腹膜后淋巴管平滑肌瘤病的影像学表现及文献复习

Imaging features of retroperitoneal lymphangioleiomyomatosis and literature review

目的总结分析腹膜后淋巴管平滑肌瘤病(LAM)的影像学表现,以提高影像医师对该疾病的认识。方法回顾性分析8例腹膜后LAM的临床特点、影像表现及病理特征并进行文献复习。结果CT表现为腹膜后不规则形囊实性肿块或增大淋巴结,病变边界清楚,可由腹膜后延伸至纵隔和/或盆腔。病灶实性成分密度均低于邻近腰大肌,平均CT值为24HU,囊性成分平均CT值为13HU。CT动态增强扫描显示肿瘤实性成分及分隔呈缓慢持续强化,延迟期强化程度呈轻至中度。MRI表现为腹膜后不规则形囊性分隔样肿块影,实性成分在T1WI及脂肪抑制T2WI上呈低信号,在扩散加权成像(DWI)上呈稍高信号。病理检查镜下可见肿瘤细胞由增生的短梭形细胞和衬以扁平内皮的网状或窦样腔隙组成。免疫组化显示,8例均表达了肌源性标志物(平滑肌肌动蛋白、结蛋白等)、黑色素标志物(HMB45、MelanA)及内皮细胞标志物(CD34、CD31和D2-40)中的一种或多种。结论腹膜后LAM的影像表现有其特征性,有助于提高对该病的诊断准确性。

Objective To summarize and analyze the MRI findings of retroperitoneal lymphangioleiomyomatosis(LAM)in order to enhance the understanding of radiologists.Methods The clinical features,imaging manifestations,and pathological characteristics of 8 cases of retroperitoneal LAM were retrospectively analyzed,and the literatures were reviewed.Results CT revealed an irregularly shaped cystic solid retroperitoneal mass or enlarged lymph nodes with clearly defined lesion border.The mass may extend from the retroperitoneum to the mediastinum and/or pelvis.The density of the solid component of the lesion was lower than that of the adjacent psoas major muscle,with an average CT value of 24 HU,while the average CT value of the cystic component was 13 HU.CT dynamic enhancement scans demonstrated slow and consistent enhancement of the solid component and septum,with mild to moderate enhancement in the delayed phase.MRI showed an irregularly shaped cystic septum-like mass in the retroperitoneum,while the solid compent showed low signal intensity on T1WI and fat-suppressed T2WI,and slightly high signal intensity on diffusion-weighted imaging(DWI).Pathological microscopy showed that the tumor cells consisted of proliferating short spindle cells and reticular or sinusoidal cavities lined with flat endothelium.Immunohistochemistry revealed that all 8 cases expressed one or more of myogenic markers(smooth muscle actin,junctional proteins,etc.),melanocyte markers(HMB45,Melan A),and endothelial cell markers(CD34,CD31,and D2-40),respectively.Conclusion The imaging findings of retroperitoneal LAM exhibit distinct characteristics that can contribute to an accurate diagnosis of the disease.