History:A 27-year-old woman presents with progressive vertigo, ataxia, and headaches.
病史：27岁女性，进行性眩晕、共济失调、头痛。
A head MRI scan was performed. Axial and sagittal T1-weighted, axial and coronal T1-weighted postcontrast, axial T2-weighted, and axial T2-weighted fluid-attenuated inversion-recovery (FLAIR) MR images are shown below.
行颅脑MRI扫描，轴位/矢状T1WI、轴位/冠状T1增强、T2WI、T2WI FLAIR图像如下所示。
病灶最大层面T2WI、T1WI、FLAIR、增强图像。
Findings
There is an avidly enhancing lobular mass with multiple internal cystic components centered in the posterior fossa measuring up to 4.3 cm. The mass is associated with the dura as it extends across the left tentorium cerebelli into the supratentorial region. Additionally, there are cerebrospinal fluid clefts, which suggests that the lesion is extra-axial. The mass does not exhibit restricted diffusion. There is mass effect on the fourth ventricle, which is nearly completely affected. There is obstructive hydrocephalus of the third and lateral ventricles with evidence of transependymal CSF resorption. There is vasogenic edema in the bilateral cerebellar hemispheres and vermis.
影像表现：
后颅窝见一大小约4.3cm分叶状肿物，明显强化，内见多发小囊变区；病变与硬脑膜关系密切，穿过左侧小脑幕进入幕上（见冠状增强）。病灶周围可见裂状脑脊液影（见轴位T2WI），提示病变位于脑外。肿物无明显弥散受限，第四脑室受压变扁，幕上梗阻性脑积水，三脑室及侧脑室可见室管膜下脑脊液再吸收表现（间质性水肿）。双侧小脑半球及小脑蚓部可见血管源性水肿。
Differential diagnosis
Meningioma
Solitary fibrous tumor of dura (meningeal hemangiopericytoma)
Medulloblastoma
Hemangioblastoma
Neurosarcoidosis
Dural metastases
Meningeal melanocytoma
Meningioma
Solitary fibrous tumor of dura (meningeal hemangiopericytoma)
Medulloblastoma
Hemangioblastoma
Neurosarcoidosis
Dural metastases
Meningeal melanocytoma
鉴别诊断：
脑膜瘤
硬脑膜孤立性纤维瘤（脑膜血管外皮细胞瘤）
髓母细胞瘤
血管母细胞瘤
神经系统结节病
硬脑膜转移瘤
脑膜黑色素瘤
脑膜瘤
硬脑膜孤立性纤维瘤（脑膜血管外皮细胞瘤）
髓母细胞瘤
血管母细胞瘤
神经系统结节病
硬脑膜转移瘤
脑膜黑色素瘤
Diagnosis: Solitary fibrous tumor of dura (meningeal hemangiopericytoma)
最后诊断：硬脑膜孤立性纤维瘤（脑膜血管外皮细胞瘤）
Discussion 讨论
Solitary fibrous tumor of dura
(meningeal hemangiopericytoma)
Pathogenesis发病机制
Solitary fibrous tumors (SFT) were originally described as primary neoplasms of the visceral pleura, well-encapsulated spindle-cell tumors that only became symptomatic by mass effect. However, they were found to have a mesenchymal origin and were seen in numerous extrapleural sites, including within the central nervous system (intraspinal, intracranial, and along cranial nerves).
孤立性纤维瘤（SFT）最初被认为是脏层胸膜的原发性肿瘤，包膜完整的梭形细胞肿瘤，有占位效应时产生相应症状。然而，它常被发现为间叶细胞起源，发生在许多胸膜以外的部位，包括中枢神经系统内（椎管内、颅内、颅神经走行区）。
Hemangiopericytomas (HPC) were described as a distinct entity, classified as a subtype of meningiomas, thought to arise from smooth muscle pericytes of dural capillaries. However, like solitary fibrous tumors, they were found to arise from fibroblasts and share the same molecular genetics as SFTs. In fact, SFTs and HPCs were combined into the same entity in the 2016 World Health Organization (WHO) classification of central nervous system tumors (with hemangiopericytomas now being an obsolete term). SFT/HPC is a highly cellular and vascular tumor (WHO grades I to III) that often has systemic metastases at diagnosis (liver, lung, and bones). Classic histologic features include a “staghorn” branching stromal vascular pattern.
血管外皮细胞瘤（HPC）曾被认为是独立存在的脑膜瘤的一种亚型，起源于硬脑膜毛细血管平滑肌的周细胞。然而，与SFT一样，它被发现起源于纤维母细胞，具有与SFT相同的分子遗传学。事实上，CNS肿瘤2016版WHO分类中，SFTs和HPCs被认为是同一种肿瘤（HPCs这个术语已经过时）。孤立性纤维瘤是一种富含细胞和血管的肿瘤（WHO I~III），可出现全身转移（肝、肺及骨）。组织学典型表现为间质血管呈“鹿角样”分支形状。
Epidemiology 流行病学
They account for less than 1% of intracranial tumors and are most often found in younger adults (ages 30 to 45) with a slightly higher prevalence in males.
在颅内肿瘤中所占比例不足1%，常见于较年轻的成人（30-45岁），略多见于男性。
Clinical presentation 临床表现
Symptoms are secondary to mass effect and include headaches, seizures, and focal neurologic dysfunction.
临床症状与肿瘤的占位效应有关，包括头痛、癫痫、局部神经功能障碍。
Diagnosis 诊断
Although imaging findings may distinguish an SFT/HPC from a meningioma, pathology is necessary to confirm the diagnosis, ideally by immunohistochemistry identifying NAB2-STAT6 fusion.
尽管影像表现可能有助于鉴别SFT/HPC与脑膜瘤，但仍需借助病理（免疫组化）明确诊断。
Imaging findings影像表现
SFT/HPCs are solitary, lobulated, heterogeneous masses.
They are highly vascular and avidly enhancing.
They can be infratentorial and/or supratentorial in location.
Most common locations include the occipital region and may involve the falx, tentorium, or dural sinuses.
They are extra-axial but may have a narrow base of dural attachment.
On CT, there may be erosion of adjacent bone but no calcifications or hyperostosis.
On MRI, they will be isointense to gray matter on T1- and T2-weighted imaging, but mass effect on adjacent brain will display T2/FLAIR hyperintensity.
On MR spectroscopy, there is often a myo-inositol peak.
Meningiomas are usually smoother, have a broader dural tail, cause hyperostosis, and have a central spoke-wheel vascular supply.
SFT/HPCs are solitary, lobulated, heterogeneous masses.
They are highly vascular and avidly enhancing.
They can be infratentorial and/or supratentorial in location.
Most common locations include the occipital region and may involve the falx, tentorium, or dural sinuses.
They are extra-axial but may have a narrow base of dural attachment.
On CT, there may be erosion of adjacent bone but no calcifications or hyperostosis.
On MRI, they will be isointense to gray matter on T1- and T2-weighted imaging, but mass effect on adjacent brain will display T2/FLAIR hyperintensity.
On MR spectroscopy, there is often a myo-inositol peak.
Meningiomas are usually smoother, have a broader dural tail, cause hyperostosis, and have a central spoke-wheel vascular supply.
影像表现
单发肿物，有分叶，不均质；
富血供，明显强化；
幕下、幕上均可见
常见发病部位：枕部，可累及大脑镰、小脑幕及硬脑膜窦；
脑外病变，窄基底与硬脑膜相接；
CT上可表现邻近骨质受侵，无钙化及骨质增生；
MRI T1WI、T2WI上肿瘤与灰质信号一致，占位效应可导致周围脑实质在T2/FLAIR上表现为高信号；
MRS上常可见肌醇峰；
脑膜瘤表现为边缘光滑，宽基底及硬膜尾征，骨质增生，中心可见轮辐样供血血管。
单发肿物，有分叶，不均质；
富血供，明显强化；
幕下、幕上均可见
常见发病部位：枕部，可累及大脑镰、小脑幕及硬脑膜窦；
脑外病变，窄基底与硬脑膜相接；
CT上可表现邻近骨质受侵，无钙化及骨质增生；
MRI T1WI、T2WI上肿瘤与灰质信号一致，占位效应可导致周围脑实质在T2/FLAIR上表现为高信号；
MRS上常可见肌醇峰；
脑膜瘤表现为边缘光滑，宽基底及硬膜尾征，骨质增生，中心可见轮辐样供血血管。
Treatment and prognosis 治疗及预后
They require total surgical resection with preoperative catheter embolization.
Adjuvant radiotherapy helps reduce the rate of recurrence.
They have a high risk of local recurrence (50% to 90%) and metastases many years later.
Patients have a median survival of three to six years without metastases and two years with metastases.
They require total surgical resection with preoperative catheter embolization.
Adjuvant radiotherapy helps reduce the rate of recurrence.
They have a high risk of local recurrence (50% to 90%) and metastases many years later.
Patients have a median survival of three to six years without metastases and two years with metastases.
术前行导管栓塞，而后手术完整切除；
辅助放疗有助于降低复发率；
局部复发率较高(50%-90%) ，数年后可发生转移；
患者中位生存时间为6年（无转移）及2年（有转移）。
术前行导管栓塞，而后手术完整切除；
辅助放疗有助于降低复发率；
局部复发率较高(50%-90%) ，数年后可发生转移；
患者中位生存时间为6年（无转移）及2年（有转移）。
The supreme happiness of life is the conviction that we are loved.
生活中最大的幸福就是，坚信有人爱着我们。
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