不同类型肝脏血管周上皮样细胞肿瘤的影像特点

目的探讨不同类型肝脏血管周上皮样细胞分化的肿瘤(PEComa)的CT及MRI影像学特征。方法回顾性分析我院2014年7月~2018年7月经手术病理证实的12例肝脏PEComa患者的影像学资料,分析病灶在CT及MRI图像上的位置、密度及信号特点、强化形式。结果含脂肪型病灶肉眼可见的脂肪成分无明显强化,而软组织成分强化明显,动态增强扫描病灶动脉期显著强化并见到瘤内血管,门脉期及延时期出现中轻度强化,并可见环形强化的假包膜。无脂肪型呈实质性软组织肿块,肉眼不可见脂肪成分,动态增强扫描病灶动脉期呈明显均质强化,可见粗大扭曲的畸形血管和动脉瘤样结节状强化,门脉期及平衡期呈延时强化改变。由于病灶缺少正常肝细胞,肝胆特异期病灶对比剂摄取呈低信号改变。其中含脂肪型需与血管平滑肌脂肪瘤鉴别,但影像学缺乏特异性,无脂肪型几乎全部误诊为肝细胞癌。结论肝脏PEComa具有独特的免疫组化特征,如果依据病灶内是否含有脂肪成分来分型,影像学表现具有一定的特性,但是病变在表观扩散系数图及肝胆特异期没有特异性,不能作为单独的诊断依据。乏脂肪型PEComa临床术前误诊概率较大,因此放射科医生加强对此病的认识具有重要的意义。

Imaging features of hepatic perivascular epithelioid cell tumors in different types

  Objective  To investigate the CT and MRI features of hepatic perivascular epithelioid cell differentiation tumors (PEComa) in different types.  Methods  The imaging data of 12 patients with liver PEComa confirmed by surgical pathology from July 2014 to July 2018 in our hospital were retrospectively analyzed to analyze the location, density and signal characteristics, and form of enhancement of the lesions on CT and MRI images.  Results  The fat-containing lesions showed no significant enhancement of the fatty component with the naked eye, while the soft-tissue component was significantly enhanced. Dynamic enhancement scans showed significant enhancement in the arterial phase and intra-tumoural vessels, and moderate to mild enhancement in the portal and delayed phases, with a circularly enhanced pseudo-envelope. In fat-deficient type, which was mainly characterized by a substantial soft tissue mass, the fat components are invisible to the naked eye. Dynamic enhancement scan showed marked homogeneous enhancement in the arterial phase of the lesion. with coarse distorted malformed vessels and aneurysmal nodular enhancement visible in the portal and equilibrium phases, delayed enhancement in the portal and equilibrium phases. Due to lack of normal hepatocytes in the lesions, the hepatobiliary specific phase showed low signal without contrast uptake. The fat-containing type tumors need to be differentiated from angiomyolipoma, but the lack of specificity in imaging means that the non- fatty type is almost always misdiagnosed as hepatocellular carcinoma.  Conclusion  There is unique immunohistochemical features in hepatic PEComa. If it is staged according to the presence or absence of a fat component, the imageology manifestations have certain characteristics. However, the lesions have no specificity in ADC or hepatobiliary specific phase, and cannot be used as a separate diagnostic basis. The probability of misdiagnosis before clinical procedures is relatively high in fat-deficient type, so it is important for radiologists to be more aware of this condition.