目的 回顾性分析术前误诊为肾细胞癌(RCC)而接受手术治疗的少脂肪型肾脏血管平滑肌脂肪瘤(AML)的CT表现,以期提高对此病变的认识.方法 5例少脂肪型AML患者(8个病灶)纳入AML组,17例肾透明细胞癌(CCRCC)作为对照1组,7例低强化RCC(LERCC,包括乳头状肾癌和嫌色细胞癌)作为对照2组,分析少脂肪型AML的CT征象,包括平扫高密度、肿瘤与肾实质交界的角征,增强扫描皮髓质期强化均匀与否.手工放置ROI并计算肿瘤的下述指标:皮髓质期瘤-皮强化比值和排泄期瘤-皮强化比值.结果 AML组5例8个瘤体均为均匀高密度,2例CCRCC为均匀高密度,1例以高密度为主,1例乳头状肾癌为不均匀高密度,各组间差异有统计学意义(P＜0.001).AML组和对照2组均在皮髓质期均匀强化(100％),与对照1组差异有统计学意义(P=0.004).AML组有7个,对照1组有10个,对照2组有7个瘤体为外凸型,AML组角征阳性率高于其余两组(P=0.003).无论皮髓质期和排泄期的瘤-皮强化比值均表现为对照2组显著低于AML组和对照1组(P均＜0.05),而后两者间差异无统计学意义(P=0.331、0.321).结论 易误诊为RCC的少脂肪型AML的可能CT表现包括:平扫高密度,外凸型者角征阳性,增强扫描均匀明显强化.如肾脏肿瘤有上述CT表现,应考虑到少脂肪型AML的可能.%Objective To retrospectively analyze CT manifestations of renal angiomyolipoma (AMD with minimal fat which was misdiagnosed as renal cell carcinoma (RCC), and to highlight the awareness of this disease. Methods Five AML patients (8 lesions) with minimal fat were enrolled in AML group. Seventeen patients with clear cell renal cell carcinoma (CCRCC) and 7 low-enhance RCC (LERCC, including papillary renal cell carcinoma and chromophobe cell renal carcinoma) were selected as control 1 and control 2 group, respectively. CT manifestations of AML with minimal fat were observed, including hyperintensity on plain CT, angle sign between the exophytic neoplasm and renal parenchyma as well as homogeneous enhancement of the renal neoplasm on corticomedullary phase. ROIs were placed manually and enhancement ratio of neoplasm-cortex in corticomedullay phase and excretory phase were calculated. Results Eight neoplasms in AML group were all homogeneous hyperintensity on plain CT. Two lesions in CRCC group showed homogeneous hyperintensity and 1 with predominant hyperintensity on plain CT. One papillary RCC in control 2 group showed predominant hyperintensity on plain CT. There was significant difference among the three groups (P<0. 001). All the tumors in AML group and control 2 group showed homogeneous enhancement in the corticomedullary phase (100%), which was significantly higher than those in control 1 group (P = 0. 004). Seven lesions in AML group, 10 in control 1 group and 7 in control 2 group were exophytic tumors. The positive angle sign in AML group appeared more frequently than that in the other two groups (P=0. 003). Enhancement ratio of neoplasm-cortex both in corticomedullay phase and excretory phase of control 2 group were lower than those of AML group and control 1 group (both P<0. 05), while the latter two groups had no significant difference (P=0. 331, 0. 321). Conclusion AMLs with minimal fat that maybe easily misdiagnosed on CT may show the following findings: Hyperintensity on plain CT, positive angle sign if exophytic as well as homogeneous enhancement on enhanced CT. When the above CT manifestations were noticed, awareness of AML with minimal fat was necessary for correct dagnosis.
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