripheral nerve sheath tumor; fat tumors as liposarcoma; smooth or skeletal muscle tumors as leiomyosarcoma, rhabdomyosarcoma, malignant PEComa, or undifferentiated pleomorphic sarcoma. Additionally, the ischiorectal fossa can also harbor secondary hematogenous metastases and be affected by direct invasion from neoplasms of adjacent pelvic organs and structures. Furthermore, other miscellaneous masses can occur in the ischiorectal fossa including congenital and developmental lesions, and inflammatory and infectious processes.

CONCLUSION

Knowledge of the anatomy, and the spectrum of imaging findings of common and uncommon benign and malignant neoplasms of the ischiorectal fossa is crucial for the radiologists during interpretation of images allowing them to make contributions to the diagnosis and better patient management.

Solitary fibrous tumor arising from pelvic retroperitoneum: A report of two cases and a review of the literature

Solitary fibrous tumors (SFT) rarely arise in the pelvis. Here, we report two cases of SFT arising from the pelvic retroperitoneum. The first case involves a 64-year-old woman diagnosed with a 5-cm pelvic mass. Magnetic resonance imaging revealed a solid and cystic mass with marked enhancement, but limited water restriction. During surgery, intraligamental tumor arising near the round ligament was resected. Pathologically, the tumor comprised dilated vessels and spindle-shaped cells positive for STAT6 and CD34. The second case involves a 53-year-old woman diagnosed with a 4.5-cm pelvic mass through computed tomography. Magnetic resonance imaging demonstrated a solid mass with multiple cysts with strong enhancement and slight water restriction. During surgery, the tumor was found in the retroperitoneum. Pathologically, spindle-shaped tumor cells positive for STAT6 and CD34 had proliferated around the prominent hyalinized vessels. Although rare in the pelvis, SFT should be suspected when a mass with strong enhancement is found.

A case of malignant solitary fibrous tumor of the prostatic urethra

A 68-year-old male with dementia presented with gross hematuria. On plain CT, a mass was found at the base of the prostate with intravesical protrusion. On MRI, the mass was well-circumscribed and showed slight hyperintensity compared to the skeletal muscle on T₁ weighted imaging and high intensity on T₂ weighted imaging. On dynamic study, the tumor showed mild enhancement in the early phase and increased enhancement in the delayed phase, and the mass appeared continuous with the prostatic urethra. On follow-up MRI at approximately 10 months, the mass had increased in size. Pathologically, the tumor was located in the muscularis of the prostatic urethra and consisted of spindle cells with fascicular and storiform patterns of growth, and exhibited strong diffuse expression of CD34. The tumor was hypercellular, and a significant number of mitoses were observed. Therefore, this tumor was diagnosed as malignant solitary fibrous tumor (SFT) of the prostatic urethra.

Magnetic resonance features of meningeal solitary fibrous tumors

The aim of the present study was to investigate magnetic resonance (MR) features of meningeal solitary fibrous tumors (SFTs) in order to improve their recognition. The study retrospectively analyzed MR manifestations in 12 cases of meningeal SFTs confirmed by surgery. The lesions were analyzed in terms of the site of their growth, growth mode, morphology, size, changes in the MR signal and the edge of the focus. The tumors were malignant in 3 cases, benign in 7 cases and borderline in 2 cases. A total of 3 cases spanned the tentorium cerebelli, 3 spanned the falx and another case was close to the falx. Overall, 4 superficial tumors were accompanied by adjacent bony destruction. One case was located at the triangular area created by the right lateral ventricles. The tumors were all lobular, with a large diameter and more cystic areas in the center of the focus. The signals were often heterogeneous. The parenchyma in the tumors was significantly enhanced. For certain tumors, the signal was usually inhomogeneous and not uniform. The MR features of a SFT were often similar to other intracranial tumors and easily misdiagnosed. There were certain innate characteristics, for example, the tumor was often a solitary large soft-tissue mass with an irregular edge and a clear boundary, with a lobulated contour, and was widely involved with other tissues. The tumors often grew across either the falx or tentorium cerebelli. A significantly inhomogeneous signal was found and either a low or low-high mixed signal on T2-weighted images in particular. These features are useful for the differential diagnosis of SFTs and other tumors.

Solitary Fibrous Tumors: 2016 Imaging Update

Optimal management of solitary fibrous tumor requires a multidisciplinary approach with proper histopathological mapping and use of various imaging modalities for exact delineation of primary tumor and metastatic disease if present. In this article, the authors present a comprehensive review of the spectrum of imaging findings of solitary fibrous tumors involving various organ systems and discuss the role of molecular targeted therapies in the management of metastatic disease.

Variable Solitary Fibrous Tumor Locations: CT and MR Imaging Features

The aim of the study is to describe the radiological imaging features of different solitary fibrous tumors (SFTs) locations and present histopathological correlations. From 2007 to 2013, 20 cases of histologically confirmed that SFTs were retrospectively analyzed with computed tomography (CT; 9/20), magnetic resonance imaging (MRI; 5/20), or both CT and MRI (6/20). All 20 SFTs were well defined, lobular, soft-tissue masses, and 60% were located outside of the pleura. One pleural case invaded to the 10th thoracic vertebra and had lung metastases. Images revealed 11 heterogeneous lesions that exceeded 3.0 ± 0.203 cm along the greatest axis with patchy necrotic foci, and 9 homogeneous lesions <3.0 ± 0.203. Microscopically, all SFTs were proliferative spindle cells with varying degrees of fibrosis and interspersed vessel branching. Cells were strongly immunopositive for CD34. Here we review variable imaging findings of SFTs, which can be within the pleura as well as within other serosal tissues such as the meninges and postperitoneum. SFTs > 3.0 ± 0.203 cm along the greatest axis appeared to be mixed patterns, whereas SFTs < 3.0 ± 0.203 cm had isodense appearances. SFTs cells were CD34 immunopositive and surgery was a first-line treatment choice.

Dermatofibrosarcoma Protuberans: Computed Tomography and Magnetic Resonance Imaging Findings

The aim of this study was to analyze the computed tomography (CT) and magnetic resonance imaging (MRI) findings of dermatofibrosarcoma protuberans (DFSP), with a view to improving the diagnosis of this kind of tumor. A total of 27 cases of histopathologically confirmed DFSP were analyzed retrospectively. Of these, 18 patients underwent a CT scan and 9 patients underwent an MRI. All patients underwent unenhanced and contrast-enhanced examinations; 1 patient underwent multiphrase CT enhancement examination. Imaging characteristics, including location, shape, size, number, edge, and attenuation or intensity of each lesion, both unenhanced and contrast enhanced, were analyzed. Of the 27 cases, 24 were solitary, 2 had 2 nodules, and 1 had multiple confluent tumors. The lesion with multiple confluent tumors was ill defined and irregular; the other lesions were oval or round, well-defined nodules or masses. The unenhanced CT images showed 19 homogenous isodense lesions. There was no calcification in any of the patients. The contrast-enhanced CT images showed intermediate and marked nonhomogeneous enhancement in 13 lesions, intermediate homogeneous enhancement in 4 lesions, and a mild heterogeneous enhancement in 2 lesions. MR T1-weighted images revealed 1 ill-defined and 9 well-defined homogeneous isointense lesions. T2-weighted images showed homogeneous hyperintensity to the muscles in 6 lesions, 3 mild hyperintense lesions with hypointense lesions, and 1 mixed, mild hyperintense and isointense lesion. Contrast-enhanced T1-weighted images demonstrated intermediate and marked nonhomogeneous enhancement in 9 lesions and intermediate homogeneous enhancement in 1 lesion. DFSP is characterized by a subcutaneous well-defined soft tissue nodule or mass on plain CT/MR scans, and shows intermediate-to-marked enhancement on contrast-enhanced CT/MR scans. The imaging findings for DFSP are nonspecific, but may help to define the diagnosis in an appropriate clinical setting.

Solitary fibrous tumor of the spermatic cord: A case report and literature review

A 31-year-old male patient with a six-year history of left inguinoscrotal swelling was admitted to the Second Xiangya Hospital (Changsha, China). The mass was not found to be associated with intraperitoneal pressure. Ultrasonography and computed tomography examinations demonstrated several solid, botryoidal masses involving the spermatic cord, with limited capacity of mobility. The demarcation between the masses and the left testicle was clear; thus, the masses were removed by a left spermatic cord tumor resection via a left inguinal approach, under epidural anesthesia. Positive staining of the tumor markers, CD34⁺, CD99⁺ and Bcl-2⁺, was confirmed by pathological examination following surgery, and a solitary fibrous tumor of the spermatic cord was diagnosed. No recurrence and metastasis were observed in the patient during the subsequent 25-month follow-up period.

Solitary fibrous tumors in abdomen and pelvis: Imaging characteristics and radiologic-pathologic correlation

AIM: To describe the imaging features of solitary fibrous tumors (SFTs) in the abdomen and pelvis, and the clinical and pathologic correlations.

METHODS: Fifteen patients with pathologically confirmed SFTs in the abdomen and pelvis were retrospectively studied with imaging techniques by two radiologists in consensus. Patients underwent unenhanced and contrast-enhanced imaging, as follows: 3 with computed tomography (CT) and magnetic resonance imaging (MRI) examination, 8 with CT examination only, and 4 with MRI examination only. Image characteristics such as size, shape, margin, attenuation or intensity, and pattern of enhancement were analyzed and correlated with the microscopic findings identified from surgical specimens. In addition, patient demographics, presentation, and outcomes were recorded.

RESULTS: Of the 15 patients evaluated, local symptoms related to the mass were found in 11 cases at admission. The size of the mass ranged from 3.4 to 25.1 cm (mean, 11.5 cm). Nine cases were round or oval, 6 were lobulated, and 10 displaced adjacent organs. Unenhanced CT revealed a heterogeneous isodense mass in 7 cases, homogeneous isodense mass in 3 cases, and punctuated calcification in one case. On MRI, most of the lesions (6/7) were heterogeneous isointense and heterogeneous hyperintense on T1-weighted images and T2-weighted images, respectively. All tumors showed moderate to marked enhancement. Heterogeneous enhancement was revealed in 11 lesions, and 7 of these had cysts, necrosis, or hemorrhage. Early nonuniform enhancement with a radial area that proved to be a fibrous component was observed in 4 lesions, which showed progressive enhancement in the venous and delayed phase. No statistical difference in the imaging findings was observed between the histologically benign and malignant lesions. Three patients had local recurrence or metastasis at follow-up.

CONCLUSION: Abdominal and pelvic SFTs commonly appeared as large, solid, well-defined, hypervascular masses with variable degrees of necrosis or cystic change that often displaced adjacent structures.

Solitary fibrous tumors of the soft tissues: imaging features with histopathologic correlations

Purpose

To describe the imaging features of soft tissue solitary fibrous tumors, with histopathological correlations and clinical outcome.

Material and methods

Twenty-seven patients with histologically proven SFTs were retrospectively evaluated. Imaging studies included six radiographs, five U/S studies, eighteen CT scans, fourteen MRI exams, and one angiography.

Results

On CT scans, two lesions were isodense and five were mildly hypodense compared to muscle while 11 lesions appeared heterogeneous-mixed of iso and hypodense areas. Heterogeneous enhancement was depicted in 13 lesions and four lesions enhanced homogeneously. Six lesions were partially calcified. On T1W MR images, seven lesions were isointense and one was slightly hyperintense relative to adjacent muscles while five lesions appeared heterogeneous-mixed of iso and hypointense areas. T2W images showed high SI in two cases and heterogeneous-mixed in seven cases. Enhancement was heterogeneous in six and homogeneous in four lesions. Patchy unenhanced areas (on CT and T1W MR images) along with patchy areas of low to markedly high SI on T2W images were depicted in 19 lesions. The enhanced portions correlated to areas of increased vascularity and cellularity. The four clinically more aggressive lesions could not be predicted on imaging.

Conclusion

Typical soft tissue SFTs are deep masses made of isodense and isointense areas relative to adjacent muscles mixed with hypodense and hypointense areas on unenhanced CT and MR T1W respectively. Variable enhancement patterns and mixed to high signal intensities on MRT2W are attributed to tumor’s cellularity, vascularity, collagen distribution and/or degeneration. Heterogeneity of SFTs affects imaging features on MRI and CT modalities. The biological behavior of soft tissue SFTs can not be predicted based solely either on histopathologic or imaging evaluation.