原发性四肢软组织脂肪肉瘤MRI表现与病理学对照

目的：探讨四肢软组织脂肪肉瘤MRI表现与组织分化程度的关系,提高诊断准确性。方法：对经手术、病理证实的10例原发性四肢软组织脂肪肉瘤的MRI表现和特征与术后病理标本进行回顾性对照分析,了解肿瘤的大小、形态、边界、信号特点和邻近组织结构侵犯的情况,以找出它们间的关系。结果：10例中分化成熟型5例（脂肪肉瘤中脂肪瘤样脂肪肉瘤4例,硬化型1例）,黏液型2例,多形性2例,1例去分化型。分化成熟型含有大量成熟脂肪,在T1、T2WI像均高或较高信号,肿瘤边界清楚、信号较均匀。粘液型脂肪肉瘤含大量粘液基质,有少量分化良好、增生的脂肪母细胞,在MRI上无或少量的脂肪信号,信号轻度不均匀。多形性脂肪肉瘤属高度恶性肿瘤,信号明显不均匀,通常无明显脂肪信号显示,周围组织结构受浸润和水肿,去分化型瘤体体积大,信号明显不均匀,增强明显强化。结论：MRI表现和特征能反映软组织脂肪肉瘤的组织学特点,可清楚地显示肿瘤的大小、边界、累及范围及与周围组织的关系,可初步评估肿瘤的分化及恶性程度。

MRI features of primary liposarcoma of extremities and comparison with pathological results

Objective：To analyze the MRI features of liposarcoma of the extremities and to correlate with the degree of histopathologic differentiation,so that to improve its diagnostic accuracy.Methods：The MRI findings of 10 cases with primary liposarcoma proved by operation and pathology were analyzed retrospectively.The tumor size,morphology,margination,signal characteristic,and relationship of the tumor to adjacent structures were also assessed,and correlated them with surgical pathology.Results：This group of liposarcoma included five histological types（2 subtypes involved）.There were 5 cases of well-differentiated liposarcoma,1 case of sclerosing liposarcoma,2 cases of myxoid liposarcoma,2 cases of pleomorphic,1 case of dedifferentiated liposarcoma.Well-differentiated liposarcom had a large amount of mature fat,relatively high signal lntensity（SI） on T1WI and T2WI,tumor was well defined homogeneous in SI,adjacent structures were not invaded readily.Myxoid liposarcoma consisted mainly of myxoid matrix,containing a few well-differentiated proliferating lipoblasts,demonstrating no or little signal on MRI characteristic for fat,mildly inhomogeneous.Plepmorpic liposarcoma was obviously hetergeneous,no signal characteristic for fat adjacent structures was infiltrated and edematous.Dedifferentiated liposarcoma had a pretty lager volume,SI had apparently inhomogeneous,which was highly enhanced.Conclusion：MR can reflect features of histology of liposarcoma of the extremities,demonstrate the exact boundaries of tumors,and assess the actual area and surrounding tissues.The degree of histology differentiation and malignancy can be evaluated on the basis of MRI findings of liposarcoma.