黏液纤维肉瘤的MRI表现及其病理学基础

Imaging features and relevant pathological changes of myxofibrosarcoma

目的:探讨黏液纤维肉瘤(MFS)的MRI表现及其病理基础,提高对本病的诊断水平。方法:回顾性分析16例经手术病理证实的MFS患者资料,就其MRI及病理进行总结分析;低度恶性组8例,中高度恶性组8例(中度恶性2例,高度恶性6例)。结果:14例位于浅筋膜下,2例位于肌间隙内;7例呈类圆形,6例呈梭形,3例呈不规则形,肿瘤最大径约4.6~13.2cm,平均7.6cm;MRI上,2例T1WI呈均匀稍高信号,14例呈混杂等/低信号,2例T2WI呈均匀高信号,14例呈混杂高信号,11例病变呈DWI混杂高信号,ADC均呈混杂低信号;10例增强扫描呈不均匀明显强化;15例可见"筋膜尾征",12例见瘤周水肿,12例病灶内见"双低信号征",11例见囊变、坏死,6例见黏液样变,其中6例囊变、坏死区及5例黏液样变区ADC值差异具有统计学意义(P<0.05);肿瘤大小、"双低信号征"及"尾征"于轻度恶性组、中高度恶性组之间差异无统计学意义(P>0.05)。瘤周水肿、囊变坏死及黏液样变于两组间差异均有统计学意义(P<0.05),且前两者多见于中高度恶性组,后者多见轻度恶性组;镜下疏松区富含黏液基质,并可见散在曲线形血管,细胞密集区见多发梭形肿瘤细胞,异型性明显,核分裂多见;免疫组化16例Vimemtin及13例CD34呈阳性。结论:MFS的MRI表现具有一定特征性,有助于术前诊断,最终确诊依赖病理。

Objective:To investigate MRI and relevant pathological features of myxofibrosarcoma(MFS).Methods:The MRI findings and pathological results of 16 cases with MFS proved by pathology were retrospectively analyzed.Eight cases were low-grade,2 cases were intermediate-grade,and 6 cases were high-grade.Results:Fourteen cases were located under the superficial fascia,2 cases were located in the muscular space,7 cases were round shapes,6 cases were spindle shapes,and 3 cases were irregular shapes.The tumors ranged from 4.6~13.2 cm in maximum diameter,with an average of 7.6 cm.On T1 WI,2 cases showed slightly hyper-intensity,14 cases were heterogeneous with signal intensity similar or lower than that of mus-cles,2 cases showed uniform high signal intensity on T2 WI,14 cases demonstrated mixed high signal intensity,11 cases showed mixed high signal intensity on DWI and hypo-intensity signal on ADC,10 cases presented heterogeneous enhance-ment.Fifteen cases showed"fascia tail signs",12 cases had peritumoral edema,12 showed"double low signal signs",11 cases demonstrated cysts and necrosis,6 cases showed mucoid degeneration.The difference of ADC value between 6 cases with cystic and necrotic and 5 cases with mucoid degeneration was statistically significant(P<0.05).Tumor size,"double low signal signs"and"tail signs"were not significantly different between low-grade group and intermediate-high-grade group(P>0.05).There were significant differences for peritumoral edema,cystic necrosis and mucoid degeneration between the two groups(P<0.05).Microscopically,the mucoid matrix was rich in loose area with curved blood vessels around it.Multiple spin-dle tumor cells could be seen in dense areas of cells.The heterogeneity was obvious,and mitosis was more common.Im-munohistochemically,all 16 cases were positive for vimentin,13 cases were positive for CD34.Conclusion:MFS has certain MRI characteristics which is helpful to improve the diagnostic accuracy,the final diagnosis still depends on pathology.