肌纤维瘤／肌纤维瘤病九例临床病理学分析

Myofibroma/myofibromatosis： a clinicopathologic analysis of 9 cases

目的 探讨肌纤维瘤/肌纤维瘤病的临床及病理组织学特征、诊断和鉴别诊断.方法回顾性分析2011年8月至2016年11月就诊于南京大学医学院附属鼓楼医院（7例）及会诊病例（2例）共9例肌纤维瘤/肌纤维瘤病患者的临床、病理资料及免疫表型特点,7例进行PDGFRB基因外显子第12、14号突变检测,4例应用荧光原位杂交（FISH）检测ETV6-NTRK3融合基因,同时复习相关文献.结果 患者男性7例,女性2例.发病年龄3 d至18岁,平均年龄5岁.发病部位：头面部8例,躯干部1例.临床表现多为局部境界清楚的肿块.组织学上,肿瘤可出现浅染区及深染区的双相结构.浅染区由具有嗜酸性胞质的胖梭形细胞构成,肿瘤细胞排列呈结节状、短束状或旋涡状.高倍镜下,细胞核呈细长的圆锥形或雪茄形,并缺乏核异型性.间质可发生程度不同的透明变性.深染区由原始的多边形或圆形的细胞核深染的细胞组成,细胞质淡染,细胞边缘较模糊,有时可见血管外皮瘤样结构,核分裂象可见.免疫组织化学显示：肿瘤浅染区细胞表达波形蛋白和平滑肌肌动蛋白（SMA）弥漫阳性;深染区原始间叶细胞表达波形蛋白弥漫阳性,SMA灶性区弱阳性;肿瘤表达结蛋白、S-100蛋白、h-Caldesmon、CD34、STAT6阴性.PDGFRB基因第12、14号外显子突变检测结果显示：2例伴有第12号外显子点突变c.1681C〉T（p.R561C）,1例伴有第14号外显子点突变c.1998C〉G（p.N666K）.4例3岁以下病例FISH检测ETV6-NTRK3融合基因显示阴性.9例均行外科单纯切除术,术后随访6~68个月,2例复发.结论 肌纤维瘤/肌纤维瘤病常发生于2岁以下的婴幼儿,形态学上肿瘤可出现浅染区及深染区的双相结构,分子遗传学可出现PDGFRB外显子突变,可作为疑难病例的辅助诊断指标.

Objective To investigate the clinical and histological features, diagnosis and differential diagnosis of myofibroma/myofibromatosis. Methods The clinical data and pathology features of nine cases of myofibroma/myofibromatosis were collected from August 2011 to November 2016 in Affiliated Drum Tower Hospital,Nanjing University Medical School and Children＇s Hospital of Nanjing Medical University. Immunohistochemistry（IHC）,PDGFRB molecular analysis and ETV6-NTRK3 gene fusion were performed and relevant literature reviewed. Results There were 7 males and 2 females, with age ranging from 3 days to 18 years（mean 5 years）. The tumors were located in head and neck（eight cases）and trunk （one case）. Clinically, the tumors presented as freely movable nodules. Microscopically, they appeared biphasic with alternating light- and dark-staining areas. The light-staining area consisted mainly of plump myoid spindle cells with eosinophilic cytoplasm arranged in nodules, short fascicles, or whorls.The dark-staining area was composed of round or polygonal cells with slightly hyperchromatic nuclei or small spindle cells arranged around a distinct hemangiopericytoma-like vascular pattern. IHC showed the tumor cells in the light-staining area were strongly positive for vimentin and SMA, while cells in dark-staining area were strongly positive for vimentin,and weakly for SMA. Tumor cells were negative for desmin, S-100 protein, h-Caldesmon,CD34 and STAT6. Analysis of PDGFRB mutations was performed in seven cases. Two cases showed 12 exon point mutation c.1681 c〉T（p.R561C）,one case showed 14 exon point mutation c.1998C〉G（p.N666K）. ETV6-NTRK3 gene fusion was not detected by fluorescence in situ hybridization in four patients under three years old. All cases were followed for 6 to 68 months,with two recurrences.Conclusions Myofibroma/myofibromatosis is an uncommon benign myofibroblastic tumor of infancy and childhood. The tumor can appear biphasic,and may show PDGFRB point mutation which is of potential diagnostic value.