Solitary fibrous tumor (SFT) of the pelvis. Clin Imaging. 2008;32:152-156. [PMID: 18313582 DOI: 10.1016/j.clinimag.2007.07.003]

Case report: A rare case of malignant solitary fibrous tumor within the joint cavity with review of the literature

Solitary fibrous tumors (SFTs) are classified as fibroblastic/myofibroblastic tumors that originate from CD34-positive dendritic cells and usually occur in the pleura. In this paper, we describe a case of SFT within the joint cavity of the left knee. A 60-year-old man was admitted to hospital due to swelling in the left knee for the past 8 months without relevant trauma history. X-ray, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET-CT) presented a large, ill-circumscribed, hypervascular, and highly enhanced mass with eccentric calcification and peripheral, intra-lesional vessels. Subsequently, the patient underwent surgical resection. Postoperative pathology confirmed the neoplastic cells to be positive for CD34, Bcl-2, and SATA6, therefore was finally diagnosed as malignant SFT. The patient developed bone metastases within 1 year after surgery. SFT in the joint cavity is rare, and it is difficult to make a preoperative diagnosis.

Unsuccessful laparoscopic resection of a large pelvic solitary fibrous tumor: A case report

We present a rare case of a female pelvic solitary fibrous tumor unsuccessfully resected using single-port laparoscopy, requiring conversion to laparotomy. Although the resection was successful, the surgical approach could have been improved. For large tumors, minimally invasive results are possible with flexible choices of equipment and incision position.

A Rare Solitary Fibrous Tumor of the Mesorectum: A Case Report

Solitary fibrous tumors (SFTs) are rare tumors that predominantly occur in the mesorectum. Few case reports have been published on mesorectal tumors, and this is the seventh case report. A 49-year-old female patient presented with a hypervascularized mesorectal tumor discovered incidentally during a routine medical examination. Using preoperative three-dimensional computed tomography (3D-CT), we identified vessels originating from the superior rectal and lateral sacral arteries, which are important sources of nutrients, and performed the procedure safely and without bleeding. Considering the lack of preoperative diagnosis and rectal blood flow, high anterior resection was performed. The histopathological diagnosis confirmed SFT, and the patient is currently doing well with no recurrence. Although SFT of the mesorectum occurs infrequently, it should be included in the differential diagnosis. In addition, the usefulness of preoperative 3D-CT, including the arterial phase, has been emphasized in such cases. This is the seventh reported case of a rare SFT in the mesorectum. Currently, there is no literature highlighting the usefulness of 3D-CT for SFTs of the mesorectum. However, it is a valuable preparatory tool for preoperative evaluation.

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.

Tumor Fibroso Solitário Primário em Região Pélvica: Relato de Caso

Introdução: O tumor fibroso solitário é uma neoplasia mesenquimal rara, originada de células intersticiais dendríticas CD34 positivas e composta pela justaposição de células fusiformes. Os casos iniciais foram primariamente descritos na região torácica, e o principal sítio, a pleura visceral. Raramente são descritos casos de tumor fibroso solitário extrapleural em região pélvica, demonstrando a possibilidade de múltiplas sítios primários. Relato do caso: Paciente de 38 anos, sexo feminino, previamente saudável e assintomática, procurou orientação médica após uma ultrassonografia pélvica de rotina evidenciar uma imagem heterogênea na região anexial direita, paraovariana, sendo submetida à ressecção cirúrgica da lesão, com diagnóstico de tumor fibroso solitário confirmado por imuno-histoquímica. Discutem-se os aspectos do diagnóstico imuno-histoquímico e do tratamento cirúrgico. Conclusão: Os casos de tumor fibroso solitário em região pélvica podem ser descobertos por meio de ultrassonografia pélvica de rotina. O tratamento cirúrgico, com ressecção ampliada e margens negativas, deve ser o principal objetivo nos casos de tumor fibroso solitário em região pélvica. A obtenção de amostras para análise imuno-histoquímica é recomendada, e a positividade para CD34 e STAT6 aponta o diagnóstico. Recidivas podem ocorrer em até uma década de seguimento, sendo recomendado período longo de acompanhamento pós-cirúrgico.

Mesentery solitary fibrous tumor with postoperative recurrence and sarcomatosis: A case report and review of literature

BACKGROUND

Solitary fibrous tumors are rare neoplasms of mesenchymal origin. They are often of low malignant potential and rarely metastasize. They frequently arise from the pleura and can occur at any soft tissue site in the body. However, these tumors rarely develop in the mesentery, peritoneal cavity or peritoneum.

CASE SUMMARY

We report on a scarce case of solitary fibrous tumor of the rectal mesentery showing sarcomatosis about 4 years after previous tumor resection. This 69-year-old male had no clinical symptoms but was transferred to our hospital because of a suspected tumor recurrence from follow-up abdominal computed tomography. Tumor markers (CEA, CA 19-9 and CA 125) were within the normal range. Open laparotomy showed sarcomatosis, and pathology confirmed its mesenchymal origin and diagnosis as the solitary fibrous tumor. Our case may be the second recurrent mesentery solitary fibrous tumor reported to date, and the only one with progression to sarcomatosis. There has been no evidence of recurrence in follow-up at the 28^th mo after extensive intra-operative peritoneal lavage and cytoreductive surgery.

CONCLUSION

Although there are few risk factors of cancer recurrence in this patient, careful long-term follow-up after cytoreductive surgery is necessary.

Soft tissue solitary fibrous tumors of the musculoskeletal system: spectrum of MRI appearances and characteristic imaging features

OBJECTIVE

Solitary fibrous tumors (SFTs) uncommonly occur in the musculoskeletal system, with limited available data on their MRI appearance. This study was performed to assess the MRI features of SFTs in the musculoskeletal system (MSK-SFTs).

MATERIALS AND METHODS

Pre-treatment MRI in 39 patients with pathologically proven SFTs in the trunk or extremities was evaluated. Patient demographics, clinical management and follow-up, and lesion histology were reviewed. MRI features including lesion location, size, morphology, signal characteristics, vascularity, and relationship to major neurovascular structures were assessed.

RESULTS

MSK-SFTs most frequently occurred in the lower extremity (23/39 cases, 59%), deep to fascia (29/39, 74%), and intermuscular (22/29, 76%) in location. The majority of deep lesions were located along a major neurovascular bundle (20/29, 69%). Lesions had well-defined margins (39/39, 100%), multilobulated contours (27/39, 69%), and measured mean 6.9 ± 2.8 cm. The majority of lesions had slightly hyperintense T1 signal (34/39, 87%) and heterogenous intermediate-to-high T2/STIR signal (28/38, 74%). A "pseudo-cerebriform" internal architectural pattern on fluid-sensitive sequences, with internal lobulations and low signal bands/septations, was observed in 63% (24/38) of lesions. Lesions commonly demonstrated prominent intra-lesional (30/39, 75%) and peripheral juxta-lesional flow voids. Local invasion of surrounding structures was uncommon (3/39, 8%). Mitotically active lesions (p = 0.02) and lesions with tumor necrosis (p < 0.01) were larger in size. Tumor necrosis was associated with T1 heterogeneity (p = 0.04). Distant metastasis occurred in 10% (4/39) of patients, all in mitotically active lesions pre-operatively considered at least at intermediate risk of metastasis.

CONCLUSION

MSK-SFTs commonly present as well-defined, hypervascular masses deep to fascia along major neurovascular bundles, with heterogeneous slightly hyperintense T1 signal, intermediate-to-high T2/STIR signal, and prominent macroscopic flow voids.

Solitary fibrous tumors: Clinical and imaging features from head to toe

Solitary fibrous tumors (SFTs) are rare fibroblastic mesenchymal tumors that are usually benign with variable malignant potential. They can develop in any organ due to their spindle cell origin. The exact etiology of solitary fibrous tumors is unknown. The majority of SFTs are benign with 10-30% of them exhibiting aggressive and malignant features. The aggressiveness of this type of tumor is not associated with its histological features, which makes surgical resection the treatment of choice. We will review the clinical and radiological features and possible differential diagnoses of SFTs according to their anatomical sites following the World Health Organization 2020 classification.

An abdominal-sacral approach with preoperative embolisation for vulvar solitary fibrous tumour: a case report

Background

Solitary fibrous tumours (SFTs) in the female genital tract are uncommon. Resection of these tumours is controversial because it can cause life-threatening haemorrhage. We report a case of vulvar SFT that was excised in a combined abdominal-sacral approach after preoperative embolisation.

Case presentation

At another hospital, an inoperable intrapelvic tumour was diagnosed in a 34-year-old woman. Computed tomography and magnetic resonance imaging showed that the uterus, urinary bladder and rectum were compressed laterally by a pelvic tumour with a maximum diameter of 11 cm. This mass was hypervascular and had a well-defined border. Transperineal biopsy was performed, and immunostaining revealed that the mass was an SFT. The tumour was supplied by feeding vessels from the right iliac arteries. First, we embolised the feeding vessels. Second, we performed surgical resection in a combined abdominal-sacral approach; no blood transfusion was necessary, and no perioperative complications occurred. The final pathological diagnosis was SFT that was positive for CD34 and signal transducer and activator of transcription 6 according to immunohistochemical staining.

Conclusion

During a year of follow-up, the disease did not recur. Treatment of pelvic SFT should aim at complete resection through various approaches after careful measures are taken to prevent haemorrhage.

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”.

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.

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.

Successful laparoscopic treatment of a giant solitary fibrous tumor of the mesorectum: A case report and literature review

A solitary fibrous tumor is a ubiquitous mesenchymal fibroblastic tumor that was previously considered limited to the pleural cavity. Here, we report a rare case of a large solitary fibrous tumor of the mesorectum, which was successfully resected laparoscopically. A 56-year-old woman was referred to our hospital for a giant pelvic mass. Pelvic MRI showed a well-circumscribed mass, 12 cm in diameter, with heterogeneous signal intensity on T₂ -weighted images. It was diagnosed as a benign mesorectal tumor of unknown origin. We successfully resected the entire tumor laparoscopically. Histological examination revealed it to be an extrapleural solitary fibrous tumor. For large tumors in the pelvis, the laparoscopic approach is preferable in terms of intraoperative hemorrhage, as long as they do not invade surrounding tissues.

Radiological findings in pelvic solitary fibrous tumour

Solitary fibrous tumour (SFT) is an uncommon, usually benign mesenchymal neoplasm. SFT was first described in the pleura, but has subsequently been reported to occur in numerous anatomic locations including the abdomen and pelvis. Abdominopelvic SFTs are typically an indolent process, in spite of reaching a large size by the time of diagnosis. The preferred treatment is complete resection followed by extended follow-up surveillance. The risk of local recurrence and metastasis correlates with tumour size and the histological status of surgical margins. We present the imaging findings of a large pelvic SFT in a 61-year-old female, including ultrasound, CT and MRI.

A case of solitary fibrous tumor in the pelvis presenting massive hemorrhage during surgery

Solitary fibrous tumors (SFTs) are unique soft-tissue tumors of submesothelial origin. These tumors are mainly located in the pleural space but they can be originated within a variety of sites, including the abdomen, the pelvis, the soft tissues and the retroperitoneum. SFTs from all sites are usually benign, and the surgical resection is curative in almost all cases. According to the review of literatures, during the surgical resection, massive hemorrhage could occur due to the hypervascular nature of SFTs. This is a case report on SFT in the pelvis presenting great vessel injury, which resulted in life threatening hemorrhage during the resection of tumor. We wish this paper alerts gynecologists about the risk of massive bleeding during the resection of tumor located at adjacent to great vessels in the pelvis.

Ischemic colitis due to a mesenteric arteriovenous malformation in a patient with a connective tissue disorder

Ischemic colitis is a rare, life-threatening, consequence of mesenteric arteriovenous malformations. Ischemia ensues from a steal phenomenon through shunting, and may be compounded by the resulting portal hypertension. Computed tomographic angiography is the most common first-line test because it is quick, non-invasive, and allows for accurate anatomic characterization. Also, high-resolution three-dimensional images can be created for treatment planning. Magnetic resonance angiography is similarly sensitive for vascular mapping. Conventional angiography remains the gold standard for diagnosis and also allows for therapeutic endovascular embolization. Our patient underwent testing using all three of these modalities. We present the first reported case of this entity in a patient with a vascular connective tissue disorder.

CT features of retroperitoneal solitary fibrous tumor: report of three cases and review of the literature

CT findings in three cases with solitary fibrous tumors (SFTs) confirmed by histopathology and immunohistochemistry were reviewed retrospectively, and compared with pathological results. The three tumors were large, well-defined, and smooth contour masses and SFT consisted of solid components of two different densities. On enhanced CT scans, tumors were strongly enhancing, the multiple vascular shadows were seen within the tumor in the arterial phase. There is progressive enhancement from the arterial to the venous phase, and the tumor capsule can be observed. Histologically, the tumors are composed of spindle cells within a background of collagen stroma, and showed a wide range of growth patterns, alternating hypercellular (tumor cell-rich) and hypocellular (collagen-rich) areas. The diagnosis is confirmed by characteristic positive immunohistochemical staining for CD34.

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.

A case of the large retroperitoneal solitary fibrous tumor

A rare autopsy case of the extremely large retroperitoneal solitary fibrous tumor is reported. A 52-year-old female with a huge abdominal distention was found dead at home. She showed remarkable emaciation. The autopsy revealed a huge retroperitoneal tumor weighing 11.9kg (36×30×20cm in size), which occupied the entire intraperitoneal cavity. Histologically, the tumor consisted of spindle parenchymal cells with fibrous tissues. Immunohistochemically, CD34 was positively stained, whereas S-100, smooth muscle actin, and factor VIII were negative. Her cause of death was diagnosed as emaciation due to the compression of the entire intestine by the tumor. This is a rare case of the extremely large retroperitoneal solitary fibrous tumor, which caused the occasional intestinal obstruction. This disease should be considered in the differential diagnosis of retroperitoneal large tumors that cause accidental deaths in forensic autopsies.

Pelvic solitary fibrous tumor originally diagnosed as prostatic in origin

A 71-year-old man was referred to our hospital because of intermittent urine stream and postmicturition dribbling. Magnetic resonance imaging (MRI) results suggested the mass to be a malignant mesenchymal tumor arising from the left lobe of the prostate, on the basis of the presence of a beak sign. Radical prostatectomy and partial rectal excision with subsequent colostomy were performed. Contrary to preoperative MRI, no prostate involvement was found on histologic examination. Histopathologic and immunohistochemical findings showed typical characteristics of solitary fibrous tumors. The patient's postoperative course was uneventful. He showed no signs of recurrence and metastasis at 2-year follow-up.

Solitary fibrous tumor: an update on the spectrum of extrapleural manifestations

Solitary fibrous tumor (SFT) is a rare tumor initially believed to be a benign localized pleural tumor of mesothelial origin. Over the past few years, the literature on this tumor has grown tremendously. The tumor is now reported in diverse bodily locations, and recognized to have a wider range of clinical and radiological features. The most common extrapleural sites of the tumor are the orbits and the extremities. Tumors are often well-circumscribed masses, and vary in size from 1 cm to over 30 cm. The admixture of histological components in the tumor, namely, fibrous tissue, cellular components, and highly vascularized areas consisting of numerous closely packed small to medium-sized blood vessels, influence the imaging appearances of the tumor. On magnetic resonance imaging (MRI), the diagnosis of solitary fibrous tumor is suggested by a well-circumscribed mass that has smooth margins, and focal or diffuse hypointense signal on T2-weighted imaging due to fibrous content in the tumor. SFTs demonstrate strong focal or diffuse contrast enhancement due to the highly vascularized areas in the tumor.

Trans-sacral resection of a solitary fibrous tumor in the pelvis: report of a case

Solitary fibrous tumors (SFTs) develop most commonly in the pleura, although they have occasionally been reported to arise in the pelvic cavity. We report a case of an SFT presenting as a painless nodule in the pelvis of a 56-year-old woman. Histologically, the tumor was composed of spindle-shaped cells arranged without pattern, with short and narrow fascicles and interspersed bundles of thick collagen, and numerous blood vessels with a focally hemangiopericytoma-like appearance. Immunohistochemically, the tumor cells strongly expressed vimentin, CD34, and bcl-2. The tumor was excised via a trans-sacral approach, without preoperative transcatheter embolization, and the patient remains well more than 2 years after her operation. To our knowledge, this is the first case of an SFT in the pelvis, which was excised completely via a trans-sacral approach.

Somatic and visceral solitary fibrous tumors in the abdomen and pelvis: cross-sectional imaging spectrum

Solitary fibrous tumors (SFTs) are a unique group of mesenchymal neoplasms of fibroblastic or myofibroblastic origin. These tumors were originally described as "benign fibrous mesotheliomas" of the pleural cavity and were erroneously thought to be confined to the serosal surfaces (due to a putative mesothelial or submesothelial origin). It is now established that SFTs are ubiquitous neoplasms with both pleural and extrapleural distribution. Extrapleural SFTs commonly occur in middle-aged adults and manifest as asymptomatic, slow-growing, large tumors. Fewer than 5% of patients with SFTs present with symptomatic hypoglycemia. SFTs are histopathologically diverse with a variable admixture of fibroblasts or myofibroblasts, numerous thin-walled vessels, and dense fibrosis. Tumors previously categorized as hemangiopericytomas are now considered cellular variants of SFTs. At imaging, SFTs demonstrate remarkable heterogeneity, with variable degrees of enhancement, necrosis, or hemorrhage. Although most extrapleural SFTs have a benign clinical course, 10%-15% of these tumors demonstrate aggressive behavior in the form of recurrence or malignancy.

Hypervascular subepithelial gastrointestinal masses: CT-pathologic correlation

Although the vast majority of gastrointestinal (GI) masses are epithelial neoplasms, a variety of subepithelial masses are infrequently encountered during endoscopic or radiologic examination. A subepithelial mass, which was previously called a submucosal mass, is defined as a mass covered with normal-appearing mucosa, whether the underlying process is intramural or extramural in origin. At contrast material-enhanced computed tomography (CT), hypervascular subepithelial masses are usually detected more easily than isoattenuating or hypovascular masses. Entities that appear as intramural hypervascular subepithelial lesions include neuroendocrine tumors, GI stromal tumor, glomus tumor, hemangioma, angiosarcoma, Kaposi sarcoma, nerve sheath tumors, hypervascular metastases, heterotopic tissues, and vascular structures. Entities that appear as extramural hypervascular subepithelial lesions include Castleman disease, solitary fibrous tumor, inflammatory myofibroblastic tumor, and actinomycosis. Some rare gastric cancers resemble subepithelial tumors. In comparison with endoscopic ultrasonography, CT is of limited value in differentiating the layers of the GI wall and determining the origin of mass lesions. However, recent advances in multidetector CT with multiplanar reformation allow one to determine whether a GI mass is of epithelial, intramural subepithelial, or extramural subepithelial origin. Furthermore, the full extent of tumors can be delineated, and local invasion and distant metastases can be identified. Familiarity with the characteristic CT appearances of hypervascular subepithelial masses of the GI tract will help radiologists make a more confident diagnosis.

Solitary fibrous tumors of the soft tissues: review of the imaging and clinical features with histopathologic correlation

OBJECTIVE

Solitary fibrous tumors are rare soft-tissue tumors of submesothelial origin with variable malignant potential. Most of these tumors originate within the thoracic cavity, but they can occur in a variety of sites, including the abdomen, pelvis, and soft tissues and muscles. The purpose of this study was to review the imaging findings with clinicopathologic correlation in 34 cases.

CONCLUSION

The finding of a large, solid, vascular tumor, particularly with prominent feeding vessels or a visible fatty component, should alert the radiologist to the possible diagnosis of solitary fibrous tumor. Percutaneous biopsy carries minimal risk and should be used for definitive diagnosis of these lesions, which in many cases are curable with surgery. The prognosis is good for patients with benign tumors but variable for those with malignant tumors.

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

OBJECTIVE

We aimed to analyze the computed tomography (CT) and magnetic resonance imaging (MRI) findings of pelvic solitary fibrous tumors (SFTs) and to improve the diagnostic efficacy for such tumors.

METHODS

Six cases of pelvic SFTs confirmed by histopathology were analyzed retrospectively. Of the 6 patients, 4 had undergone CT scanning, and 2 had undergone magnetic resonance imaging. All the patients had undergone unenhanced and contrast-enhanced examinations, and 2 had also undergone dynamic CT enhancement examination. Image characteristics such as shape, size, number, edge, attenuation or intensity for each lesion before and after contrast enhancement were analyzed and compared with the pathomorphology of the tumors.

RESULTS

All the 6 cases showed oval or rounded and well-defined masses. Unenhanced CT images showed heterogeneous masses with patchy, necrotic foci in 3 cases and homogeneous mass in 1 case. None of the tumors showed calcification. Contrast-enhanced CT images showed marked, heterogeneous enhancement in the first and second cases. Dynamic enhancement scan demonstrated mild homogeneous enhancement in the third case and mild prolonged, delayed enhancement and washout in the fourth case. T1-weighted MR images showed heterogeneous mild hypointense lesion with linear hyperintensity in 1 case, and homogeneous isointensity in the other. T2-weighted images showed heterogeneous mixed intensity in 1 case and mostly hyperintensive lesion with hypointense foci in another case. A case showed marked heterogeneous enhancement and another showed marked homogeneous enhancement on contrast-enhanced T1-weighted images.

CONCLUSION

Radiological findings of pelvic SFTs are variable and nonspecific. However, a well-defined, ovoid or rounded mass with hypointense on MR T2-weighted images and variable enhancement on CT and MR images may suggest the diagnosis of SFTs. Pelvic SFTs should be included in the differential diagnosis of regional tumors.