腹膜后去分化脂肪肉瘤的CT诊断

目的结合病理探讨去分化脂肪肉瘤(DL)的CT表现及诊断价值。方法回顾性分析11例包括复发病例共15例次经手术及病理证实的去分化脂肪肉瘤的CT表现特点，并与病理对照。结果CT表现分为3组：(1)脂肪密度肿块深部见一分隔的等或高于肌肉密度肿块，2种成分之间分界截然，显微镜下见分化好的脂肪肉瘤区域向高度恶性非脂肪源性肉瘤区域突然过渡者10例，包括5例原发肿瘤及5例继发肿瘤。(2)等或高于肌肉密度肿块，瘤内脂肪密度成分少于10％者3例，为复发病例。(3)盆腹腔内多发病灶，脂肪密度肿块与等或高于肌肉密度肿块分别散发于不同部位者2例，为复发病例。去分化成分，平扫与肌肉密度相似(15／15)，12例增强扫描显示早期中度到显著不均匀强化(12／12)，有延迟强化。结论去分化脂肪肉瘤的CT表现有一定特点，动态增强扫描可反映肿瘤的强化特征，提供有价值的鉴别诊断依据，CT对于术前定性及指导病理取材有价值。

CT diagnosis of retroperitoneal dedifferentiated liposarcoma

Objective To investigate the value of CT in the diagnosis of dedifferentiated liposarcoma.Methods Fifteen surgical operations of dedifferentiated liposarcoma in 11 patients, confirmed by pathology, underwent plain (n=15) and contrast enhanced (n=12) CT scans. Two of the 12 lesions underwent dynamic multi-phase contrast scans. The CT features and the corresponding pathological basis were analyzed.Results The lesions were divided into 3 groups according to the fatty component and its distribution. The CT appearances were as follows: (1)a well delineated fatty component in the lesion and a closely apposed non-fatty region in 10 cases including 5 initial (5/5, 100%) and 5 recurrent (5/10, 50%), which depicted an abrupt transition from the well-differentiated area to the high-grade sarcoma component under microscope; (2)fatty component within the lesion was less than 10% in 3 recurrent (3/10, 30%); (3)fatty masses and non-fatty masses separately distributed in 2 recurrent cases (2/10, 20%). Contrast enhanced CT scan showed moderate to marked inhomogeneous enhancement in the early phase in all 12 lesions, and delay enhancement was also observed.Conclusion Dedifferentiated liposarcoma exhibited specific appearances as well delineated fatty component and closely apposed non-fatty region with apparent enhancement. Dynamic contrast CT scans play important roles in the diagnosis and differential diagnosis of dedifferentiated liposarcoma, and help pre-surgical grading and pathological sampling.