伴有脑膜上皮细胞样旋涡状特征的去分化脂肪肉瘤六例临床病理学观察

Clinicopathological features of dedifferentiated liposarcomas with meningothelial-like whorls: report of six cases

目的探讨伴有脑膜上皮细胞样旋涡特征的去分化脂肪肉瘤(dedifferentiated liposarcomas with meningothelial-like whorls,DDLMW)的组织形态学、免疫组织化学及分子遗传学特征。方法收集江苏省人民医院(南京医科大学第一附属医院)2012年3月至2018年8月诊断为DDLMW的患者6例病历资料及存档切片,采用免疫组织化学染色检测MDM2、CDK4、p16等,应用荧光原位杂交(FISH)法检测MDM2基因扩增情况,并复习相关文献。结果患者男性3例,女性3例;4例发生于后腹膜,2例发生于纵隔,发病年龄范围40~77岁(中位年龄58岁)。大体表现为巨大单发或多发结节状肿块,镜下除了可见高分化脂肪肉瘤成分之外,均可见具有特征性的旋涡样结构,形态类似脑膜瘤;旋涡小体肿瘤细胞梭形或卵圆形,同心圆状致密排列,轻-中度异型性;此外,4例在旋涡小体的周围或中间可见化生性骨组织。免疫表型:肿瘤组织表达MDM2、CDK4、p16,不表达S-100蛋白、平滑肌肌动蛋白、SOX10、上皮细胞膜抗原、CD21、CD23、CD35;肿瘤细胞Ki-67阳性指数低。6例经FISH检测均显示肿瘤细胞伴有MDM2基因的扩增。结论DDLMW是一种罕见的去分化脂肪肉瘤的组织学亚型,特征性的旋涡状结构并不预示其有神经束膜或滤泡树突细胞的分化,认识并熟悉其存在结合免疫组织化学及MDM2基因FISH检测有助于其诊断与鉴别诊断。

Objective To investigate the histopathologic,immunohistochemical,molecular genetic characteristics of dedifferentiated liposarcomas with meningothelial-like whorls(DDLMW).Methods Six cases of DDLMW diagnosed at Jiangsu Province Hospital(the First Affiliated Hospital of Nanjing Medical University)from March 2012 to August 2018 were enrolled.The cases were analyzed by routine HE staining,immunohistochemistry(MDM2,CDK4 and p16)and fluorescent in-situ hybridization(FISH)on MDM2 gene.Related literatures were also reviewed.Results Three of the 6 patients were male.The patient ages ranged from 40 to 77 years(mean,58 years).Four tumors occurred in the retroperitoneum and two in the mediastinum.Histologically,the tumors showed,in addition to foci of well-differentied liposarcoma,characteristic,scattered meningothelial-like concentrical whorls.The whorls were composed of tightly,concentrically arranged,spindle to ovoid cells with mild to mederate cytological atypia.Metaplastic bone was present within or in their immediate vicinity in four case.The tumors cell also showed strong and diffuse immunoreactivity to MDM2,CDK4 and p16,but no immunoreactivity to S-100 protein,SMA,SOX10,EMA,CD21,CD23 or CD35.The Ki-67 labeling indexes were low,while FISH showed high levels of MDM2 amplification in all cases.Conclusions DDLMW is a rare morphologic variant of dedifferentiated liposarcoma.The whorls in DDLMW do not represent perineurial or follicular dendritic differentiation.Recognition and familiarity with its existence,as well as combined application of immunohistochemical staining and MDM FISH,are important to avoid confusion with other lesions.