• STAT-6
• Solitary fibrous tumor
• case report
• immunohistochemistry
• prostate

• Humans
• Male
• Prostate/pathology
• Prostate/surgery
• Prostatic Hyperplasia/diagnosis
• Prostatic Hyperplasia/surgery
• Prostatic Neoplasms/pathology
• Prostatic Neoplasms/surgery
• Solitary Fibrous Tumors/diagnosis
• Solitary Fibrous Tumors/pathology
• Solitary Fibrous Tumors/surgery
• Transurethral Resection of Prostate

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”.

• pelvis
• review
• risk category
• solitary fibrous tumor

• computed tomography
• immunohistochemistry
• magnetic resonance imaging
• pelvis
• solitary fibrous tumor

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.

Solitary fibrous tumors are primary mesenchymal tumors, which may occur in any part of the body. Overall, these tumors are considered to have intermediate malignant potential with 5- and 10-year metastasis-free and overall disease-specific survival rates of 74% and 55%, and 89% and 73%, respectively (Demicco et al, 2012). Herein we present an unusual case of solitary fibrous tumors involving the ischioanal fossa in a 19-year-old woman with radiologic-pathologic correlation. This case was complicated by extensive tumor vascularity and was thus managed with preoperative embolization followed by en bloc surgical resection.

• Embolization
• Hemangiopericytoma
• Ischioanal
• Solitary fibrous tumor

Solitary fibrous tumors are rare neoplasms of mesenchymal origin. They are often of low malignant potential and rarely metastasize. While they frequently arise from the pleura, they can occur at any soft tissue site in the body. We present a case of a large (28 × 21cm) malignant solitary fibrous tumor arising from the bladder serosa. In addition, the clinicopathologic features, differential diagnosis, cytogenetics and management of this rare disease are discussed, along with a review of the existing literature on this topic.

An otherwise healthy 41-year-old Caucasian man presented with weight loss and progressive abdominal bloating. A subsequent computed tomography scan of his chest, abdomen and pelvis revealed a 26.8 × 21cm intra-abdominal mass occupying most of his abdominal cavity. The inferior vena cava was compressed, and the mass extended inferiorly to his upper pelvis abutting the superior dome of his bladder. He underwent operative resection and the resected mass measured 28 × 21 × 18cm and weighed 4.8kg. The cut surface revealed a gray-white mass with an ill-defined whorled-like pattern, with randomly assorted tan fleshy nodules. A histologic evaluation revealed variable, alternating hypercellular and hypocellular areas, with areas of necrosis. The tumor cells varied from spindle to epithelioid within a hyalinized stroma. In the hypercellular areas, the tumor cells showed moderate atypia with high mitotic activity. The histological features combined with immunophenotyping were suggestive of a malignant solitary fibrous tumor that grossly appeared to be growing from the bladder serosa, specifically the intraperitoneal superior dome of the bladder. Our patient is currently eight months post-surgery without evidence of recurrence.

Extrapleural occurrences of solitary fibrosis tumors are being increasingly observed. Malignant solitary fibrosis tumors of the urinary bladder, however, are very rare. As there are no pathognomonic features of malignancy, surgical resection is often both diagnostic and therapeutic, as was the case in our report.

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.

• Abdominal imaging
• Solitary fibrous tumors
• Computed tomography
• Magnetic resonance imaging

• Abdominal Neoplasms/chemistry
• Abdominal Neoplasms/diagnosis
• Abdominal Neoplasms/diagnostic imaging
• Abdominal Neoplasms/pathology
• Adult
• Aged
• Biomarkers, Tumor/analysis
• Biopsy
• Female
• Humans
• Immunohistochemistry
• Infant
• Magnetic Resonance Imaging
• Male
• Middle Aged
• Multimodal Imaging
• Pelvic Neoplasms/chemistry
• Pelvic Neoplasms/diagnosis
• Pelvic Neoplasms/diagnostic imaging
• Pelvic Neoplasms/pathology
• Predictive Value of Tests
• Retrospective Studies
• Solitary Fibrous Tumors/chemistry
• Solitary Fibrous Tumors/diagnosis
• Solitary Fibrous Tumors/diagnostic imaging
• Solitary Fibrous Tumors/pathology
• Tomography, X-Ray Computed
• Tumor Burden

• Soft tissue neoplasms
• anus
• rectum
• sarcoma
• surgery