Solitary fibrous tumors of the meninges: report of four cases and literature review.

We report four new cases of meningeal Solitary Fibrous Tumour (SFT). Two patients presented with raised intracranial pressure from posterior fossa SFT, and the third developed hemiparesis and dysphasia due to a large lesion that originated in the left middle cranial fossa. These were successfully excised and the patients remain well at follow-up of between 1 and 3 years. The fourth patient, a 71-year-old man, suffered an intracerebral haemorrhage and later died from a malignant SFT that had invaded the falx cerebri, superior sagittal sinus, and brain. This is the first description of a locally aggressive meningeal SFT with multiple atypical histological features. The 31 previously reported cases of meningeal SFT are reviewed. They occur at all ages and may be relatively more common in the posterior fossa and spine. Intracranial SFT originate from the dura and are probably indistinguishable from meningiomas on imaging and at surgery. In contrast, approximately two-thirds of spinal SFT have no dural attachment. Histologically, SFT are spindle-cell neoplasms with a characteristic immunohistochemical profile of CD34, vimentin, and bcl-2 positivity. Data on outcome for patients with meningeal SFT are limited. At other sites, however, extent of resection is the most important prognostic factor, and invasion or metastasis can occur with histologically benign SFT. Meningeal SFT should, therefore, be excised as completely as possible and followed carefully in the long-term.

Background:Solitary fibrous tumors (SFT) are uncommon mesenchymal neoplasms which can arise in any anatomical location. Pleural SFTs have been most frequently documented; however, breast SFT is an exceedingly rare entity and seldom present in male breast, with only 8 previously reported cases. Recently, STAT6 immunostaining was considered to be a definitive marker of SFT, however, no case of the male breast SFT showing STAT6 positivity preoperatively has been reported.Methods and Results:We describe a case of breast SFT in a 73-year-old male patient with a 12-month history of a palpable breast mass. The only associated clinical symptom was bilateral gynecomastia. An ultrasound scan examination revealed an oval, well-circumscribed and hypoechoic mass with hypervascularity. A core-needle biopsy was performed, and microscopic examination with immunohistochemistry confirmed the diagnosis of SFT. He underwent a complete surgical resection with clear margins, and there were no signs of high cellularity, remarkable mitotic activity, pleomorphism, hemorrhage or necrosis.Conclusion:A perioperative immunohistochemical evaluation for diffuse and intense nuclear expression of STAT6 was helpful to distinguish SFT from myofibroblastoma. We, herein, describe the first case of SFT in a male breast, confirmed by STAT6 immunostaining positivity. We also conducted a literature review of all previous cases of breast SFTs.

Solitary fibrous tumors (SFTs) are rare mesenchymal tumors that can occur at any location. Since the identification of specific NAB2-STAT6 fusion in SFTs, the fusion gene variants, NAB2 exon 4-STAT6 exon 2/3 and NAB2 exon 5/6/7-STAT6 exon 16/17/18, have been reported to be associated with clinicopathological features, and the latter variant is predominant in meningeal SFTs. SFTs developing in the salivary glands are rare, and more rarely, those involving ectopic salivary glands (ESGs) have been reported in the cerebellopontine angle (CPA); however, their characteristics remain not well understood. In this study, we performed a clinicopathological and molecular analysis of 3 cases of meningeal SFT with ESGs. All cases presented with an extra-axial mass in the CPA, which is a rarer location for intracranial ESGs compared to the sellar region. Histologically, except for the presence of ESGs, there was no significant difference between current cases and ordinary SFTs. The ESGs demonstrated no cellular atypia, and although the spindle tumor cells were immunopositive for STAT6, the ESGs were negative in all cases, supporting that the ESGs are non-neoplastic components. In 1 case, ESGs were found only in the primary tumor and disappeared in recurrence/dissemination. Of note, molecular analysis identified NAB2 exon 4-STAT6 exon 2 in all cases. In conclusion, our results suggest that ESGs particularly in the CPA may be associated with SFTs and that meningeal SFTs with ESGs may be associated with the minor fusion variant of NAB2-STAT6 in the intracranial lesions.

Solitary fibrous tumor involving the pancreas: report of the cytologic features and first report of a primary pancreatic solitary fibrous tumor diagnosed by fine-needle aspiration biopsy

OBJECTIVE AND IMPORTANCE: A solitary fibrous tumor (SFT) is a rare neoplasm of probable mesenchymal origin that was first reported in the pleura but can occur in different sites. Only six cases of SFT arising from the spinal cord have been reported. CLINICAL PRESENTATION: We report a case of primary SFT occurring in the thoracic spinal cord in a 64-year-old man with Brown-Séquard syndrome. Magnetic resonance imaging revealed an intradural mass at the level of T2–T3. INTERVENTION: Total T2–T3 laminectomies were performed. The tumor appeared to be adherent to the right lateral aspect of the cord but not attached to the meninges. On histological examination, the tumor exhibited spindle cell proliferation with abundant dense collagen but without a hemangiopericytomatous pattern. Immunohistochemically, the tumor cells were reactive with CD34 and vimentin only. CONCLUSION: We report a rare case of SFT occurring in the thoracic spinal cord. Histologically and immunohistochemically, we confirmed the diagnosis of SFT. Low signal intensity on T1- and T2-weighted images corresponded to the histological findings. When a spinal cord tumor exhibits a signal pattern similar to this, SFT should be included in the differential diagnosis. Because of the rarity of reports on this condition, the clinical manifestations and course of SFT of the spinal cord are unknown, and careful long-term follow-up is recommended.

Simple SummarySolitary fibrous tumors arising from the bone are an extremely rare event and only few cases have been previously described in the literature. It is characterized by a prominent, branched vascularization, with a thin and dilated vascular texture defined as “staghorn” and by the presence of the NAB2-STAT6 gene rearrangement, present in about 90% of cases and considered a pathognomonic feature. In the present study, we described our series of 24 cases of primary solitary fibrous tumor of the bone to find any clinical and molecular prognostic factors and to compare them with those currently used for soft tissue solitary fibrous tumor and to evaluate the risk stratification system proposed by Demicco, in order to understand whether this system was able to correctly predict the risk of local and distant metastatic relapse even in the case of solitary fibrous tumor of the bone.Primary solitary fibrous tumor (SFT) of the bone is extremely rare, with only few cases reported in the literature. We retrieved all cases of primary SFT of the bone treated at our institution and we assessed the morphology and the immunohistochemical and molecular features to investigate the clinical outcome of primary SFT of the bone and any clinical relevance of clinical and histological criteria of aggressiveness currently adopted for the soft tissues counterpart. Morphologically, 15 cases evidenced high cellularity, cytologic atypia, and foci of necrosis and were associated with more than 4 mitotic figures/10 HPF. Immunohistochemical analysis showed an expression of CD34 and of STAT6 immunopositivity in 95% and in 100% of cases, respectively. The presence of NAB2-STAT6 chimeric transcripts was found in 10 out of 12 cases in which RT-PCR analysis was feasible, whereas TERT promoter mutations analysis was feasible in 16 cases and only a C-to-T substitution in a heterozygous state was found in one DNA sample for the C228T genetic variant. P53 variants were assessed in 12 cases: 11 (91.6%) cases showed a variation, while in one case, no alteration was found. Disease-specific survival was 64% at 5 years and 49% at 10 years. Statistical analysis showed no correlation between survival and all the clinicopathological and molecular parameters evaluated. In conclusion, at difference to SFT of soft tissues, aggressive behavior of primary SFT of the bone seems to be independent from mitotic count or any other clinicopathological and molecular features.

A solitary fibrous tumor is a relatively uncommon neoplasm that usually occurs in the pleura but occurs extremely rarely in the oral cavity. Reported herein is a rare case of a solitary fibrous tumor in the buccal cheek mucosa. A 50-year-old man visited the authors' hospital due to a buccal cheek mass whose size had increased. Excisional biopsy was done under local anesthesia. After the excisional biopsy, the patient was diagnosed to have a solitary fibrous tumor. In immunohistochemistry, the patient's solitary fibrous tumor was characterized by the expression of CD34 and CD99 on the neoplastic cells, and negativity for Bcl-2 and S-100. No recurrence or complication occurred for a period of 5 years. The growth of a primary solitary fibrous tumor in the buccal cheek mucosa is extremely rare and has been rarely reported in the South Korean medical literature. A solitary fibrous tumor must be distinguished from other spindle cell tumors. Presented herein is a case of primary solitary fibrous tumor in the buccal cheek mucosa. The relevant literature is briefly reviewed.

Multiple Recurrent Malignant Solitary Fibrous Tumors: Long-Term Follow-Up of 24 Years

Solitary fibrous tumor (SFT) is an extremely rare tumor of the pancreas. The content of stromal tissue in the pancreas is insignificant, this fact explains the extremely rare occurrence of mesenchymal tumors (less than 1% of pancreatic neoplasms). It has been described only 16 such cases in the world literature.A clinical case of solitary fibrous tumor of the pancreatic head of a man 43 years old, illustrating the difficulty of diagnosis is presents in the article/ In order to emphasize difficulties in diagnostics we introduce you another clinical case of extrapleural solitary fibrous tumors of the retroperitoneal space of a woman 63 years old.Pancreatic SFT and NEN cannot be reliably differentiated on the basis of lesion structure and contrast medium uptake. However, in most cases SFT will progradiently enhance due to abundant collagen stroma, leading to marked difference between delayed-phase images of SFT and NEN with cystic degeneration. SFT is a rare tumour and radiologist should be aware of its characteristics, particularly in the setting of NEN with cystic degeneration or atypical contrast uptake.

Purpose: A Solitary fibrous tumor is a rare orbital neoplasm derived from mesenchymal cells. The neoplasm should be considered in differential diagnosis of any orbital tumor, and immunohistochemial analysis is important for correct diagnosis. The authors herein describe a case of a solitary fibrous tumor in addition to the findings of a literature review. Solitary fibrous tumors can develop from not only the lacrimal gland, but also orbital soft tissue. Until now, there has been no report of a solitary fibrous tumor arising from orbital soft tissue in Korea. Case summary: A 50-year-old man visited our clinic due to a slow progressing mass on the lateral side of the left eye for 1 year. The patient did not suffer from any discomfort or discharge from the mass. Slit lamp and other ocular examinations were unremarkable. Orbital MRI revealed a solid extra-conal enhanced mass that measured 1311 mm adhering to the lateral wall of the left orbit. Total surgical excision was Performed under local anesthesia and tumor cells showed a strong and diffuse positivity for CD34 by immunohistochemistry. The findings were consistent with the diagnosis of orbital solitary tumor. Conclusions: The orbital solitary tumor is rare, but it should be considered in the differential diagnosis of any orbital tumor.

Solitary fibrous tumor is an extremely rare clinical entity, most commonly manifested in the pleura and peritoneum. An increasing number of cases are found to occur at extrapleural sites. We report a case of solitary fibrous tumor arising from the mesentery of the small intestine. A 53-year-old man presented with a large abdominal mass which was initially thought to be a gastrointestinal stromal tumor. The tumor was successfully removed surgically and the diagnosis of solitary fibrous tumor was confirmed on immunohistochemical analysis. To our knowledge this is the first reported case of a solitary fibrous tumor arising from the small bowel mesentery.

Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms, displaying variable morphological and clinicopathological features. Supportive immunohistochemical markers such as CD34, CD99, BCL2 and LSD1 are commonly applied in the differential diagnosis of SFTs, although none is sufficiently sensitive or specific enough. The aim of the present study was to examine the most differential markers for the reliable distinction of SFTs from histological mimics. We investigated the expression of STAT6, NAB2, ALDH1, GRIA2 and IGF2 in 454 comprehensive soft tissue tumors, comprising formalin-fixed paraffin-embedded (FFPE) tissue samples from 80 SFTs and 374 other mesenchymal tumors. The Duolink in situ proximity ligation assay (PLA) was adopted for the detection of NAB2-STAT6 fusion proteins. STAT6 was expressed in all 80 SFT cases with a moderate-strong nuclear staining intensity. In contrast, only 4/374 (1%) non-SFT mesenchymal tumors showed a nuclear STAT6 staining pattern. Strong expression of NAB2 and IGF2 was detected in SFT and non-SFT cases. Positive GRIA2 immunoreactivity was found in 64% (SFT) and 8% (non-SFT), respectively. Expression of ALDH1 was moderate-strong in 76% (SFT), whereas only 2 non-SFT lesions showed positive ALDH1 immunoreactivity. Moreover, the presence of NAB2‑STAT6 fusion proteins was indicated in 71/78 (91%) SFT cases by PLA. Nuclear STAT6 and cytoplasmic ALDH1 expression are the most sensitive and specific markers in the differential diagnosis of SFTs. Furthermore, application of Duolink in situ proximity ligation assay can be helpful to detect the NAB2-STAT6 fusion protein in the majority of SFTs.

Orbital solitary fibrous tumor (SFT) is an extremely rare variant of systemic SFTs. However, the relationship between the biological/clinical characteristics, histological malignancies, and known oncogenes of systemic SFTs has not yet been elucidated. Therefore, we investigated these features and explored the prognostic factors of orbital SFTs by analyzing a series of orbital SFT cases. Six orbital SFT and one meningeal SFT were analyzed for comparison. NAB2::STAT6 variants were identified in five of the six orbital SFTs cases and one meningeal SFT case. There was no correlation between the exon composition of NAB2::STAT6 variants and the time of relapse after surgery or histological malignancy. Nuclear STAT6 staining by immunohistochemistry was observed in all cases, whereas cytosolic STAT6 staining was confirmed in three orbital SFT cases. The presence of histological malignancies and positive cytosolic STAT6 staining were mutually exclusive. The diffuse strong expressions of p53 and p16 were confirmed only in a case with the worst clinical course. No TERT promoter mutations were observed in any of these cases. Our study suggests that positivity of cytosolic STAT6 staining and high p53/p16 expression may be a predictor of histological/clinical malignancy in orbital SFT. Further evidence is necessary to confirm our results.

We aimed to report a case of orbital solitary fibrous tumour (SFT) in a child and to review the relevant literature. We describe an SFT in a 13-year-old boy with a 1-month history of painless proptosis in the left eye. Magnetic resonance imaging revealed a well circumscribed mass filling most of the left intraconal orbit. The lesion was excised and histopathological examination revealed a malignant SFT. Postoperative follow-up for 18 months was uneventful. Malignant SFT of the orbit should be included in the differential diagnosis of paediatric orbital tumours. Complete surgical excision remains the preferred method of management and the longterm prognosis is guarded.

This paper reports a rare case of solitary fibrous tumor(SFT) arising independently from the external auditory canal. A 16-year-old female patient presented with mass in left external auditory canal and aural fullness. Physical examination revealed a large papillomatous mass coming out from left external auditory canal. The patient underwent surgical removal of tumor. A light microscopic study showed a spindle-cell proliferation with a collagenous stroma and a staghorn-like vascular pattern. The tumor cells were immune histochemically positive for vimentin. One week after resection aural fullness had resolved. Solitary fibrous tumor is a rare mesenchymal tumor which originates in the pleura or at virtually any site in the soft tissue.It has been observed that 78% to 88% of SFT's are benign and 12% to 22% are malignant.En-bloc resection remains the cornerstone of therapy. Although, several cases of extra pleural SFT have been reported, only one case of external auditory canal SFT has been reported so far. Excision of SFT of the external auditory canal is advisable, especially in the presence of symptoms, and should be preceded by confirmation of non-malignancy by biopsy, if possible.