Objective: To investigate the clinicopathological characteristics and differential diagnosis of lipofibromatosis. Methods: The clinicopathological features and immunohistochemical profiles in 8 cases of lipofibromatosis diagnosed at Fudan University Shanghai Cancer Center from January 2008 to June 2017 were studied. Molecular analysis of β-catenin mutation by Sanger sequencing, NTKR1 and ETV6 rearrangements by FISH were performed. The follow up information was evaluated and the literature was reviewed. Results: There were 4 males and 4 females with a median age of 1.5 years at presentation (range, 3 months-9 years). Tumor arose in the hand (4 cases), foot (2 cases) and trunk (2 cases), manifesting as a painless subcutaneous mass. Two cases were congenital, one with tumor noted at birth and the others shortly after birth. Grossly, the tumors were poorly defined and irregularly shaped, composed predominantly of fatty tissue which was mingled with fibrous element. They ranged from 1 to 5 cm in size (mean, 2.6 cm). Microscopically, they were characterized by variably sized lobules of adipose tissue traversed by fascicles, bundles or trabeculae of proliferative fibroblasts and myofibroblasts, resembling desmoid tumor. In 2 cases, the tumor infiltrated adjacent skeletal muscles. On high power, the spindled fibroblasts and myofibroblasts had a bland appearance with very low mitotic activity (<1/10 HPF). By immunohistochemistry, they showed variable staining of α-SMA, MSA, CD34 and CD99, with negativity for β-catenin, desmin, h-CALD, EMA, ALK, and S-100 protein. Ki-67 index was low (<2%). Molecular analysis showed no mutation of β-catenin gene (0/3), no NTRK1 gene rearrangement (0/3) and no ETV6 gene rearrangement (0/2). Follow up information was available in 6 patients, revealed local recurrence in two and persistent disease in one. Conclusions: Lipofibromatosis is a special variant of infantile fibromatosis, which has a predilection for the distal portion of the extremities of neonates and infants and characterized by lobules of adipose tissue traversed by demoid tumor-like fibroblasts and myofibroblasts. However, it differs from desmoid tumor by harboring no mutation of β-catenin gene. Familarity with its clinicopathological characteristics helps the distinction from its morphological mimics.
目的：探讨脂肪纤维瘤病的临床病理学特征、诊断和鉴别诊断。 方法：回顾性分析复旦大学附属肿瘤医院病理科2008年1月至2017年6月8例脂肪纤维瘤病会诊病例的临床病理学资料和免疫表型，采用Sanger测序法检测β－catenin基因突变，运用荧光原位杂交法检测NTRK1和ETV6基因重排，分析随访结果并复习文献。 结果：男性4例，女性4例，年龄3个月至9岁(中位年龄1.5岁)。肿瘤分别发生于手(4例)、足(2例)和躯干(2例)，表现为局部缓慢性生长的无痛性肿块，境界不清。2例为先天性，其中1例出生时即发现患病，1例于出生后不久发现。大体上，肿瘤外形不规则，由灰黄色脂肪组织和混杂的灰白色纤维组织组成，平均直径2.6 cm(范围1～5 cm)。镜下观察：肿瘤含有大量的脂肪组织，略呈分叶状，脂肪组织间隔内可见条束状或梁状增生的纤维母细胞和肌纤维母细胞，类似韧带样瘤型纤维瘤病，2例浸润邻近的骨骼肌。增生的纤维母细胞和肌纤维母细胞无明显的异型性，核分裂象罕见(<1/10 HPF)。纤维母细胞和肌纤维母细胞程度不等表达平滑肌肌动蛋白、肌特异性肌动蛋白、CD34和CD99，不表达β－catenin、结蛋白和S－100蛋白等标志物，Ki－67阳性指数<2%。分子检测显示无β－catenin基因突变(0/3)，无NTRK1基因重排(0/3)和ETV6基因重排(0/2)。随访6例，2例局部复发，1例带瘤生存。 结论：脂肪纤维瘤病好发于新生儿和婴幼儿四肢末端，以大量脂肪组织和穿插其间类似韧带样瘤型纤维瘤病的纤维母细胞和肌纤维母细胞条束为特征，但与韧带样瘤型纤维瘤病不同，不涉及β－catenin基因突变。熟悉其临床病理学特征有助于与具有相似形态的间叶性肿瘤相鉴别。.
Keywords: Beta catenin; Fibroma; Immunohistochemistry; In situ hybridization, fluorescence.