肢体去分化脂肪肉瘤临床病理学分析

Dedifferentiated liposarcoma of extremities： a clinicopathologic analysis

目的探讨肢体去分化脂肪肉瘤的临床病理特征、诊断及鉴别诊断。方法收集2009至2017年就诊于北京积水潭医院的9例去分化脂肪肉瘤临床及影像学资料，行光镜观察和EnVision二步法免疫组织化学染色，采用荧光原位杂交法检测MDM2基因扩增情况，并复习相关文献。结果9例去分化脂肪肉瘤，患者年龄61-79岁，平均68岁。女性6例，男性3例。发生于大腿6例，小腿2例，臀部1例。组织学上均存在经典的高分化脂肪肉瘤结构，去分化成分中5例为高级别未分化肉瘤，其中1例伴有上皮样分化，1例为低级别纤维肉瘤，1例为中度恶性黏液纤维肉瘤，2例为硬化性上皮样纤维肉瘤。高级别去分化肉瘤中可伴有低级别的组织形态。去分化成分与高分化成分间可界限清楚，为分离的多结节，也可二者相互移行或混杂存在。可存在同源性去分化及异源性成分。免疫组织化学显示波形蛋白、p16、CDK4阳性，6例（6/9）表达MDM2，1例（1/9）p53阳性，1例（1/9）伴有上皮样分化的广谱细胞角蛋白阳性，S-100蛋白在高分化脂肪肉瘤成分中阳性表达。6例（6/9）存在MDM2基因扩增。结论肢体去分化脂肪肉瘤较少见，MDM2基因扩增的MDM2/CEP12比值较腹膜后去分化脂肪肉瘤低，可出现多倍体。组织形态多样，其中的梭形细胞低级别去分化需要与梭形细胞脂肪肉瘤鉴别，伴有上皮样分化时要与转移癌等鉴别。

Objective To study the clinicopathologic features of dedifferentiated liposarcoma of extremities. Methods Nine cases of dedifferentiated liposarcoma of extremities diagnosed at Beijing Jishuitan Hospital from 2009 to 2017 were selected. The histological features of cases of dedifferentiated liposarcoma of extremities were evaluated by HE and immunohistochemistry, together with the clinical and radiological features. Floureseence in situ hybridization （FISH） was used to detect MDM2 amplification. Results They were located in the thigh （6 cases） , calf （2 cases） and buttock （1 case）. There were six females and three males. Patients＇ age ranged from 61 to 79 years （mean 68 years）. Histologically, there were two components, well-differentiated liposarcoma and dedifferentiated sarcoma with or without transitional lesions between them. The histology of dedifferentiated liposarcoma included undifferentiated sarcoma and fibrosarcoma. Heterologous elements such as bone and cartilage were present in two cases. Immunohistochemieal study showed the tumor cells expressed vimentin, CDK4 and pl6. MDM2 were positive in 6 cases （6/9） and p53 was positive in one case（ 1/9）. CKpan was positive in the epithelioid differentiation area. S-100 protein was positive in the well-differentiated liposareoma component. FISH showed the amplification of MDM2（6/9）. Conclusions Dedifferentiated liposarcoma of extremities is very rare. The diagnosis should be combined with the histological characteristics and immunohistochemical results and differentiated from the other tumors and tumor-like lesions.