肺外炎性肌纤维母细胞瘤的影像学表现及病理对照分析

Analysis of imaging manifestations and pathological findings in extrapulmonary inflammatory myofibroblastic tumors

目的:探讨肺外炎性肌纤维母细胞瘤(extrapulmonary inflammatory myofibroblastic tumor,EPIMT)的CT与MRI表现。方法:回顾性分析2011年1月至2019年8月天津医科大学肿瘤医院经手术或穿刺病理及免疫组织化学证实的30例EPIMT患者影像学资料,总结病灶部位、大小、形态、边界、密度/信号、强化方式等影像表现特征。结果:30例EPIMT中,28例为单发病灶、2例为双发病灶。30例患者的32个肿瘤中,20个形态不规则、11个呈圆形或椭圆形、1个呈多结节融合状;病灶多边界不清,侵犯周围组织或与之黏连;8个其内可见囊变坏死,钙化及出血少见;多数病例CT增强检查后呈明显或中度强化,以渐进性持续强化为主,少数呈"慢进慢出"的强化方式;9例MRI增强检查后均表现为中度或明显延迟强化。免疫组织化学法结果显示,Ki-67增殖指数平均值<5%的例数约占50.0%,Vimentin、SMA及ALK阳性率分别为93.3%、86.7%及31.8%,S-100阴性率81.8%。结论:EPIMT的影像学表现为单发、边界不清伴絮状渗出、平扫呈均匀密度/信号,强化方式"渐进性持续强化"或"慢进慢出",瘤周出现淋巴结。对照分析病理总结病变的影像特征,旨在提高影像诊断准确性,并对分型有提示作用。

Objective:To describe the CT and MRI manifestations of extrapulmonary inflammatory myofibroblastic tumors(EPIMT).Methods:A retrospective analysis of images from 30 patients in Tianjin Medical University Cancer Institute and Hospital from January 2011 to August 2019 of EPIMT confirmed by surgery or puncture pathology and immunohistochemistry was conducted.The features examined included lesion location,size,shape,boundary,density/signal,and enhancement pattern.Results:Of the 30 cases,28 were determined to have a single isolated tumor,while 2 cases had two isolated tumors.Among the 32 tumors,20 had an irregular shape and 11 were round or oval,while a single tumor had the appearance of a multinodular fusion.Most of the lesions had ill-defined borders and showed signs of invading or adhering to the surrounding tissue.Cystic degeneration and necrosis were seen in 8 tumors,with calcification and hemorrhage also occasionally observed.On contrast-enhanced CT scans,significant or moderate enhancement was observed in most cases,mainly with a progressive and continuous enhancement pattern.A few cases showed heterogeneous enhancement with a slow wash in and slow wash out pattern.On contrast-enhanced MRI,9 cases demonstrated moderate or significantly delayed enhancement.Immunohistochemical staining showed a Ki-67 proliferation index of less than 5%in 50%of the tumors.Positive staining for Vimentin,SMA and ALK were measured in 93.3%,86.7%,and 31.8%of tumors,respectively,while the 81.8%of tumors were negative for S-100.Conclusions:In EPIMT,some specific pathological manifestations can be detected using CT and MRI.Typical features include the presence of a single isolated tumor,ill-defined borders,inflammatory infiltration,progressive and continuous enhancement or slow wash in and slow wash out,and the presence of lymph nodes around the tumor.Comparative analysis between pathology and imaging will be helpful in future to improve the diagnostic accuracy for types of EPIMT.