Malignant Transformation of a Solitary Fibrous Tumor with Intracranial Invasion and Distant Metastasis: A Case Report

The solitary fibrous tumor (SFT) is a very rare and usually benign neoplasm. This tumor is mostly located in the thoracic cavity, but it has also been reported in numerous sites including liver, skin, and meninges. Due to its rarity diagnosis is often difficult. Accordingly, histopathological differentiation is of major importance. Solitary fibrous tumors consistently express CD 34 and react negatively to epithelial markers. This absence of expression of epithelial markers, especially cytokeratin, is also useful to distinguish these rare entities from sarcomatous mesotheliomas. The treatment of choice for solitary fibrous tumors is extensive surgical resection. Up to now there is no evidence that radiation and chemotherapy are effective. The local recurrence or onset of metastases depends on histologic parameters. In cases of benign classification (60-80%), the recurrence rate was only 2% after surgical excision. One-half of the patients with malignant tumors can be cured; the rest develop recurrences and metastases more often. Especially in those cases, emphasis should be placed on continual follow-up examination. We report two cases of a 65- and a 75-year-old male patient with huge intrathoracic solitary fibrous subpleural tumors, discovered incidentally on routine chest X-ray.

Background: In the WHO 2016 classification of central nervous system tumors, solitary fibrous tumors (SFT) and hemangiopericytomas (HPC) were considered part of the same category given a shared mutation. Nevertheless, since the new 2021 WHO classification, the term “hemangiopericytoma” has been retired, and SFT is considered an independent pathological entity.Methods: We reviewed the literature following preferred reporting items for systematic reviews and meta-analyses guidelines focusing on the treatment options and prognosis of patients with cervical SFT. We also present a 68-year-old female with spinal intradural extramedullary SFT complicated by diffuse extension into paravertebral tissues and muscles.Results: We found 38 cervical SFT in the literature. Patients averaged 47.3 years of age and 47.4% were female. Typically, these lesions spanned two spinal levels resulting in cord compression and most frequently exhibited benign features (i.e., diagnosed as Grade I SFTs). Interestingly, two patients exhibited distant metastases and had initial pathology consistent with grade II SFT.Conclusion: SFT of the cervical spine is rare and its management varies according to the histological grade and the clinical behavior, generally warranting surgical excision and adjuvant radiation therapy and/or systemic chemotherapy.

BackgroundA solitary fibrous tumor (SFT) is a rare mesenchymal tumor that occurs mostly in pleural sites, and an SFT occurring in the ischiorectal fossa is extremely rare. Because of the rarity, there are few reports detailing an SFT in the ischiorectal fossa.Case presentationA pararectal tumor was incidentally found in a 42-year-old man during a routine medical examination. The patient had no symptoms and no previous medical history. In the physical examination, a smooth-margined and hard elastic mass was felt, and in a digital rectal examination, the rectal mucosa appeared normal. A computed tomography (CT) scan showed a 5-cm, well-defined, solid mass in the left ischiorectal fossa. Contrast-enhanced CT in the early phase showed intense heterogeneous enhancement that persisted during the delayed phase. T2-weighted images of magnetic resonance imaging yielded heterogeneous intermediate and low signal intensity. Intense arterial enhancement suggested a hypervascular nature, and persistent delayed enhancement and low signal bands on T2-weighted images suggested a fibrous component of the mass. An SFT was suspected. Most SFTs are benign but have malignant potential. Our patient did not hope for surgery if the tumor was benign; therefore, an ultrasound-guided transperineal core needle biopsy was performed to decide on a treatment strategy. Microscopic examination showed tumor cells appearing as spindle and fibroblast-like cells within a collagenous stroma. Immunohistochemistry identified CD34 and vimentin, supporting the diagnosis of an SFT. The patient consented to excision of the mass. He was placed in a prone jackknife position, and the tumor was removed transperineally using a posterior approach (modified Kraske procedure). The levator ani muscle, external sphincter muscles, and rectum were not involved and separated from the tumor. The tumor was successfully resected en bloc with no complications. Five uneventful days post surgery, the patient was discharged. There was no local recurrence during the year following surgery.ConclusionImaging findings reflect the tissue characterization such as hypervascularity and fibrous nature of SFTs. We have presented a rare case of an SFT in the ischiorectal fossa with useful imaging findings for diagnosis, treatment strategy, and successful surgical removal using a posterior approach.

Solitary fibrous tumors are rare mesenchymal tumors that typically occur in the pleura. Solitary fibrous tumors of the uterine cervix are uncommon. We report the first case of a patient who underwent total hysterectomy for vaginal wall adenocarcinoma and was found to have a concurrent solitary fibrous tumor in the paracervical-uterus. A 51-year-old woman was admitted to our hospital due to contact bleeding. A gynecological examination revealed nodules of 3.0 × 1.0 cm on the vaginal wall, and a colposcopy with biopsy revealed adenocarcinoma of the vaginal wall. After the recommended staging examinations, the patient underwent total hysterectomy, double adnexectomy, pelvic lymph node dissection, and vaginal wall resection. During surgery, a nodule measuring approximately 2 × 2 cm was found in the middle of the mass in the left paracervical region. Subsequent postoperative histopathological examination confirmed an solitary fibrous tumor of the uterine cervix with adenocarcinoma of the vaginal wall. The patient was followed up for 46 months after hospitalization, and no recurrence or distant metastases were observed. In rare cases, solitary fibrous tumors may form large masses in the cervical or vaginal wall. They can easily be misdiagnosed as benign or malignant cervical tumors before and during surgery. Postoperative pathology and immunohistochemistry are helpful for diagnosis. Most solitary fibrous cervical tumors are benign, occasionally with low malignant potential, and surgical treatment is feasible and effective.

Rationale:Solitary fibrous tumors of central nervous system are rare spindle-cell mesenchymal tumors. Although most are benign in nature, malignant transformation and extracranial metastasis have been reported. Up to now, only one case of CSF dissemination was described. Here we described an extremely rare case of intracranial Solitary fibrous tumors arising from the pineal region with a delayed ectopic metastasis.Patient concerns:A 35-year-old female presented with double vision, memory disturbance and unsteady gait was referred to our center. MRI showed an irregular mass in the pineal region.Diagnoses:The patient was diagnosed as pineal tumor, with unknown pathology.Interventions:Gross total resection was achieved and the pathologic studies confirmed a solitary fibrous tumor. Thirty-nine months later local recurrence occurred and gamma-knife radiotherapy was offered. Seven months later, MRI found a metastasis in the left temporal lobe. Surgical resection was conducted and pathological analysis revealed changes in cell morphology, counts and Ki-67 level, confirmed the diagnosis of solitary fibrous tumor/hemangiopericytoma (WHO Grade III). The patient received post-operational radiotherapy.Outcomes:The patient was followed up for 7 months with no signs of recurrence.Lessons:Here, we report an extremely rare case of primary solitary fibrous tumor of pineal region with delayed intracranial ectopic metastasis, together with literature review of metastatic solitary fibrous tumors. Strict surveillance is strongly recommended, considering the malignant potential of this seemingly benign disease entity. Complete resection of the tumor is the treatment of first choice and radiotherapy might be an effective adjuvant therapy for high grade SFT/HPCs.

Solitary fibrous tumors (SFTs) are rare mesenchymal pleural neoplasms with an overall good prognosis and low recurrence rate if completely resected and if degree of differentiation is favorable. Within the last decade, advances in research have led to more reliable methods of differentiating SFTs from other soft tissue tumors. Historically, several markers were used to distinguish SFTs from similar tumors, but these markers had poor specificity. Recent evidence showed NAB2-STAT6 fusion gene to be a distinct feature of SFTs with 100% specificity and sensitivity. Surgical resection, with an emphasis on obtaining negative margins, is the mainstay of treatment for SFTs. Preoperative planning with detailed imaging is imperative to delineate the extent of disease and vascular supply. One important radiologic distinction to aid delineation of a pleural-based tumor compared to a pulmonary parenchymal-based tumor is the angle that the tumor forms with the chest wall, which is obtuse for a pleural-based tumor, and acute for tumors of the lung parenchyma. Often, preoperative tissue diagnosis is not available, and surgery is both diagnostic and curative. Intraoperatively, emphasis should be on complete resection with negative margins. SFTs are resected via several approaches: thoracotomy, sternotomy with the option of hemi-clamshell extension, video-assisted thoracoscopic surgery, and robotic approach, which is increasingly being used and is our preference. We recommend a minimally invasive approach for most lesions, and have resected SFTs of the pleura that are up to 12 cm with the robotic approach. However, the current literature often cites 5 cm as the cut off for an open thoracotomy. Nevertheless, even with larger tumors, a minimally invasive robotic approach is our preference and practice. For giant SFTs (> 20 cm), an open approach may be preferable. Multiple thoracotomies and rib resection may be required to gain adequate exposure and ensure complete resection in these tumors. However, it is noteworthy that most of these tumors have a soft consistency and thus, once bagged, can easily be removed minimally invasively, and thus minimally invasive approach should not be completely ruled out. Recurrence in SFTs usually results from incomplete resection and redo surgery may portend a favorable prognosis.

We present a retrospective study of 65 cases of solitary fibrous tumors (SFTs) of several localizations including the most common site of origin in the pleura and lungs. SFTs are mesenchymal fibroblastic tumors with an unpredictable biological potential ranging from benign to malignant. We investigated morphologic characteristics, proliferation activity evaluated by immunohistochemical expression of Ki-67 antigen, and the existence of NAB2-STAT6 fusion gene together with Ki-67, TPX2, and TERT mRNA expression levels. The aim was to define relationships between proliferation activity and biological potential and progression of the disease. We measured Ki-67, TPX2, and TERT mRNA levels using quantitative real-time reverse transcription PCR (RQ-RT-PCR). We observed a significant association between increased Ki-67 and TERT mRNA levels and the SFTs with malignant potential. Also, we investigated the effect of TERT promoter mutation on telomerase activation and patient outcome in our SFT cohort. We verified that TERT promoter mutation was frequent (36.6%) and present in a majority of malignant SFTs and SFTs with uncertain biological behavior. TERT promoter mutation alone predicted the disease recurrence.

Solitary fibrous tumor (SFT) of the pleura is a rare mesenchymal neoplasm arising from mesenchymal cells in the areolar tissue subjacent to the mesothelial-lined pleura and accounting for less than 5% of primary pleural tumors. SFTs are generally benign and asymptomatic, with 10-year survival rates of up to 98%. Unfortunately, approximately 10% have malignant potential, leading to local recurrence after radical surgery and/or metastatic spread. Of note, giant pleural SFT, which consists of a tumor occupying at least 40% of the affected hemithorax, is even less common with only anecdotal cases reported in the medical literature. We describe a unique case of giant SFT of the pleura that metastasized to the thyroid gland 1 year after complete resection, focusing on its clinical and pathological features of presentation. En bloc resection remains the mainstay of therapy with curative intent. Patients with large tumors may undergo preoperative angiography with percutaneous embolization of the tumor, which allows to reduce perioperative bleeding. In case of local recurrence, surgery still remains the best treatment option. However, surgery can also be considered in patients with isolated metastatic spread. Every suspected and proven SFT of the pleura should undergo surgical resection, as clinical and radiological criteria cannot accurately distinguish benign from malignant forms. Moreover, the peculiar histological features of SFT should not be neglected when planning clinicoradiological follow-up. Additionally, suspicious clinical findings during follow-up should always be thoroughly investigated in order to exclude or confirm the diagnosis of recurrent disease.

A solitary fibrous tumor is a relatively unusual neoplasm first described as a distinctive tumor arising from pleura. Some reports have shown that solitary fibrous tumors also affect extrathoracic regions. The current study presents a literature review with four additional patients with solitary fibrous tumor arising from the extremities to clarify clinicopathologic features. The current four patients were two males and two females, ranging from 17 to 60 years of age. Magnetic resonance imaging scans of the current patients showed inhomogeneous low to intermediate intensity signal on T1-weighted images and inhomogeneous intermediate to high intensity signal on T2-weighted images. Histologically, the tumors were composed of a haphazard proliferation of spindle cells, although cellularity was variable in each case. Two of the four tumors showed hypercellularity of spindle cells with focally myxomatous or hyaline changes, whereas myxomatous patterns with scattered spindle cells throughout the specimens were observed in the other two tumors. Immunohistochemically, all four patients showed positive immunoreactivity for CD34, and two tumors showed focally positive immunoreactivity for bcl-2 protein. During the followup of 12 to 54 months, neither local recurrence nor distant metastasis was detected after wide resection. Examination of the literature and the current patients suggests that solitary fibrous tumors in the extremities are likely to have a malignant potential, although most patients have a benign clinical course. Local wide resection and careful long-term followup are necessary for patients with solitary fibrous tumor in the extremities.

Purpose: The diagnoses of solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) have evolved over the past decades. Due to histopathological similarities, they were grouped as the same entity highlighting the complexity of this rare condition. Previous studies suggest that orbital HPC-pattern tumors are more aggressive than SFTs. We analyzed the histopathological and immunohistochemical features of patients with orbital SFT/HPC to further classify this entity. Materials and Methods: We reviewed eight orbital SFT/HPC cases from McGill University Health Centre (2011–2019). All of them were diagnosed as SFT, three with HPC pattern. Vascular proliferation (HPC) and spindle cell morphology (SFT) were evaluated. The tumors were stained with STAT6, CD34, Ki67, SMA, EMA, and S100 protein and further analyzed. Results: The average age was 49 years, and seven were male. Follow-up ranged from 6 to 96 months. Three patients (two males and one female) had an HPC pattern (average age of 54 years). Five male patients had only SFT pattern (average age of 46 years). In HPC cases, STAT6 was negative, CD34 and SMA were positive, S100 protein and EMA were negative, and Ki67 was low (5%–10%). In SFT cases, STAT6 and SMA were positive, CD34 was positive (in spindle cells and vessels for two cases, vessels only in three), S100 protein and EMA were negative, and Ki67 was low (5%–20%). Conclusion: These results highlight the pathological variability of orbital SFT/HPC. Immunohistochemical profiling helps differentiate between SFT and SFT with HPC pattern, which is essential, as HPC have a higher risk of recurrence and malignant transformation.

We present a rare combination of a solitary fibrous orbital tumor and uterine cancer in a female patient with type I neurofibromatosis. This 77-year old patient developed a left painless exophthalmos within 2 years and decreased visual acuity of the left eye. At the age of 20 she was diagnosed with type I neurofibromatosis. Half a year ago she underwent hysteron-oophorectomy due to uterine adenocarcinoma. The visual acuity of her left eye was decreased to 0.3, with an increase of intraocular pressure to 30 mm Hg. She had a 13-mm left-sided exophthalmos with misplacement of the eye downwards and laterally at 40°. Reposition of the left eye was severely impaired, with limitation of the eye movements to all directions. Ophthalmoscopy showed optic disc discoloration and blunting of its inner border. The patient underwent trans-conjunctival orbitotomy, with removal of three encapsulated tumor nodules. Histological and immunochemical studies of the removed tissue identified solitary fibrous tumor of the left orbit with an undetermined malignant potential. In the post-operative period, visual acuity of the left eye was 0.2, with no exophthalmos and right position of the eye. There was a non-significant limitation of the left eye movement to the left and to the right. X-ray computed tomography confirmed radical tumor excision. Conclusion: Solitary fibrous tumor is a rare orbital neoplasm. Nevertheless, it should be included into the differential diagnosis list of spin-cell orbital tumors. It is necessary to aim at tumor removal through the least traumatic orbital access. Relapsing course of the tumor is the rationale for a long-term follow-up of patients after removal of solitary fibrous orbital tumor.

A solitary fibrous liver tumor is a rare disease that is difficult to diagnose. Radiological findings are not specific and cannot confirm benignity or malignancy. Immunohistologically, CD 34, Vimentin, and Desmin should be used as markers to precisely diagnose solitary fibrous tumors. In most cases, there is low cellularity with no cellular atypia or necrosis, making this a benign lesion. Occasionally, a large size, high mitotic rate, cellular pleomorphism and atypia, and necrosis are interpreted as features suggestive of an increase malignant potential. The outcome of solitary fibrous tumor mostly is related to resectability, although correlated with neither pathological grade nor tumor size. Thus, total surgical resection of the neoplasm is most commonly proposed. Physicians should be alerted that solitary fibrous tumor of the liver can be malignant and can metastasize.

Solitary fibrous tumor and desmoplastic small round cell tumor are primary peritoneal malignant tumors. Despite their morphological differences, these diseases are united by low morbidity, the lack of pathogenic symptoms, similar radiological signs, and scant knowledge of prognostic factors. Considering the low morbidity, reliable differential diagnostic signs have not been established at present, which greatly complicates the timely formulation of the diagnosis. On the contrary, cases of choosing the wrong treatment tactics and the lack of a unified management algorithm are increasingly being identified. Radiation and instrumental diagnostic methods such as computed tomography, magnetic resonance imaging, laparoscopy are crucial in determining the extent of the tumor, it is necessary to take into account the biological characteristics of the tumor (morphological type), which affect the nature of tumor growth. With a solitary fibrous tumor and a desmoplastic small-round cell tumor, the computed tomography picture is characterized by the presence of isolated nodular formations in any part of the abdominal cavity, which can also be accompanied by a large omentum, ascites, an increase in retroperitoneal lymph nodes, and distant metastasis to the lungs and bones is possible. In general, the main task of diagnosing a primary peritoneal neoplasm is to take sufficient quality biological material, with the leading role in the diagnosis being given to histological and immunohistochemical studies. On the other hand, the independent experience of many clinics does not exceed single surveillance. This information does not allow doctors to confidently navigate the problem; accordingly, there is a need for multicenter and, possibly, prospective, randomized scientific research in order to develop a unified algorithm for managing patients with primary peritoneal tumors. The approaches to the treatment of these tumors are currently not standardized and not well studied due to the rarity of the pathology. According to the available information, the treatment of desmoplastic small round cell tumors is based on multimodal therapy, including systemic chemotherapy and surgery, and possibly radiation therapy. Traditional treatment algorithms for this pathology include the surgical stage and systemic or intracavitary chemotherapy, while the treatment sequence may be different and depends primarily on the prevalence of the disease. For solitary fibrous tumor, surgical treatment, by contrast, is the method of choice. Thus, when choosing a treatment strategy for a primary peritoneal tumor, it is first of all necessary to take into account the morphological type of the tumor and rely on known data on the benefits of a particular method. In this article, we tried to present modern information on the diagnosis and treatment of rare forms of primary peritoneal tumors.

Unusual Solitary Fibrous Tumors in the Central Nervous System: A Report of Two Cases

Primary omental malignant solitary fibrous tumour, an extremely rare malignancy: A case report and review of the literature