Majority Of Solitary Fibrous Tumors Research Articles

A Giant Solitary Fibrous Tumor of the Liver with Metastasis and Local Recurrence

Solitary fibrous tumor (SFT) is a rare type of mesenchymal neoplasm. Although the majority of SFTs are benign, some cases have shown characteristics of malignant neoplasms. Weight loss, fatigue, and upper abdominal bloating are the main signs of these lesions. Clinical and radiographic features are not sufficient for the diagnosis of hepatic SFT and the definitive diagnosis depends on histopathological sampling and immunohistochemistry. One of the main issues in the diagnosis of this tumour is the ability of this tumour to grow to large sizes. A 69-year-old male presented to the clinic 2 years earlier with episodes of hypoglycemia and loss of consciousness. The symptoms improved after receiving glucose. The patient diagnosed as rare solitary fibrous tumour of the liver, a giant (10 × 10 cm in diameter) round and well-defined lesion in the left lobe of the liver which was obvious in magnetic resonance imaging (MRI). Surgery is the most common line of treatment for this disease and there is no evidence regarding the effectiveness of other approaches. According to the scarcity of hepatic SFT, long-term prognosis in these patients is highly challenging. Here, we present the case of a 69-year-old male patient with hepatic SFT with metastasis and local recurrence. In the very rare malignant form of liver solitary fibrous tumour which is surgically unresectable, liver transplantation is one of the potential options but maybe not amenable due to the malignant behaviour of the disease. Role of debulking surgery is also not clear in this situation.

1642P - Determination of biological behavior of solitary fibrous tumors

Background: Solitary fibrous tumor (SFT) is an uncommon neoplasm of pleural and extrapleural site of origin formed by cells with fibroblastic features. This tumor exhibits a spectrum of biological behavior and can occur at any age with the peak in the sixth and seventh decade of life. Most of these tumors grow slowly and their clinical behavior is mostly benign; however, up to 20 % of patients develop local recurrences and/or distant metastases. Methods: We performed a retrospective study of 54 cases of SFTs. We investigated morphologic characteristics, proliferation activity evaluated using Ki-67 immunostain and existence of NAB2-STAT6 fusion gene together with Ki-67, TPX2, and hTERT mRNA expression levels. The aim was to define relationships between proliferation activity and biological potential and progression of the disease. Recently, several alterations within the TERT gene have been detected in human tumors. The most frequent alteration in the TERT gene, somatic promoter mutation, has been described. We measured Ki-67, TPX2, and hTERT mRNA levels using quantitative real-time reverse transcription PCR (RQ-RT-PCR). Determination of hot spot promoter mutation in TERT was analyzed. Results: NAB2-STAT6 fusion transcript was found in 46/54 cases (85%) of amplifiable samples. The mRNA expression of Ki-67 correlated with local recurrences (p = 0.025) and biological behavior of the tumor (p = 0.0027), but did not correlate with the type of the NAB2/STAT6 fusion (0.24). The level of Ki-67 mRNA correlated with IHC established results (p = 0.02). The TPX2 mRNA expression did not correlate with local recurrences (p = 0.26) nor with biological behavior of the tumor (p = 0.062). The mRNA hTERT expression correlated well with biological behavior of the tumor (p < 0.0001). The majority of SFTs with benign behavior were without detectable expression of hTERT mRNA. A majority of the patients with hTERT expression had also somatic promoter mutation C228T or less frequently C250T. We observed a significant association between increased Ki-67 and hTERT mRNA levels and the SFTs with malignant potential. Conclusions: Detection of hTERT mRNA expression and its promoter mutation at routine practice might lead to a better estimation of a biological potential of SFTs. Legal entity responsible for the study: Ministry of Health, Czech Republic. Funding: Supported by the Project (Ministry of Health, Czech Republic) for conceptual development of research organization 00064203 (University Hospital Motol, Prague, Czech Republic). Disclosure: All authors have declared no conflicts of interest.

Prognostic value of MIB-1 proliferation index in solitary fibrous tumors of the pleura implemented in a new score \u2013 a multicenter study

BackgroundAlthough the majority of solitary fibrous tumors of the pleura (SFTP) follow a benign course, 10–25% of patients suffer from recurrence or metastatic disease. Several scoring models have been proposed to predict the outcome. However, none of these included immunohistochemical (IHC) markers as possible prognosticators.MethodsIn this multicenter study, we collected clinical data and formalin-fixed and paraffin-embedded (FFPE) tissue blocks of patients with histologically proven SFTP which had been surgically resected between 2000 und 2015. After systematic and extensive IHC staining on tissue microarrays, the results were analyzed and compared to histomorphological and clinical data for their possible prognostic value.ResultsIn total, 78 patients (mean age 61 ± 11 years) were included. Of these, 9 patients (11%) had an adverse outcome including SFTP recurrence (n = 6) or SFTP-related death (n = 3). Mean overall survival was 172 ± 13 months. 1 and 10-year event-free survival rates were 99% and 93%. In the multivariable analysis only MIB-1 proliferation index (Ki-67) ≥10% (HR 12.3, CI 1.1–139.5, p = 0.043), ≥4 mitoses per 10 high power fields (HR 36.5, CI 1.2–1103.7, p = 0.039) and tumor size larger than 10 cm (HR 81.8, CI 1.7–4016.8, p = 0.027) were independently associated with adverse outcome.ConclusionA high proliferation rate by MIB-1 IHC was associated with impaired outcome. Upon this, we established a new score using mitosis, necrosis, size of the tumor and MIB-1, which performed better than the traditional scores in our data set. This prognostic score could help to better evaluate outcome of SFTP, but requires external validation.

A Case of Wandering Malignant Solitary Fibrous Tumor

Introduction: Solitary fibrous tumor (SFT) is a rare mesenchymal tumor of fibroblastic origin, which may originate from any part of body but most commonly arises from the visceral pleura. We present a rare case of wandering malignant SFT, arising from the lesser omentum. Case: A 60 year old Caucasian male with history of hypertension and diabetes mellitus, admitted initially, for fall in nursing home, developed nausea, vomiting and abdominal distension. A palpable mass was noted on abdominal examination. Non-contrast CT revealed a 17 cm pedunculated bilobed mass with eccentric calcifications in right mid abdomen compressing pylorus with a markedly distended stomach and gastric wall pneumatosis. Repeat CT abdomen with contrast in 12 hours showed interval migration of the mass into the left abdomen with twisting of the mesenteric root and narrowing of the venous structures. The patient underwent emergent exploratory laparotomy with resection of a 1.5 kg mass. Biopsy revealed spindle cell proliferation and abundant collagenous stroma along with large necrotic areas and increased mitotic activity. Immunohistochemical stains were positive for CD34 and STAT6 consistent with malignant SFT. Patient had an uneventful postoperative course and repeat CT imaging after 3 months confirmed complete resolution. Discussion: SFTs are mesenchymal tumors commonly arising from pleura but extrathoracic SFTs have been reported such as intra-abdominal originating from omentum as in our case. Majority of SFTs are benign while 12-22% are malignant. Mean age of onset is 55-65 years. These may be associated with paraneoplastic syndromes, most commonly hypoglycemia or hypertrophic pulmonary osteoarthropathy. Differential diagnoses include gastrointestinal stromal tumor, neurogenic tumors, myogenic tumors or vascular tumors. CD 34 and STAT6 are useful positive biomarkers for SFT as in our case. Molecular hallmark in SFT is recurrent gene fusion of NAB2-STAT6 on chromosome 12q13-15. Imaging modalities including CT or MRI can be suggestive of the diagnosis but definitive diagnosis requires a tissue specimen. The mainstay of treatment is complete surgical resection with clear margins. They can have unpredictable biological behavior and can recur locally or disseminate. Long-term surveillance is recommended post operatively, as disseminated recurrence can occur in tumors with histological features of malignancy, but data to guide further management of such patients is lacking.Figure 1Figure 2

Differential diagnosis of solitary fibrous tumors: A study of 454 soft tissue tumors indicating the diagnostic value of nuclear STAT6 relocation and ALDH1 expression combined with in situ proximity ligation assay.

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.

NAB2–STAT6 Fusions Are a Hallmark of Solitary Fibrous Tumors

NAB2-STAT6 gene fusions occur in the vast majority of solitary fibrous tumors.

Suboccipital Malignant Solitary Fibrous Tumor: Report of a Case

Solitary fibrous tumors (SFTs) are rare soft-tissue sarcomas usually arising in the pleura of the thoracic cavity. Thirty percent of SFTs present in extrapleural locations, and infrequently in the head and neck region. While the majority of SFTs are benign, aggressive variants have been described. We report a case of a patient with a malignant SFT arising in the suboccipital soft tissues of the neck. We elucidate the diagnostic and therapeutic challenges in managing this tumor in this unusual location.

Solitary fibrous tumor. A cytologic-histologic study with clinical, radiologic, and immunohistochemical correlations.

Solitary fibrous tumors (SFT) are rare neoplasms that most commonly involve the pleura, mediastinum, and lung. They are believed to be submesothelial in origin. Histologically, they are characterized by fibroblast-like cells and connective tissue in varying proportions. The "patternless pattern" and the hemangiopericytoma-like pattern are the most common arrangements. The majority of SFTs have been immunoreactive for CD34. Very little has been reported regarding the cytologic findings in these tumors. The authors reviewed the radiographic findings and studied fine-needle aspiration biopsies performed on seven patients with SFT of the pleura, and examined subsequent histologic material. The cell blocks or smears of all cases were stained with a monoclonal antibody to CD34. The cytologic preparations showed varying degrees of cellularity. Smears were comprised of spindled cells in a bloody background with small amounts of collagen. The three malignant tumors had a greater number of cells, both dispersed and in clusters, with nuclear pleomorphism and prominent nucleoli. The cell blocks characteristically showed varying degrees of cellularity with thickened blood vessels and a hemangiopericytoma-like pattern. The cells from the four benign tumors tended to be smaller in size and grouped in more cohesive clusters than the malignant ones. CD34 stained the spindle tumor cells in the cell blocks or smears from five cases; one malignant and one benign case failed to stain. The corresponding histologic samples from these cases demonstrated the same CD34 staining pattern in all cases except one. The differential diagnosis of SFT includes neurogenic tumors, mesotheliomas, sarcomatoid carcinoma, synovial sarcoma, hemangiopericytoma, and fibrosarcoma. CD34, when present, may prove equally helpful as a positive marker in cytology and in histologic preparations in the differential diagnosis of SFT.