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孤立性纤维瘤(solitary fibrous tumors,SFT)是一种罕见的间叶组织肿瘤,在软组织肿瘤中约占2%[1]。SFT最早被认为发生于胸膜、心包膜、腹膜内间皮或间皮下的肿瘤,但随着病理学的发展,SFT被发现是一种发生于成纤维细胞或肌纤维母细胞且遍布全身的软组织肿瘤,病理上也具有多样性[2]。由于SFT与血管外皮细胞瘤组织学起源相同,又具有相似的细胞病理学、临床影像学等表现,导致SFT常被误诊为血管外皮细胞瘤[3]。目前,世界卫生组织对SFT与血管外皮细胞瘤做了明确规定,将多数血管外皮细胞瘤的病例划分为SFT[4]。
研究发现,胸外SFT较胸腔内的更常见[5]。通常表现为生长缓慢、边界清晰的软组织肿瘤,无特异性临床症状,偶尔表现为压迫症状。腹盆腔的SFT亦是如此。复习国内外文献,关于发生于腹盆腔SFT的文献报道不多,本研究通过回顾性分析腹盆腔SFT的CT和MRI影像学表现及特征,旨在提高对其的诊断水平。
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13例患者的肿瘤直径为(10.53±6.21) cm,最大直径为2.7~23.4 cm。12例患者的病灶边界清晰,与周围结构有明显分界,仅有1例发生于胃底的病灶,与周围胃壁结构界线不清。8例患者的病灶呈深浅不一的分叶状或类圆形。CT平扫表现为等密度或等低密度(相对于肌肉),7例患者的病灶内出现囊变,平扫密度不均匀,1例出现钙化灶。动态增强扫描后病灶强化各异,动脉期扫描有11例表现为明显不均匀强化,病灶边缘强化明显,8例病灶内见片状、裂隙状或瘢痕状低强化区(图1中A);静脉期或延迟期扫描向中心渐进性强化(图1中B、C),静脉期及延迟期表现为延迟强化,2例表现为轻中度强化,1例表现为明显均匀渐进性强化。除上述强化特征外,10例患者的病灶在动脉期内可见点状及线状明显强化血管(图1中A),均以病灶边缘分布为主;8例病灶周围可见迂曲血管(图1中D),血管扩张程度与病灶大小大致呈正比。
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5例患者的肿瘤直径为(11.93±3.21) cm,最大直径为10.0~13.4 cm。5例患者的病灶边界均清晰,与周围结构有明显分界。4例病灶呈深浅不一的分叶状,T1加权成像呈均匀或不均匀低信号及等低信号(相对于肌肉)(图2中A),T2加权成像信号较为复杂,3例出现囊变表现为高信号,4例内见瘢痕状及片状低信号区(图2中B),其中2例既出现囊变高信号区又出现斑片状低信号区,病灶呈高、稍高及低混合信号;均匀等高信号1例。有5例患者的病灶内部均出现低信号流空血管影。动态增强扫描后病灶强化方式不同,动脉期扫描有4例表现为明显不均匀强化,病灶边缘强化明显,4例病灶内见片状、裂隙状或瘢痕状低强化区(图2中C);静脉期或延迟期扫描向中心渐进性强化(图2中D),病灶内部可见瘢痕状及片状动脉期低强化区。1例表现为均匀强化;5例病灶在动脉期内可见点状及线状明显强化血管(图2中C),以病灶边缘分布为主。
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18例SFT患者中,最终病理结果显示7例为恶性,11例为良性。对照病理结果详细分析良恶性病变影像学表现的差异性,良性病例中囊变7例,恶性病例中囊变5例;增强扫描中,呈明显不均匀强化方式的良性病例8例,恶性6例。对鉴别良恶性的3个指标(大小、边界、形态)进行统计学分析结果发现,恶性病变通常直径较大,7例恶性病变中,有5例大于平均值[(10.88±5.62) cm];而良性病变中仅有2例大于平均值,差异具有统计学意义(χ2=5.103,P=0.039)。本研究中只有1例病变边界不清,且为良性病例。由表1可知,在良恶性病变中,边界之间的比较差异无统计学意义(χ2=0.674,P=0.611)。肿瘤形态呈不规则分叶状的良恶性患者各有6例,规则无分叶的病例中良性5例、恶性1例,在良恶性病变中肿瘤形态的良恶性比较,差异无统计学意义,其他具体结果见表1。
病变性质 例数 大小 边界 形态 大于均值 小于均值 清晰 不清晰 不规则分叶 规则无分叶 良性 11 2 9 10 1 6 5 恶性 7 5 2 7 0 6 1 χ2值 5.103 0.674 1.870 P值 0.039 0.611 0.199 注:表中,肿瘤直径的均值为(10.88±5.62)cm。 表 1 18例孤立性纤维瘤患者良恶性病变的3个影像学征象分析(例)
Table 1. Analysis of three imaging features of pelvic solitary fibrous tumors of 18 case solitary fibrous tumors
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本研究中的所有患者均行手术切除肿瘤,术中探查到肿瘤质韧,10例患者的肿瘤周围血管扩张迂曲,部分肿瘤表面布满迂曲血管,与影像学表现高度吻合。12例患者的肿瘤与周围脏器无浸润、黏连,影像学表现为边界清晰,2例病灶周围可探及子灶。病理结果显示,14例患者的肿瘤有完整包膜,边界清楚;肿瘤切面呈灰白色、质韧,肿瘤内血管丰富与动脉期影像学表现相似。光镜下显示,肿瘤均由疏密不均的梭形细胞组成,呈束状、波纹状排列,间质富于胶原伴玻璃样变性。12例肿瘤可见胶原纤维化结构,该结构与影像学延迟强化结构高度吻合。7例见细胞异型性及核分裂象,提示恶性。免疫组化结果显示,13例患者的CD34为(+)、4例为(++)、1例为(+++);12例患者的B淋巴细胞瘤2基因为(+)、6例为(–)。
腹盆腔孤立性纤维瘤的CT和MRI表现及征象分析
CT and MRI features of solitary fibrous tumors in abdomen and pelvis
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摘要:
目的 分析腹盆腔孤立性纤维瘤(SFT)的CT和MRI影像学表现及征象,提高对其的认识和诊断的准确性。 方法 回顾性分析2008年1月至2017年6月经手术病理证实的18例腹盆腔SFT患者[男性9例、女性9例,年龄41~71(53.0±10.6)岁]的影像学表现、临床及病理资料。18例患者中,13例行CT平扫和动态增强扫描,5例行MRI平扫和动态增强扫描,分析肿瘤的大小(最大径)、形态、密度或信号、动态增强特点、动脉期肿瘤体内血管及肿瘤周围有无血管等情况。采用卡方精确检验分析肿瘤大小、边界及形态与良恶性肿瘤的关系;Fisher检验比较三者在良恶性肿瘤中表现的差异性。 结果 ① CT影像学表现:13例患者的肿瘤直径为(10.53±6.21) cm,最大直径为2.7~23.4 cm。12例患者肿瘤的病灶边界清晰;8例呈分叶状,7例出现囊变,1例有钙化。CT动态增强扫描显示有11例呈不均匀明显强化;8例病灶内出现延迟强化区,2例表现为轻中度强化;10例动脉期病灶内显示强化血管;8例病灶周围出现迂曲血管。② MRI影像学表现:5例患者的肿瘤直径为(11.93±3.21) cm,最大直径为10.0~13.4 cm。5例患者的病灶边界均清晰;4例病灶呈分叶状;T2加权成像显示有3例出现囊变,4例病灶内见瘢痕状及片状低信号区,1例均匀等高信号;5例出现流空血管影。4例病灶表现为明显不均匀强化;4例病灶内出现延迟强化区;1例表现为均匀强化;5例动脉期在病灶内显示强化血管。③病理结果显示:18例SFT患者中,7例为恶性、11例为良性。7例恶性SFT患者中,有5例病灶最大直径超过平均直径[(10.88±5.62) cm],而良性SFT患者中仅有2例最大直径超过平均直径,差异有统计学意义(χ2=5.103,P=0.039)。 结论 腹盆腔SFT的CT及MRI表现呈多样性,当腹腔内出现丰富的血供伴瘢痕状、片状延迟强化肿瘤,同时瘤体周围出现迂曲血管及瘤体内出现点、条状动脉期强化血管的表现有助于诊断,且MRI中T2加权成像出现低信号也具有一定的诊断价值。 -
关键词:
- 孤立性纤维瘤 /
- X线计算机,体层摄影术 /
- 磁共振成像
Abstract:Objective To observe the CT and MRI results of solitary fibrous tumors(SFT) in the abdomen and pelvis, analyze their characteristic imaging, and improve the accuracy of diagnosis and understanding of the disease. Methods Retrospective analysis of 18 cases confirmed by pathology from January 2008 to June 2017[9 men, 9 women, age 41–71(53.0±10.6) years old] through imaging findings and clinical and pathological data of patients with pelvic SFT. Among the 18 patients, 13 received dynamic CT and 5 received dynamic MRI. The tumor size(maximum diameter), morphology, density or signal, dynamic enhancement characteristics, arterial tumor vessels, and tumors were mainly analyzed. Fisher's exact test was conducted to examine the relationship between tumor size, boundary, and morphology of benign and malignant tumors. The differences among the three characteristics in malignant tumors were determined by Fisher' s test. Results ① Characteristics of CT imaging: The maximum diameter of tumor lesions in the 13 patients with CT was(2.7–23.4) cm, and the mean diameter was(10.53±6.21) cm. Among the 13 cases, 8 were lobulated and 7 exhibited cystic degeneration. One patient showed calcification. Furthermore, 11 cases of nonuniform enhancement by dynamic enhancement was observed. Delayed enhancement was observed in 8 cases. Mild to moderate enhancement was observed in 2 cases. In 10 cases, pointy and linear enhancement of vessels could be seen at the arterial stage, and in 8 cases, tortuous vessels were observed around the lesions. The maximum diameter of the lesions was (10.0–13.4) cm and the mean diameter was(11.93±3.21) cm. ② Characteristics of MRI: The lesion boundaries of 5 patients were clear, and the lesions were lobulated in 4 of 5 patients. In T2 weighted imaging, cystic changes were observed in 3 patients. In 4 cases, scarlike or flaky low-signal areas were found in the lesions, 1 case showed uniform isobaemic signals, and 5 cases presented empty vascular shadows. Moreover, 4 cases indicated an obvious uneven enhancement. Delayed enhancement was observed in 4 cases, and uniform enhancement was observed in 1 case. In 5 cases, vessels were strengthened in the lesion at the arterial stage. ③ Pathology results showed that among the 18 SFT cases, 7 were malignant and 11 were benign. For the malignant SFT, 5 of 7 cases exceeded the average diameter[(10.88±5.62) cm], whereas for the benign SFT, only 2 of 11 cases exceeded the mean. The maximum diameter was different between the benign and malignant lesions(χ2=5.103, P=0.039), showing statistical significance. Conclusions Although radiological findings on abdomino-pelvic SFT vary between dynamic contrast enhanced CT and MRI, a hypervascular mass with delayed enhancement is the imaging feature. Peripheral tortuous vessels and filiform vessels in the lesion may reinforce the diagnosis. The low signal of T2 weighted imaging in MRI also has a certain diagnostic value. -
表 1 18例孤立性纤维瘤患者良恶性病变的3个影像学征象分析(例)
Table 1. Analysis of three imaging features of pelvic solitary fibrous tumors of 18 case solitary fibrous tumors
病变性质 例数 大小 边界 形态 大于均值 小于均值 清晰 不清晰 不规则分叶 规则无分叶 良性 11 2 9 10 1 6 5 恶性 7 5 2 7 0 6 1 χ2值 5.103 0.674 1.870 P值 0.039 0.611 0.199 注:表中,肿瘤直径的均值为(10.88±5.62)cm。 -
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