Fibroblast Activation Protein α-Directed Imaging and Therapy of Solitary Fibrous Tumor

Fibroblast activation protein α (FAPα) is expressed at high levels in several types of tumors. Here, we report the expression pattern of FAPα in solitary fibrous tumor (SFT) and its potential use as a radiotheranostic target. Methods: We analyzed FAPα messenger RNA and protein expression in biopsy samples from SFT patients using immunohistochemistry and multiplexed immunofluorescence. Tracer uptake and detection efficacy were assessed in patients undergoing clinical 68Ga-FAPα inhibitor (FAPI)-46 PET,18F-FDG PET, and contrast-enhanced CT. 90Y-FAPI-46 radioligand therapy was offered to eligible patients with progressive SFT. Results: Among 813 patients and 126 tumor entities analyzed from the prospective observational MASTER program of the German Cancer Consortium, SFT (n = 34) had the highest median FAPα messenger RNA expression. Protein expression was confirmed in tumor biopsies from 29 of 38 SFT patients (76%) in an independent cohort. Most cases showed intermediate to high FAPα expression by immunohistochemistry (24/38 samples, 63%), which was located primarily on the tumor cell surface. Nineteen patients who underwent 68Ga-FAPI-46 PET imaging demonstrated significantly increased tumor uptake, with an SUVmax of 13.2 (interquartile range [IQR], 10.2), and an improved mean detection efficacy of 94.5% (SEM, 4.2%), as compared with 18F-FDG PET (SUVmax, 3.2 [IQR, 3.1]; detection efficacy, 77.3% [SEM, 5.5%]). Eleven patients received a total of 34 cycles (median, 3 cycles [IQR, 2 cycles]) of 90Y-FAPI-46 radioligand therapy, which resulted in disease control in 9 patients (82%). Median progression-free survival was 227 d (IQR, 220 d). Conclusion: FAPα is highly expressed by SFT and may serve as a target for imaging and therapy. Further studies are warranted to define the role of FAPα-directed theranostics in the care of SFT patients.

[Transoral robotic surgery in the management of solitary fibrous tumor at the entrance of the hypolaryngeal esophagus: a case report and literature review]

To explore the clinical diagnosis and treatment experience of isolated fibrotic tumor （SFT） occurring in the larynx, hypopharynx and esophageal inlet with a wide range.The patient, admitted to the Department of Otolaryngology-Head and Neck Surgery of Tangdu Hospital of Air Force Medical University was a female aged at 78 years, who was diagnosed with SFT primarily occured at laryngeal, hypopharynx and esophageal entrance. The clinical data, surgical methods, histopathology characteristics of the patient were analyzed respectively. It's proved that a tumor sized about 3.8 cm×2.8 cm×2.0 cm with slippy surface was found at the entrance of the laryngeal, hypopharynx and esophageal entrance, covering the laryngeal vestibule, glottis and right piriform fossa, which was completely resected by transoral robotic surgery. The postoperative pathological diagnosis was SFT. The patient recovered well after surgery and showed no recurrence within 16-month follow-up. SFT occurring in the larynx, hypopharynx, and esophageal inlet is very rare, and transoral da Vinci robotic surgical resection of the tumor in this area is feasible, and has the advantages of clear field of vision, less bleeding, less trauma, fewer complications, and quicker postoperative recovery.

Giant cell-rich solitary fibrous tumour of the urinary bladder: case report of an unusual histological variant and literature review

BACKGROUND

Giant cell-rich solitary fibrous tumour (GCR-SFT), previously referred to as giant cell angiofibroma, is an uncommon soft tissue tumour that classically occurs in the orbit but very rarely presents in deep organs. Here, we present a case of GCR-SFT occurring in the urinary bladder, which is one of the unusual histological subtypes of SFT.

CASE PRESENTATION

A 56-year-old man was incidentally found to have a mass measuring 4.5 × 4.3 × 4.0 cm located in the left posterior wall of the bladder by computed tomography during a physical examination. The lesion was confirmed as GCR-SFT by pathological examination after laparoscopic radical surgery. Histopathologically, the tumour was a well-circumscribed, nonencapsulated lesion that was composed of bland spindle-ovoid tumour cells alternating with hypocellular and hypercellular areas, staghorn-like vasculatures and scattered large dark-stained multinucleate giant cells lining pseudovascular spaces. The spindle-ovoid cells and multinucleate giant cells showed strong and diffuse expression of CD34 and nuclear STAT6. In addition, the hallmark of the NAB2ex4-STAT6ex5 fusion gene was detected by RT‒PCR. The patient was classified as having a low risk of recurrence or metastasis according to the risk stratification criteria. The patient underwent regular follow-up for 34 months after surgery, and there was no evidence of local recurrence or metastasis.

CONCLUSION

This is the first reported case of GCR-SFT occurring in the urinary bladder with underlying NAB2ex4-STAT6ex5 fusion. Complete surgical excision of the tumour and long-term follow-up are recommended to ensure no local recurrence or metastasis.

Mesenchymal tumours of the pleura: review and update

Primary mesenchymal tumours of the pleura are uncommon and can be diagnostically challenging due to their overlapping histopathologic and immunophenotypic features. Herein we discuss selected mesenchymal tumours of the pleura, including solitary fibrous tumour, calcifying fibrous tumour, desmoid fibromatosis, synovial sarcoma, schwannoma, malignant peripheral nerve sheath tumour, inflammatory myofibroblastic tumour, follicular dendritic cell sarcoma, epithelioid hemangioendothelioma, and desmoplastic small round cell tumour. We review their clinicopathologic characteristics, along with an update on the relevant immunohistochemical and molecular features.

Solitary Fibrous Tumor of the Prostate Treated with Frozen-Section Supported Robot-Assisted Nerve-Sparing Radical Prostatectomy

INTRODUCTION

Solitary fibrous tumors (SFTs) of the prostate are extremely rare. We report on a 60-year-old man who was diagnosed with prostatic SFT through transurethral resection (TUR) of the prostate, and we provide a narrative literature review to put the case into perspective. We looked into multiple databases for articles published before June 2022.

CASE REPORT

A 60-year-old man without comorbidities presented with acute urinary retention and significant macrohematuria. Due to recurrent bladder tamponades and relevant blood loss despite irrigation, an emergency endoscopic transurethral evaluation was initiated. Intraoperatively, diffuse venous hemorrhage from prostatic vessels around the bladder neck was detected, as well as significant hemorrhage from a grossly enlarged and tumor-suspicious prostate middle lobe. Within the framework of extensive bipolar coagulation, parts of the suspicious middle lobe were removed via TUR. The final histopathology report showed incompletely resected SFT of the prostate. Due to the extremely rare SFT diagnosis, the case was discussed in an interdisciplinary tumor board and further diagnostic workup, including thoracoabdominal computed tomography and magnetic resonance imaging of the pelvis, was performed, which revealed no secondary tumors or signs of metastasis. According to the tumor board recommendation, robot-assisted radical prostatectomy (RARP) with bilateral nerve sparing was performed, supported by intraoperative frozen section. The final histopathology confirmed the SFT that had developed from the transition zone. The SFT was resected with negative frozen section result and negative surgical margins (R0). No intra- and perioperative complications occurred, and in the short-term follow-up, the patient presented in excellent general status with full continence. From 1997 to June 2022, we identified a total of 12 publications reporting on treatment for prostatic SFT (11 case reports and 2 patient series), with none performing bilateral nerve sparing, frozen section, or robot-assisted radical prostatectomy. No common survival endpoints were accessible.

CONCLUSION

This case demonstrates the exceedingly rare case of SFT of the prostate, which has been described in the literature in only 23 men worldwide. Here, we were the first to demonstrate the feasibility of bilateral nerve-sparing RARP supported by frozen section. A systematic review was not possible due to the lack of common endpoints.

Identification of dual STRN-NTRK2 rearrangements in a high grade sarcoma, with good clinical response to first-line larotrectinib therapy

BACKGROUND

Among the three NTRK genes, NTRK2 possesses a tremendous structural complexity and involves tumorigenesis of several types of tumors. To date, only STRN and RBPMS are identified in the fusion with NTRK2 in adult soft tissue tumors. More recently, the highly selective Trk tyrosine kinases inhibitors, including larotrectinib and entrectinib, have shown significant efficacy for treating tumors harboring NTRK fusions and were approved by FDA.

CASE PRESENTATION

We report a case of sarcoma in a 35-year-old female harboring two STRN-NTRK2 gene fusions, with a good clinical response to first-line larotrectinib treatment. Core biopsy of the 16.5 cm gluteal mass showed a high-grade mesenchymal neoplasm with features reminiscent of a solitary fibrous tumor, but negative for STAT6. In-house next-generation sequencing gene fusion panel showed two in-frame STRN-NTRK2 fusions, which contain the same 5' partner sequence (exon 1-3) of STRN, and the 3' fusion partner starting from either the exon 15 or the exon 16 of NTRK2. Due to the large size and location of the tumor, first-line neoadjuvant therapy with larotrectinib was initiated. The patient has an excellent clinical response with an 83% tumor size reduction by imaging. The tumor was subsequently completely resected. After 130 days, larotrectinib was reinitiated for lung metastasis (up to 7 cm), and a complete resolution was achieved. When compared with NTRK1 and NTRK3, NTRK2 fusions are the least common. Of note, the only other report in the literature on NRTK2 fusion-positive sarcoma also showed solitary fibrous tumor (SFT)-like morphology, and the patient responded well to larotrectinib as the second line adjuvant therapy.

CONCLUSIONS

In conclusion, the identification of NTRK2 fusions in patients with soft tissue tumors could significantly improve the clinical outcome through selective NTRK inhibitor therapy, especially in the first-line setting. Prompt RNA-based NGS testing at initial diagnosis may benefit these patients. Our case is among the first few in the literature on NTRK2 fusion sarcoma with first-line larotrectinib therapy in the primary and metastatic setting, with good clinical response and minimal side effects.

Solitary fibrous tumor of head and neck region; A clinicopathological study of 67 cases emphasizing the diversity of histological features and utility of various risk stratification models

BACKGROUND

Head and neck SFT (HNSFT) exhibit diverse histological features and can mimic various neoplasms with different treatment and behavior. While risk stratification systems have been developed for this tumor at various anatomic sites, a specific scheme for head and neck tumors is lacking. Our aim was to describe the histologic patterns present in HNSFT cases as well as assess the utility of risk assessment models in this location.

METHODS

A retrospective review of pathology reports and microscopy glass slides of HNSFT cases diagnosed between January 2010 and August 2022 was performed.STAT6 was additionally performed on selected cases if needed. Follow up was obtained and various risk stratification models were applied.

RESULTS

Sixty seven cases of HNSFT were collected (age range from 11 to 87 years; median 42 years; M:F 1.6:1). Most common tumor sites were orbit (n = 21; 31.3 %), sinonasal tract (n = 18; 26.9 %), and oral cavity (n = 13; 19.4 %). Tumor size ranged from 1 to 16 cm (median 4cm). Apart from common histological features, tumor cells also showed focal epithelioid morphology, clear cell change and nuclear atypia in a subset of cases. Stromal findings included myxoid and lipomatous change, pseudoglandular spaces, pseudovascular spaces and multinucleated stromal giant cells. CD34 and STAT6 were expressed in 57/67 (85.1 %) and 56/56 (100 %) cases, respectively. Recurrence was observed in 4/26 (15.4 %) cases, while none (0/22) of the patients experienced distant metastasis (follow up 1-150 months; median 20.5 months). Clinical outcome was partially concordant with risk-categories of different risk stratification models.

CONCLUSION

Knowledge about histological diversity of HNSFT is essential for establishing correct diagnosis. Current risk stratification models do not perfectly predict outcome, and larger studies are needed to develop more accurate criteria for aggressive behavior.

[Classification and Molecular Diagnosis of Benign Brain Tumors]

Classification and molecular diagnosis of benign brain tumors, focusing on cranial and pasaspinal nerve tumors, meningioma, mesenchymal, and non-meningothelial tumors involving the central nervous system(CNS)has been reviewed based on the 5th edition of the World Health Organization Classification of Tumors of the Central Nervous System. In sporadic schwannomas, the novel fusion gene SH3PXD2A-HTRA1, which activates the MAPK pathway, has been discovered. Meningioma shows frequent chromosomal alterations, including at the NF2 locus. Recent genomic studies have investigated mutations in TRAF7, KLF4, AKT1, and SMO in sporadic meningiomas. In the 5th edition, the meningioma should be graded regardless of the subtype. Thus, TERT promoter mutation and homozygous deletion of CDKN2A/B should be evaluated to define grade 2 and 3 meningiomas. In mesenchymal tumors, the term "hemangiopericytoma" has been deleted from solitary fibrous tumors.

Acute periocular haemorrhage associated with severe proptosis as a presenting sign of orbital tumours

Periocular haemorrhage without a preceding history of trauma, and in the absence of vascular malformations is rare. While acute proptosis is well described in the setting of orbital pathology, accompanying periocular haemorrhage has been rarely reported. We describe three cases with these concomitant presenting signs in orbital malignancies - metastatic small cell bladder carcinoma, haemangiopericytoma (solitary fibrous tumour) and myeloma. Clinical photographs and radiology are presented with review of the current literature. All cases had an associated rapid onset of severe proptosis and co-existing periocular bruising on the same side. The presence of ecchymosis of the eyelids in addition to proptosis without a history of trauma warrants thorough investigation to rule out underlying potential sight and life threatening illness.

68 Ga-DOTATOC PET/CT Imaging of a Muscular Solitary Fibrous Tumor

ABSTRACT

A 73-year-old woman was referred for 68 Ga-DOTATOC PET/CT staging of a grade 2 pancreatic neuroendocrine tumor, which showed the primary pancreatic tumor, liver metastases, one left pleural metastasis, and high uptake in a mass of the right triceps brachii muscle. Two years before, she underwent 18 F-FDG PET/CT and 111 In-pentetreotide scan, respectively, with low and high uptake of each radiotracer in the triceps mass. Histopathological analysis revealed a solitary fibrous tumor. Immunohistochemistry showed no staining for SSTR-2 and SSTR-5, suggesting tumor overexpression of another somatostatin receptor. This case highlighted a potential pitfall on 68 Ga-DOTATOC PET/CT.

Abdominopelvic Hemangiopericytoma Mimicking Neuroendocrine Tumor on 68 Ga-DOTANOC PET/CT

ABSTRACT

We present the case of a 60-year-old man who was being evaluated for 2 intra-abdominal masses. The masses were tracer avid on 68 Ga-DOTANOC PET/CT and were suggestive of neuroendocrine tumor. Histopathology, however, confirmed the masses to be hemangiopericytoma. Hemangiopericytoma comes under the umbrella of solitary fibrous tumors, a rare tumor group arising from the mesenchymal cells. Solitary fibrous tumors commonly arise from the pleura but can occur anywhere in the body. Intra-abdominal hemangiopericytoma are extremely rare and should be kept in mind as one of the differential diagnoses for 68 Ga-DOTA peptide-avid tumors.

68 Ga-PSMA-Avid Intranasal Solitary Fibrous Tumor

ABSTRACT

The utility of molecular imaging in solitary fibrous tumors has not been fully established. We present a rare case of recurrent intranasal solitary fibrous tumor incidentally localized on 68 Ga-PSMA PET/CT scan, which turned out to be metabolically inactive on 18 F-FDG PET/CT.

[Solitary fibrous tumor in choroid: a clinicopathologic analysis of two cases]

Solitary fibrous tumor (SFT) is an uncommon spindle cell tumor that occurs mainly in the pleura, but also in other parts of the body. Intraocular SFT is very rare. This paper reports 2 cases of choroidal SFT which were diagnosed by clinical, imaging, histopathological and immunohistochemical staining. The patient remained asymptomatic with no sign of recurrence and metastasis after operation.

Targeting-intratumoral-lactic-acidosis transcatheter-arterial-chemoembolization for non-islet cell tumor hypoglycemia secondary to a liver metastatic solitary fibrous tumor: A case report and literature review

Doege-Potter syndrome is a rare paraneoplastic syndrome characterized by non-islet cell tumor hypoglycemia secondary to a solitary fibrous tumor. Doege-Potter syndrome always presents with recurrent fasting hypoglycemia, which can occasionally be life-threatening. The best choice of treatment for Doege-Potter syndrome and solitary fibrous tumor is complete resection. However, when it is unfeasible, local-regional treatment can be used as a palliative therapy. Herein, we report a case of a 46-year-old man with Doege-Potter syndrome that occurred secondary to the liver and pancreatic metastatic solitary fibrous tumors. After he received six rounds of targeting-intratumoral-lactic-acidosis transcatheter-arterial-chemoembolization (TILA-TACE) treatment in our hospital, his hypoglycemia was clinically cured, and the liver metastatic tumor was well controlled. We suggest that TILA-TACE can be considered when curative resection is unfeasible for metastatic liver solitary fibrous tumors to help a patient obtain further surgery opportunities.

Solitary Fibrous Tumors of the Pleura Shown on 18F-FDG and 68Ga-DOTA-FAPI-04 PET/CT

ABSTRACT

A 52-year-old man complained of pain in the right lower chest wall for a month. Chest CT found a subpleural mass, but failed to identify the nature of the tumor. The 18F-FDG PET/CT was conducted for further diagnosis and staging, which showed the mass in the lower lobe of the right lung with mild radioactive uptake of 18F-FDG. The patient was subsequently enrolled in an ongoing clinical trial using 68Ga-DOTA-FAPI-04 (fibroblast activation protein inhibitor) PET/CT. The mass showed intensive 68Ga-DOTA-FAPI-04 uptake, which was subsequently confirmed as solitary fibrous tumors of the pleura by pathology. Our case demonstrated that the 68Ga-DOTA-FAPI-04 might have excellent tumor affinity of solitary fibrous tumors of the pleura.

[A Case of Solitary Fibrous Tumor of the Liver]

Most solitary fibrous tumors(SFT)occur in the thoracic cavity and reports on liver SFT are very rare. We encountered a case of SFT of the liver, and thus, decided to report it with a review of literature. A 70-year-old man was informed of a liver tumor by his previous doctor and referred to us for further examination and treatment. Contrast-enhanced CT revealed a 3.5 cm cyst in the S2/3 of the liver and a 3.2 cm tumor with an early staining within the cyst. Laparoscopic lateral segmentectomy was performed and a diagnosis of hepatic cystic adenocarcinoma was made. Macroscopically, the tumor was white and welldefined. Histopathological examination revealed round chromatin-enriched tumor cells proliferated with round fibrillar cells or intercalated structures consisting of round or short spindle-shaped cells. Immunohistochemistry yielded negative results for CAM5.2, HepPar1, CD31, CD99, SMA, and HMB45 but positive results for CD34, Factor Ⅷ, Bcl-2, and STAT6; therefore, the patient was further diagnosed with liver SFT. Although liver SFT is rare, it was considered a differential diagnosis when multiple bloody liver tumors were detected. In addition, since there were reports of recurrence, careful follow-up in future, was deemed necessary.

[A case of solitary fibrous tumor from the greater omentum resected via laparoscopic surgery]

Solitary fibrous tumor (SFT) are relatively rare neoplasms that usually arise in the thoracic cavity in adults. Although many cases of extrathoracic SFT have been recently reported, SFT from the omentum is rare. A 32-year-old woman consulted a gynecologist complaining of irregular vaginal bleeding. Magnetic resonance imaging (MRI) revealed a tumor in the omentum, and the patient was admitted to our department. The patient underwent laparoscopic tumorectomy. The tumor size was 48 × 35 × 30 mm, and grayish-white nodules were observed. Histological examination showed hyperplastic spindle-shaped tumor cells with a pattern-less arrangement. Immunohistochemical staining showed the tumor was positive for CD34 and bcl-2, slightly positive for alpha smooth muscle actin(a-SMA), and negative for S-100 and c-kit. Accordingly, a diagnosis of SFT was made. The patient has not shown any recurrence 12 months after surgery. Most SFTs are benign, although there are some reports of recurring tumors. There are no clear guidelines for the treatment of SFT because of its rarity. Therefore, close long-term follow-up should be performed.

[Extrapleural solitary fibrous tumor in nose: 2 cases report and review of literature]

OBJECTIVE

To analyze the clinical characteristics, imaging features, pathological findings, treatment and prognosis of the extrapleural solitary fibrous tumor (EPSFT) in nose, and then to improve the quality of diagnosis and treatment of EPSFT.

METHOD

Clinical data of two patients with EPSFT were collected in recent 2 years. All the information, including clinical symptoms, imaging characteristics, blood routine, serum biochemical, treatment options, pathological immunohistochemical findings, and following-up results were reported and analyzed, and the clinical features of EPSFT in the nose were summarized with review of the literature.

RESULT

(1) The main clinical characteristics were nasal obstructive and epistaxis. (2)There were no imaging differences essentially between EPSFT and other tumors in nasal cavity. In terms of enhancement CT scanning, the image manifestations of EPSET were similar to that of hemangioma to a certain degree in nasal cavity. (3) Routine blood and serum biochemical test were normal in the patients with EPSFT in the nose. (4)Confirmed diagnosis mainly depended on pathological and immunohistochemical findings. (5) These two patients underwent surgical treatment, and the tumors were en bloc resected, and were in full recovery. Follow-up time is 2 years in one case and the other one is 1 year. No recurrence or metastasis were found in these two patients.

CONCLUSION

DSA and vascular embolism is recommended before surgical treatment in some patients. En bloc resection is the preferred treatment option with definite curative effect for the patients with EPSFT in nose, and the prognosis is favorable.

[Atypical solitary fibrous tumor of the buccal mucosa: report of 1 case]

Solitary fibrous tumor is often considered to be a mesenchymal tumor. We reported a case of atypical SFT of the buccal mucosa in a 56-year-old male patient. We found hypercellularity, nuclear atypia, increased number of mitotic figures(more than 4 per 10 high-power fields) microscopically. A long-term follow-up is necessary after complete excision.

[Solitary fibrous tumor of endometrium--a case report]

OBJECTIVE

Solitary fibrous tumor (SFT) is an uncommon mesenchymal tumor. We present a case of SFT occurring in endometrium.

DESIGN

Case report.

SETTING

Department of Obstetrics and Gynecology, The Fingerland Department of Pathology, Medical Faculty of Charles University and Faculty Hospital Hradec Králové.

CASE REPORT

We report a case of 57 years old woman with SFT arising from the endometrium, which was diagnosed and treated at our department. Histological finding was supported by typical immunohistochemical profile of the tumor. Aggressive nature of the tumor wasnt showed. The patient underwent abdominal hysterectomy with bilateral adnexectomy and is followed up in regular periods.

CONCLUSION

Occurence of solitary fibrous tumor (SFT) in the female genital tract is extremely rare. To the best of our knowledge, we report the first case of SFT occurring in endometrium. Because of potencial aggressive behaviour of the tumor complete surgical excision and close follow-up is highly recommended.