Radiology–Pathology Conference: 18F FDG PET-CT imaging of solitary fibrous tumor of the pleura

Solitary fibrous tumor of the seminal vesicle

Solitary fibrous tumors (SFTs) are mesenchymal neoplasms with variable clinical behavior depending on age, tumor site, and size, and pathologic factors such as mitoses and necrosis. Imaging features on computed tomography (CT) or magnetic resonance imaging (MRI) are not specific, and the diagnosis relies on histopathology with immunohistochemistry. SFTs arising from seminal vesicles is rare and reported in only eight earlier cases. We discuss the clinical, histopathologic and positron emission tomography (PET) imaging characteristics of a 54-year-old patient with SFT of the seminal vesicle. The patient was treated with robot-assisted seminal vesiculotomy and is doing well on follow-up at two years.

The 68 Ga-DOTA-FAPI-04 PET/CT for the differential diagnosis of solitary fibroma of pleura from other chest disease with low uptake of 18 F-FDG

OBJECTIVE

We conducted a prospective study using 68 Ga-DOTA-FAPI-04 PET/computed tomography (CT) to differentiate solitary fibromas of pleura (SFP) from other chest similar masses showing low uptake of 18 F-FDG.

METHODS

A prospective study including 13 patients was divided into two groups: five cases of SFP and eight of thoracic lesions resembling SFP on general imaging examination. Except for CT and MRI, all patients underwent both 18 F-FDG and 68 Ga-DOTA-FAPI-04 PET/CT examinations. Compare the differences of lesions in CT net enhancement value and the uptake of 18 F-FDG and 68 Ga-DOTA-FAPI-04 between the two groups. The values of CT and PET/CT for differential diagnosis were calculated by receiver operating characteristic (ROC) curves.

RESULTS

The uptake of 68 Ga-DOTA-FAPI-04 in SFP was significantly higher than the others in chest, SUVmean (8.10 ± 5.57) versus (1.11 ± 0.38); and SUVmax (15.46 ± 8.16) versus (3.96 ± 2.43), and the difference was statistically significant ( P < 0.05). The 68 Ga-DOTA-FAPI-04 could effectively distinguish SFP from other lesions, and the accuracies of SUVmax and SUVmean for differential diagnosis were 92.31 and 100%, the corresponding cutoff value being 7.19 and 2.26. The uptake of 18 F-FDG in SFP was slightly lower than other lesions, SUVmean (1.63 ± 0.30) versus (1.88 ± 1.02); and SUVmax (2.51 ± 0.54) versus (3.60 ± 1.57), and the difference was not statistically significant ( P > 0.05). The SFP showed significant enhancement in the venous phase, but the difference was not statistically significant ( P > 0.05).

CONCLUSION

The 68 Ga-DOTA-FAPI-04 has potential application value in differentiating SFP from lesions with low 18 F-FDG uptake, in addition, 68 Ga-DOTA-FAPI-04 may specifically target SFP.

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.

Solitary fibrous tumor: molecular hallmarks and treatment for a rare sarcoma

Solitary fibrous tumor (SFT) is a rare soft tissue sarcoma subtype which mainly affects adults in the fifth and sixth decades of life. Originally part of a spectrum of tumors called hemangiopericytomas, classification has been refined such that SFTs now represent a distinct subtype. The identification of NAB2-STAT6 fusion in virtually all SFTs has further aided to define this rare subgroup. SFTs have a spectrum of behavior from benign to malignant, with evidence suggesting risk of metastases related to age at diagnosis, extent of necrosis, mitotic rate and tumor size. The standard treatment for localized disease is surgical excision with or without radiotherapy. Retrospective and prospective evidence suggests antiangiogenic treatment is effective for unresectable disease. Further translational work is required to understand the biology driving the differential behavior and identify more effective treatments for patients with metastatic disease.

Implications of Adverse Biological Factors and Management of Solitary Fibrous Tumors of the Pleura

Solitary fibrous tumors arise in many locations throughout the body and are genetically and histologically considered a single disease. Solitary fibrous tumors of the pleura (SFTP) are the most common tumor of this disease. Most of the SFTPs are treated with surgery alone, and chemotherapy and radiotherapy do not seem to play a role in treatment. Tumor size and unfavorable histology are risk factors for malignant potential. Incomplete resection is an important risk factor for recurrence.

Intradural-Extramedullary Solitary Fibrous Tumor/Hemangiopericytoma with a Negative Result on Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography

Intradural-extramedullary solitary fibrous tumor/hemangiopericytoma (SFT/HPC) is a rare entity. SFT/HPCs can recur after surgery, even if a benign histology of the tumor is observed. We herein report a 68-year-old woman with intradural-extramedullary SFT/HPC. On magnetic resonance imaging (MRI), the intradural-extramedullary mass was isointense on T1-weighted images and hypointense on T2-weighted images with heterogeneous gadolinium enhancement. Whole-body fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG-PET/CT) was also performed, showing no accumulation. We performed surgery for the intradural-extramedullary mass, and the pathological findings of the resected specimen were a benign histology consistent with World Health Organization (WHO) grade I SFT/HPC. She had no evidence of tumor recurrence three years after the surgery for intradural-extramedullary SFT/HPC. 18F-FDG-PET/CT before surgery may be useful for predicting the postoperative behavior of spinal SFT/HPCs.

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.

Integrated therapeutic approach to giant solitary fibrous tumor of the pleura: report of a case and review of the literature

The fibrous tumors of the pleura are rare primary tumors, accounting for 5% of malignant pleural neoplasms, which generally originate from sub-mesothelial mesenchymal tissue of the visceral pleura. These tumours generally exhibit clinical benign behavior although 12% of solitary fibrous tumors can be malignant and have worse outcomes. These tumors are considered “giant” when the lesion > 15 cm. Surgical treatment is the best choice for both benign and malignant neoplasms. We retrospectively analyzed the main case series of giant fibrous tumors of the pleura. In addition we report our experience of a 76-year-old woman treated by pre-surgical embolization involving implantation of vascular plugs. Surgery was successfully carried out without complications; imaging and functional assessment 6 months post intervention demonstrated both the absence of recurrence and improvement of lung function parameters.

(18)F-FDG PET/CT imaging of malignant hepatic solitary fibrous tumor

Solitary fibrous tumor of the liver was rarely documented. F-FDG PET/CT imaging of malignant hepatic solitary fibrous tumor in a 49-year-old male patient was reported. The multifocal hepatic lesions demonstrated avid FDG uptake. FDG PET/CT might be potentially useful in the differentiation of benign and malignant solitary fibrous tumor.

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.