Solitary fibrous tumors (SFTs) are a rare type of mesenchymal lesion in which specific clinicopathologic factors have been related to patient outcome. We collected clinical, pathological, and molecular data of 28 patients with histologically confirmed SFT having at least one pathological factor associated with aggressive behavior. Molecular analysis to detect NAB2/STAT6 gene fusion, TP53, and/or TERT promoter mutation was performed. We analyzed the pathological factors predictive of recurrence/metastasis and compared with clinical outcome. The risk of metastasis was calculated using four previously described scoring systems. Histopathologically, all tumors revealed hypercellularity, 11 had ≥ 4 mitoses/10 HPF, and 12 showed necrosis. Dedifferentiation was observed in three tumors. STAT6 was positive in all cases. Desmin, p16, INSM1, and HTER immunoexpressions were detected in 14, 18, 21, and 46% of the SFT, respectively. The NAB2/STAT6 gene fusion was detected in 16 tumors. After a median follow-up of 34 months, 32.0% recurred, 32.1% metastasized, and 35.7% died of disease. TERT mutations were detected in almost half the tumors. Tumors with TP53 mutations or with TP53 and TERT promoter mutations were almost always classified as high risk, and the patients developed metastases and/or died of disease. Tumors with intermediate-risk and TERT mutation had a worse evolution. SFTs with adverse pathological parameters were not always related with a poor outcome, thus confirming the unpredictable clinical behavior of SFT. The inclusion of molecular factors (TP53 and TERT promoter status) may provide new prognostic indicators for future risk stratification systems, especially in the intermediate-risk group.

中文翻译：

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孤立性纤维性肿瘤：确定病理学不利因素的案例系列-对危险分层和分类的意义。

孤立性纤维性肿瘤（SFT）是间质病变的一种罕见类型，其中特定的临床病理因素已与患者预后相关。我们收集了28例经组织学证实为SFT的患者的临床，病理和分子数据，这些患者至少具有一种与攻击行为相关的病理因素。进行了分子分析以检测NAB2 / STAT6基因融合，TP53和/或TERT启动子突变。我们分析了预测复发/转移的病理因素，并与临床结果进行了比较。使用四个先前描述的评分系统计算转移的风险。在组织病理学上，所有肿瘤均显示细胞增生，11个有≥4个有丝分裂/ 10 HPF，12个显示坏死。在三个肿瘤中观察到去分化。STAT6在所有情况下均为阳性。Desmin，第16页，INSM1，分别在14％，18％，21％和46％的SFT中检测到HIF和HTER免疫表达。在16个肿瘤中检测到NAB2 / STAT6基因融合。中位随访34个月后，复发32.0％，转移32.1％，死亡35.7％。在几乎一半的肿瘤中检测到TERT突变。带有TP53突变或TP53和TERT启动子突变的肿瘤几乎总是被归类为高风险，并且患者发生转移和/或死于疾病。具有中度风险和TERT突变的肿瘤进化较差。病理参数不利的SFT并不总是与不良预后相关，因此证实了SFT的临床行为不可预测。包括分子因素（TP53和TERT启动子状态）可能为未来的风险分层系统提供新的预后指标，