肾乏脂肪血管平滑肌脂肪瘤与肾癌亚型的CT鉴别诊断

The Differential Diagnosis Of Minimal Fat Renal Angiomyolipoma with Subtypes Of Renal Cell Carcinoma

目的分析肾血管平滑肌脂肪瘤(Angiomyolipoma,AML)与肾癌亚型的CT表现,评价多层螺旋CT在肾乏脂肪AML与肾癌亚型的诊断与鉴别诊断价值。方法回顾性分析21例肾乏脂肪AML21例及93例肾癌(其中肾透明细胞癌73例,肾乳头状细胞癌11例,肾嫌色细胞癌9例)CT影像,比较肾乏脂肪AML与肾癌常见亚型MSCT多期扫描影像学表现,并用统计学软件(SPSS 18.0)进行统计学分析。结果薄层重建肾乏脂肪AML组发现微脂肪区域10例,占47.6%,肾癌组仅2例,均为透明细胞癌,两组比较有显著性差异(P<0.05)。肾透明细胞癌皮质期增强程度、排泄期衰减程度均大于肾乏脂肪AML(P<0.05),肾透明细胞癌大多呈不均匀强化而肾乏脂肪AML为均匀强化的居多(P<0.05)。肾乏脂肪AML在皮质期、实质期、排泄期的强化程度均大于肾乳头状细胞癌及嫌色细胞癌(P<0.05),而强化模式的比较无显著性差异(P>0.05)。结论薄层重建仔细寻找肿瘤内有无微脂肪成分是鉴别肾乏脂肪AML与肾癌的关键;对于无可见脂肪的肾AML,肿瘤的强化程度、强化模式是鉴别的重要手段,且需考虑到肾癌亚型的因素综合分析。少数不典型的良性肿瘤鉴别困难,应结合临床综合分析,必要时行活检,避免误诊导致过度治疗。

Objective To analyze the CT findings in renal angiomyolipoma with minimal fat and subtypes of renal cell carcinoma, and have a value evaluation of MSCT diagnosis and differential diagnosis of renal angiomyolipoma with minimal fat and subtypes of renal cell carcinoma. Methods A retrospective analysis was carried out on CT images of 21 cases of minimal fat renal angiomyolipomas and 98 cases of renal cell carcinoma（including 73 cases of clear cell renal carcinoma, 11 cases of papillary renal cell carcinoma, 9 cases of chromophobe renal cell carcinoma）. The differences of CT imaging features were compared between minimal fat AML and renal cell carcinoma and they were analyzed by using statistical software（SPSS 18）. Resultsesults TLC reconstruction showed ten cases of micro fat areas in the lipid-poor renal hamartoma group（47.6%） and two cases in the renal cell carcinoma group, with a significant difference（P0.05）. Degree of enhancement in corticomedullary phase（CMP） and the degree of attenuation in excretion phase of clear cell renal carcinoma were all larger than that of renal angiomyolipoma with minimal fat（P0.05）. Clear cell renal carcinoma was mostly shown heterogeneous enhancement while angiomyolipoma with minimal fat has substantially uniform strengthening（P0.05）. In the cortical phase, nephrographic phase and excretion phase, the degree of strengthening of angiomyolipoma with minimal fat was more than that of papillary renal cell carcinoma and chromophobe renal cell carcinoma（P0.05）, whereas there was no significant difference in excretion phase concerning the degree of attenuation（P0.05）, and the comparison regarding enhancement pattern was also of no significant difference（P0.05）. ConclusiononclusionThe key to identify renal angiomyolipoma with minimal fat from renal cell carcinoma is to carefully determine whether micro-fat ingredients were present in the tumor by TLC reconstruction. For angiomyolipoma with invisible fat, the degree of tumor enhancement and the enhancement pattern were the important means of identification. Besides, the comprehensive analysis for the factors of subtype of renal cell carcinoma needs to be taken into account. Few atypical renal angiomyolipoma with minimal fat were difficult to be distinguished, which should be combined with a comprehensive analysis; if necessary, biopsy should be given to avoid misdiagnosis and thus leading to overtreatment.