The utility of 18F-FDG PET/CT in solitary fibrous tumors of the pleura

18F-FDG PET/CT characteristics of solitary fibrous tumour of the pleura: single institution experience

BACKGROUND

To date, published studies have shown that ¹⁸F-FDG PET/CT and CT have limited value in differentiating benign and malignant solitary fibrous tumours of the pleura (SFTP). This study aimed to determine whether the metabolic and morphological characteristics of ¹⁸F-FDG PET/CT can be a valuable addition to diagnostic tools for SFTPs.

METHODS

From January 2016 to November 2021, we performed a retrospective review in 32 SFTPs patients who underwent ¹⁸F-FDG PET/CT scan. All the SFTP diagnoses were confirmed by surgical resection or biopsy samples. The metabolic parameters (including SUVmax, SUVmean, MTV, TLG, and SULmax) were obtained from ¹⁸F-FDG PET/CT images.

RESULTS

Thirty-two patients with SFTP were consecutively identified. The malignant SFTPs have higher Ki-67 expression (P = 0.005). The study observed that tumour heterogeneity without contrast injection (P = 0.001) and intratumor blood vessels (P = 0.047) were morphological features associated with malignant SFTP. Malignant SFTP was more frequently observed with higher SUVmax values (P = 0.001), higher SUVmean values (P = 0.001), higher TLG values (P = 0.006), and higher SULmax values (P < 0.001). For predicting malignant SFTP, the AUC values of SUVmax, SUVmean, TLG, and SULmax obtained by the area under curve analysis were 0.970 (95% CI 0.907-1.000; P = 0.001), 0.874 (95% CI 0.675-1.000; P = 0.009), 0.807 (95% CI 0.654-0.961; P = 0.031), and 0.911 (95% CI 0.747-1.000; P = 0.004), respectively.

CONCLUSION

The study showed that metabolic and morphological features were useful for distinguishing malignant from benign SFTPs.

Severe hypoglycemia and finger clubbing in a patient with a BRCA1 mutation in a solitary fibrous tumor: a case report

Solitary fibrous tumors (SFTs) are rare tumors that stem from mesenchymal cells of submesothelial tissues belonging to the pleura. They can occur in many places such as the spinal canal, intracranial, neck, kidney, liver, pelvis, limbs and other places, most commonly in the chest and abdomen. Pleural SFTs are one of the most common types, and are common in middle-aged people. Pleural SFTs can have an insidious expression, such that the illness can progress for years before diagnosis. SFTs can induce paraneoplastic syndromes, such as reactive hypoglycemia [Doege-Potter syndrome (DPS)] or hypertrophic osteoarthropathy [Pierre-Marie-Bamberger syndrome (PMBS)]. In this article, we report a case study of a 51-year-old man with pleural SFTs. Preoperative imaging examinations, including chest X-ray, computed tomography (CT), and magnetic resonance imaging (MRI), showed a huge mass in the right thoracic cavity, compressing surrounding tissues and organs and may invade other tissues. In addition, he suffers from severe hypoglycemia and finger clubbing, and has successfully undergone a complete resection, and now attends regular follow-up appointments. The paraneoplastic syndromes have resolved, and no recurrence has been found. Importantly, we used next-generation sequencing (NGS) to explore the molecular characteristics of the patient’s pathological tissue at the DNA level and mRNA level, and found that breast cancer gene 1 (BRAC1) mutations may be an important pathogenic factor.

A Comprehensive Review on Solitary Fibrous Tumor: New Insights for New Horizons

Simple Summary

Solitary fibrous tumor (SFT) is a malignant condition that exhibits different clinical behaviors ranging from low to high aggressive SFT, with dedifferentiated SFT (DD-SFT) being the fastest-growing subtype. Even when surgery alone provides curation rates above 60%, recurrences do occur in a fraction of patients where surgery is unable to provide disease control. Among the systemic therapeutic options, antiangiogenic compounds have shown higher efficacy than chemotherapy by indirect comparisons. Furthermore, rotating different antiangiogenics, at the progression time, has been shown to be effective. The exception is DD-SFT since it is resistant to antiangiogenics but can respond to chemotherapy. This comprehensive review also analyzes the underlying molecular components that play a key role in SFT origin and aggressiveness. The discovery in 2013 of anomalous fusion genes between NAB2 and STAT6 was determinant to increase the knowledge on the molecular drivers in SFT that could be potential targets for future therapies.

Abstract

Solitary fibrous tumor (SFT) is a rare mesenchymal, ubiquitous tumor, with an incidence of 1 new case/million people/year. In the 2020 WHO classification, risk stratification models were recommended as a better tool to determine prognosis in SFT, to the detriment of “typical” or “malignant” classic terms. The risk for metastasis is up to 35–45%, or even greater, in series with a longer follow-up. Over the last few decades, advances in immunohistochemistry and molecular diagnostics identified STAT6 nuclear protein expression and the NAB2–STAT6 fusion gene as more precise tools for SFT diagnosis. Recent evidence taken from retrospective series and from two prospective phase II clinical trials showed that antiangiogenics are active and their sequential use from first line should be considered, except for dedifferentiated SFT for which chemotherapy is the best option. Since the fusion transcript driver’s first description in 2013, new insights have been brought on key molecular events in SFT. This comprehensive review mainly focuses on the superior efficacy of antiangiogenics over chemotherapeutic agents in SFT, provides the current knowledge of key molecules that could co-drive the SFT behavior, and suggests new target candidates that deserve to be explored in preclinical and clinical research in SFT.

Locally advanced malignant solitary fibrous tumour successfully treated with conversion chemotherapy, operation and postoperative radiotherapy: a case report

Preoperative diagnosis of solitary fibrous tumour (SFT) may not provide a complete tumour picture and may be inaccurate. There is no standard treatment for locally advanced or metastasised malignant SFT (MSFT). Here, the case of a 17-year-old male patient with final pathology diagnosis of MSFT is reported. Preoperative biopsy pathology results suggested an Ewing sarcoma that was positive for CD99 antigen, vimentin, friend leukaemia integration 1 transcription factor, apoptosis regulator Bcl-2, and synaptophysin; and negative for CD34 antigen, S-100 protein (S-100), smooth muscle antigen, cytokeratin, and Wilms tumour 1 associated protein. The Ki67 positive rate was 8%, so the patient initially received eight cycles of conversion chemotherapy (vincristine, etoposide, ifosfamide and pirarubicin for one cycle, and vincristine, doxorubicin, and cyclophosphamide/ifosfamide and etoposide for 7 cycles in total). The tumour shrunk significantly and was surgically removed. The final pathology diagnosis was MSFT that was positive for CD99 and signal transducer and activator of transcription 6, and negative for CD34, tumour protein 63, S-100, desmin, and epithelial membrane antigen. Fluorescence in situ hybridization showed no gene translocation in EWS RNA binding protein 1, SS18 subunit of BAF chromatin remodelling complex or FUS RNA binding protein. The patient finally accepted adjuvant radiotherapy of 5600 cGy. Disease-free survival has been > 1 year, with no recurrence or metastasis detected to date. MSFT is rare and treatment for locally advanced or metastatic MSFT remains controversial. The efficacy of the present therapeutic strategy requires further research.

Rapidly growing solitary fibrous tumors of the pleura: a case report and review of the literature

A solitary fibrous tumor (SFT) is a rare spindle cell tumor-derived from mesenchymal cells. It may be linked to the fusion of the NAB2-STAT6 gene caused by 12q chromosome rearrangement. It can occur in the connective tissue of any part of the body; however, it is most common in the pleura. Solitary fibrous tumors of the pleura (SFTP) are a persistent painless mass with slow growth. With the increase of the tumor, there will be corresponding compression symptoms. Pleural effusion is rare, and the cytology of pleural effusion is mostly negative. Occasionally, SFTP can induce paraneoplastic syndrome, distant metastasis, and malignant transformation. Lung function may have mild to moderate restrictive ventilation dysfunction. CT is a crucial method for the clinical diagnosis of SFTP. The histopathological features of SFTP are the coexistence of sparse and dense areas. CD34, CD99, Bcl-2, and vimentin are the most valuable immunohistochemical markers.The positive expression rate of STAT6 in benign SFT was even 100%. Adhesion or unclear boundary with surrounding tissues, pleural effusion or calcification, tumors with a maximum diameter greater than 10 cm, invasive growth, uneven density, metastasis or recurrence, paraneoplastic syndrome, moderate to severe cell heterogeneity, high Ki67 proliferation index, and low STAT6 expression suggest SFTP may be a malignant tumor. Gene analysis on next generation sequencing may help reveal the mutation characteristics of SFTP. Complete tumor resection is the gold standard of SFTP. Resectability is the most important prognostic factor. Age, size, mitosis, and necrosis are considered risk stratification factors for prognosis. Fortunately, 80% of SFTP are benign and have anexcellentprognosis but need long-term follow-up.We report a case of rapidly growing tumor with pleural effusion within 9 months, who was surgically treated and is currently under follow-up. And the literature is reviewed.

Malignant solitary fibrous tumor of the pancreas with systemic metastasis: A case report and review of the literature

BACKGROUND

Pancreatic solitary fibrous tumor (SFT) is a rare neoplasm of intermediate biological potential. So far, only 22 cases have been reported since 1999. All the cases, except one, exhibited benign features. Here, we report the first case of malignant pancreatic SFT with typical Doege-Potter syndrome, along with the clinical and pathologic evidence of its systemic metastasis.

CASE SUMMARY

The patient was a 48-year-old man with a 1-year history of pancreatic and liver masses and refractory hypoglycemia. Increased uptake of the tracer fluorodeoxyglucose (FDG) was found in the liver and bones by fluorine-18 FDG positron emission tomography/computed tomography. After multidisciplinary discussion, a distal pancreatectomy procedure was performed, and histological examination showed a lesion composed of abundant heterogeneous spindle cells with localized necrosis. On immunohistochemistry evaluation, STAT6 was found to be diffusely expressed in the tumor. Based on the overall evidence, the patient was diagnosed with malignant pancreatic SFT with liver and bone metastases.

CONCLUSION

The diagnosis of malignant SFT requires comprehensive evidence including clinical, immunohistochemistry, and histological features. This case may be presented as a reference for diagnoses and management of malignant pancreatic SFTs with systemic metastasis.