摘要：

研究背景 孤立性纤维性肿瘤是纤维母细胞起源的间叶性梭形细胞肿瘤，多发生于胸膜、纵隔、头颈部、四肢和躯干的皮下和深部软组织。发生于中枢神经系统者少见，多附着于脑（脊）膜，完全位于脑室内而与硬膜无关联者罕见。本文报告1 例脑室内原发性孤立性纤维性肿瘤患者，分析其影像学和临床病理学特征，并复习相关文献，探讨其诊断与鉴别诊断要点。方法与结果 男性患者，50 岁。临床表现为进行性加重的持续性头痛2 月余。头部CT 显示右侧侧脑室三角区内分界清楚的略高密度孤立性结节。MRI 显示右侧侧脑室内占位性病变，T₁WI 呈等信号、T₂WI 呈高低混杂信号，伴周围脑组织轻度水肿，肿瘤组织内可见黑白相间的“阴阳征”，增强扫描呈明显不均匀强化。MRA 显示肿瘤富血管，表现为持续性强化。手术全切除肿瘤。术中可见肿瘤完全位于侧脑室内，灰红色，团状块，质地中等，无包膜，与脉络丛相连，血供丰富。组织学形态显示，肿瘤组织由梭形细胞、胶原基质和丰富的血管构成，部分区域呈细胞丰富区和稀疏区交替分布构象，伴灶性间质黏液变性。部分区域肿瘤细胞排列密集、围绕不同管径的“树枝”状或“鹿角”样血管呈血管周细胞瘤样生长，细胞异型性不明显，核分裂象少见，肿瘤组织内未见出血坏死灶。免疫组织化学染色，肿瘤细胞弥漫性表达波形蛋白、CD34 和Bcl-2，灶性表达CD99，不表达细胞角蛋白、上皮膜抗原、胶质纤维酸性蛋白、S-100 蛋白、平滑肌肌动蛋白和结蛋白。网织纤维染色显示肿瘤组织内网状纤维丰富，部分区域网状纤维包绕肿瘤细胞。荧光原位杂交检测显示SYT 基因断裂呈阴性，不存在t（X；18）（p11；q11）易位。病理诊断为（右侧侧脑室内）原发性孤立性纤维性肿瘤。结论 脑室内孤立性纤维性肿瘤临床罕见，由于缺乏特征性影像学表现和组织学形态复杂多样，给术前明确诊断带来一定困难。由于孤立性纤维性肿瘤与血管周细胞瘤在组织学形态和免疫表型存在延续和重叠，故考虑二者属同一肿瘤谱系，建议联合应用“孤立性纤维性肿瘤/血管周细胞瘤”的诊断术语。由于该肿瘤发病部位少见，临床应提高警惕，注意与其他具有相似组织病理学构象的疾病相鉴别。

 

关键词: 孤立性纤维瘤, 脑室, 免疫组织化学, 原位杂交,  荧光, 病理学

Abstract:

Background  Solitary fibrous tumor (SFT) is a mesenchymal neoplasm of specialized fibroblastic lineage, which frequently occurs in the subcutaneous and deep soft tissue of pleura,mediastinum, head and neck, extremities and trunk. Although most SFTs of the central nervous system (CNS) are dural based, a small subset presents as intraventricular without dural connection. It is a diagnostic challenge for radiologists and histopathologists to differentiate intraventricular SFT from other lesions, such as intraventricular meningioma, synovial sarcoma and Schwannoma, because of the similarities in radiological and histological findings. Herein we describe one case of unusual intraventricular primary SFT in right lateral ventricle. The radiology and clinicopathology of this lesion, as well as its differential diagnosis are discussed. Methods  The clinical data of one patient with intraventricular SFT occurring in right lateral ventricle was presented retrospectively. Gross totally resected mass was routinely paraffin embedded and stained with hematoxylin and eosin. Dako EnVision immunohistochemical staining system was used to detect antigen expressions, including vimentin (Vim), cytokeratin(CK), CD34, CD99, Bcl-2, epithelial membrane antigen (EMA), glial fibrillary acidic protein (GFAP), S-100 protein (S-100), smooth muscle actin (SMA) and desmin (Des). Results  A 50-year-old man presented with progressively aggravated headache for over 2 months. CT revealed a slightly high-density mass in trigone of right lateral ventricle. MRI showed an intraventricular mass with isointense signal on T₁WI, and mixed hyperintensity and hypointensity signal with "black and white pattern" on T₂WI. The mass revealed heterogeneous enhancement after gadolinium administration. Preoperative magnetic resonance angiography (MRA) displayed a highly vascularized lesion with late and persistent enhancement. During surgery, the mass was grey-red, had no capsule and connected with choroid plexus, with moderate texture and rich blood supply. It was located in lateral ventricle entirely. The tumor was removed totally. Microscopic examination showed that the mass was composed of spindle cells, dense collagenous matrix, and prominent blood vessels. In some areas, the hypocellular and alternating hypercellular arrangement, and perivascular hyalinization were found. The tumor was lack of any specific arrangement, resulting in a "patternless pattern". The myxoid matrix was observed in some areas of tumor. However, in other areas, the tumor was composed of markedly spindle cells with branching or "staghorn" vessels, resembling hemangiopericytoma. The spindle tumor cells showed mild atypia without active mitoses and necrosis. Immunohistochemically, the tumor cells were diffusely positive for Vim, CD34 and Bcl-2, focally positive for CD99, and were negative for CK, EMA, GFAP and S-100, SMA and Des. Reticular fiber staining revealed rich reticular fibers within the tumor tissue, and a pericellular pattern was also seen. Fluorescence in situ hybridization (FISH) assay for SYT rearrangement showed there was absence of t (X; 18) (p11; q11) in the tumor cells. Based on clinical presentation and histological findings, a final diagnosis of intraventricular primary SFT in right lateral ventricle was made according to the criteria of WHO classification. The patient did not received radiotherapy and was followed-up for one year, without any neurological deficit or signs of recurrence. Conclusions  Intraventricular SFT is extremely rare and a definite diagnosis should be made under microscopic examination because the preoperatively radiological appearance does not differ from other tumors occurring in ventricle. Since a spectrum between SFT and hemangiopericytoma has been suggested because of overlapped morphological and immunohistochemical features, a diagnostic term of "SFT/ hemangiopericytoma" is suggested for those lesions occurring in CNS. Due to the rarity of its site, strictly differential diagnosis should be made when an isolated SFT is encountered in ventricles.

Key words: Solitary fibrous tumors, Cerebral ventricles, Immunohistochemistry, In situ hybridization, fluorescence, Pathology