A malignant solitary fibrous tumour arising from the first lumbar vertebra and mimicking an osteosarcoma: a case report

An extremely rare case of an isolated primary benign pelvic Solitary Fibrous Tumor in an elderly female

INTRODUCTION AND IMPORTANCE

Solitary Fibrous Tumors are highly rare spindle cell tumors of mesenchymal origin. They comprise <2 % of all types of soft tissue tumors and are characterized by an age-adjusted annual incidence rate of 0.61 per 1 million individuals for extra-meningeal Solitary Fibrous Tumors. The disease course is mostly asymptomatic but can still present with non-specific symptoms. This results in misdiagnosis and delayed treatment. In turn, morbidity and mortality rises and it will constitute a clinical and surgical burden for the affected patients.

CASE PRESENTATION

We present the case of a 67-year-old female who has a known history of controlled hypertension, who presented to our hospital complaining of non-specific pain in her right flank and lower lumbar region. Our preoperative diagnostic radiological workup demonstrated an isolated antero-sacral mass.

CLINICAL DISCUSSION

Comprehensive excision of the mass was laparoscopically achieved. Following the necessary analysis via histopathology and immunohistochemistry, we definitively established the diagnosis of an isolated primary benign Solitary Fibrous Tumor.

CONCLUSION

To the best of our knowledge, no previous cases of SFTs from our country were documented. Clinical suspicion and complete surgical resection are vital determinants in treatment of such patients. Further research and documentation are warranted to set-up the necessary guidelines for preoperative assessment, intraoperative techniques, and adequate follow-up protocols to limit the ensuing morbidity and to detect any possible neoplastic recurrence.

Primary intraosseous solitary fibrous tumor: an extremely rare case report and brief review of the literature

Solitary fibrous tumor (SFT), a rare mesenchymal neoplasm of fibroblastic origin, was initially discovered in the mediastinal pleura and then described in many extra-pleural sites. The reports of primary solitary fibrous tumor of bone are extremely rare and only a few cases have been previously mentioned in the literature, most of which in flat and short bones.

Here we present the case of a 53-year-old female, who was referred to the emergency department of a peripheral hospital after an accidental fall. Imaging studies revealed an intertrochanteric fracture with an underlying intramedullary lytic lesion. A biopsy was performed and a diagnosis of Ewing sarcoma was initially suggested. She arrived at our hospital where we reevaluated the case. The biopsy was reviewed and a diagnosis of intraosseous SFT was proposed. She underwent en-block resection of the proximal right femur. Primary SFTs of the bone are, like in our case, easily misdiagnosed due to the low specificity of the imaging studies and the extreme rarity of the localization. An accurate diagnosis and early resection are very important and with careful long-term follow-up is essential, particularly in those who with malignant behavior, for the early detection of possible recurrence or metastasis.

Spinal Solitary Fibrous Tumors: An Original Multicenter Series and Systematic Review of Presentation, Management, and Prognosis

All solitary fibrous tumors (SFT), now histologically diagnosed by a positive nuclear STAT6 immunostaining, represent less than 2% of soft tissue sarcomas, with spinal SFT constituting a maximum of 2% of them, making these tumors extremely rare. We provide an up-to-date overview of their diagnosis, treatment, and prognosis. We included 10 primary STAT6-positive SFT from our retrospective cohort and 31 from a systematic review. Spinal pain was the most common symptom, in 69% of patients, and the only one in 34%, followed by spinal cord compression in 41%, radicular compression, including pain or deficit, in 36%, and urinary dysfunction specifically in 18%. Preoperative diagnosis was never obtained. Gross total resection was achieved in 71%, in the absence of spinal cord invasion or excessive bleeding. Histologically, they were 35% grade I, 25% grade II, and 40% grade III. Recurrence was observed in 43% after a mean 5.8 years (1 to 25). No significant risk factor was identified, but adjuvant radiotherapy improved the recurrence-free survival after subtotal resection. In conclusion, spinal SFT must be treated by neurosurgeons as part of a multidisciplinary team. Owing to their close relationship with the spinal cord, radiotherapy should be considered when gross total resection cannot be achieved, to lower the risk of recurrence.

Novel Therapeutic Options for Solitary Fibrous Tumor: Antiangiogenic Therapy and Beyond

SFT is an ultrarare mesenchymal ubiquitous tumor, with an incidence rate <1 case/million people/year. The fifth WHO classification published in April 2020 subdivided SFT into three categories: benign (locally aggressive), NOS (rarely metastasizing), and malignant. Recurrence can occur in up to 10-40% of localized SFTs, and several risk stratification models have been proposed to predict the individual risk of metastatic relapse. The Demicco model is the most widely used and is based on age at presentation, tumor size, and mitotic count. Total en bloc resection is the standard treatment of patients with a localized SFT; in case of advanced disease, the clinical efficacy of conventional chemotherapy remains poor. In this review, we discuss new insights into the biology and the treatment of patients with SFT. NAB2-STAT6 oncogenic fusion, which is the pathognomonic hallmark of SFT, is supposedly involved in the overexpression of vascular endothelial growth factor (VEGF). These specific biological features encouraged the successful assessment of antiangiogenic drugs. Overall, antiangiogenic therapies showed a significant activity toward SFT in the advanced/metastatic setting. Nevertheless, these promising results warrant additional investigation to be validated, including randomized phase III trials and biological translational analysis, to understand and predict mechanisms of efficacy and resistance. While the therapeutic potential of immunotherapy remains elusive, the use of antiangiogenics as first-line treatment should be considered.

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.

Pelvic cavity malignant solitary fibrous tumor with dedifferentiation and multifocal cytokeratin expression

Pelvic cavity small-sized malignant solitary fibrous tumors are rare. Surgeons easily misjudge these tumors as benign lesions, and they are usually resected by laparoscopic surgery. When accompanied by dedifferentiation, malignant solitary fibrous tumors are difficult to diagnose by pathologists. Here, we describe a challenging case. A 47-year-old man was accidentally found to have a pelvic mass after three months. Surgeons assumed a diagnosis of a benign tumor according to the Computed Tomography and Ultrasonography reports. The patient underwent laparoscopic surgery to resect the tumor. After the operation, the patient was diagnosed as having a malignant solitary fibrous tumor with dedifferentiation. The patient had a recurrence one year later. This pelvic cavity malignant solitary fibrous tumor was a rare case because of its dedifferentiation and cytokeratin expression. The expression of cytokeratin and the absence of vimentin and CD34 were pitfalls to diagnosis. In this case, there was still a high amount of malignancy despite the small size of the tumor. Clinical image and pathologic multidisciplinary analysis and core needle biopsies before surgery had a great effect on diagnosis and therapy of this disease. The case is a cautionary tale not only for pathologists but also for surgeons.

Intrapericardial solitary fibrous tumor: A case report and review of literature

Solitary fibrous tumor (SFT) is a mesenchymal neoplasm mostly originates from pleura, but rarely from other parts of the body including pericardium. We report a case of a 44-year-old woman with dyspnea and intermittent edema in whom a large intrapericardial mass was discovered by echocardiography. Computed tomography (CT) revealed a focal pericardial calcification in right AV grove with pressure on right ventricle and right atrial, with no connection to cardiac chambers. Histopathological findings after complete resection of the mass revealed fibroconnective tissue with heavy calcification and no evidence of inflammation or malignancy. We reviewed the literature on pericardial solitary fibrous tumors up to 2020.

Solitary Fibrous tumor of the lumbar spine mimicking a sequestered disc fragment

Solitary fibrous tumor in the lumbar spine is a rare pathology with non-specific radiographic features, sometimes resulting in misdiagnosis. Our patient was a 41-year old female who presented with low back pain and bilateral leg pain. Initial MRI showed a lesion misdiagnosed for a sequestered disc at the mid L4-5 level, which was subsequently characterized appropriately and treated surgically, with resolution of symptoms. Pathologic diagnosis was most consistent with a solitary fibrous tumor due to STAT 6 and CD 34 reactivity. Long-term follow up is recommended in these patients to monitor tumor recurrence and evidence of metastasis.

Solitary fibrous tumor of bone developing lung metastases on long-term follow-up

Solitary fibrous tumors are rare mesenchymal neoplasms of fibroblastic or myofibroblastic origin. Primary solitary fibrous tumors arising in bone are extremely rare and rarely metastasize. We present a case of solitary fibrous tumor where the diagnosis was delayed due to a failure to recognize the subtle, lytic lesion underlying a fracture of the left humerus. The patient underwent proximal humeral replacement and was followed closely with imaging of humerus and chest. A small lung metastasis was found on CT scan 38 months later and was resected. Two additional small metastases were found and resected 62 months after initial tumor resection. The purpose of this case report is both to highlight the radiologic challenges which can lead to overlooking a lytic lesion underlying a fracture and to show the importance of long-term follow-up in patients with solitary fibrous tumor.

A dedifferentiated intracranial solitary fibrous tumor with osteosarcoma components: rapid tumor progression and lethal clinical course

Solitary fibrous tumor/hemangiopericytoma is a mesenchymal tumor that originates from a common NAB2-STAT6 fusion gene and is known to very rarely demonstrate dedifferentiation in the pattern of local recurrence or distant metastasis. Here we describe for the first time a rare case of intracranial dedifferentiated solitary fibrous tumor/hemangiopericytoma with osteosarcoma components that developed in an 84-year-old man after frequent gamma knife radiosurgery over a 14-year period. We performed tumor-debulking and gamma knife radiosurgery, but unfortunately the patient died shortly after the development of dedifferentiation. There is no established treatment for dedifferentiated cases due to the rare histology and limited published data, and therefore further accumulation of histological and genetic profiles is necessary to develop novel target gene therapies.

Cervical, Intradural Extramedullary Solitary Fibrous Tumor of the Spinal Cord: A Case Report and Review of the Literature

Solitary fibrous tumors (SFTs) are rare, spindle cell neoplasms of the mesenchymal origin. Lesions localized to the spine are exceptionally uncommon, only described in the literature in case reports and small case series. While these lesions are typically benign, there are a few reports in which they recur or present as malignancies. The patient presented in the case herein was a 72-year-old male, who presented with a 1-year history of lower extremity weakness, pain, and numbness and was found to have a cervical, intradural extramedullary tumor. In addition to the case report, the authors perform a thorough review of all previously published cases of spinal SFT.

Clinical and pathological analysis of solitary fibrous tumors with portal vein widening: A case report

RATIONALE

Solitary fibrous tumors (SFTs) are rare soft-tissue tumors characterized with spindle-cell, which occur more common in the chest and rarely seen in the abdomen. So far as we knew, SFTs accompanied with venopathy of portal vein has rarely been reported.

PATIENT CONCERNS

A 36-year-old male presented with left-sided abdominal mass and portal vein expansion on ultrasound.

DIAGNOSES

The post-operative histopathology confirmed the diagnosis of Solitary fibrous tumor.

INTERVENTIONS

Laparotomy was performed and the mass was completely removed.

OUTCOMES

Patients had no symptoms, recovered well without recurrence; the portal vein and splenic vein dilatation were alleviated and the symptoms of portal hypertension were relieved.

LESSONS

SFTs presents with few symptoms in the early stage of the disease. A rich arteriovenous shunt is beneficial to the diagnosis of SFTs by B-ultrasound and computed tomography (CT) examinations. However, the diagnosis of SFTs must depend on histopathology.

Malignant Solitary Fibrous Tumor of the Humerus: A Case Report of an Extremely Rare Primary Bone Tumor

Solitary fibrous tumor (SFT) is a spindle-shaped cell neoplasm originally described in the pleura, but subsequently found in many anatomic sites. Only few cases of primary SFTs in the bone have been previously described in the literature. We present the case of an 86-year-old man with a 1-week history of pain in his left arm. Imaging studies demonstrated a well-defined osteolytic lesion in the proximal humerus measuring 6.1 cm in diameter. Sections showed a round to spindle-shaped cell neoplasm with prominent mitotic activity (28 mitoses per 10 high-power fields) and areas of necrosis, focally surrounding staghorn-shaped vessels. The tumor cells were positive for CD34, CD99, Bcl-2, and STAT6 and negative for smooth muscle actin, epithelial membrane antigen, and cytokeratin AE1/AE3. These findings were consistent with a malignant SFT involving the left humerus. Although extremely rare, SFT should be considered in the differential diagnosis of primary bone tumors. This is the first case report of a primary SFT in a long bone with malignant histological features.

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.