甲状腺未分化癌很少见,按世界卫生组织分类,可将其分为梭形细胞型、巨细胞型及小细胞型三种。除第三型外其余两型之预后较差,Meissner 甲状腺肿瘤一书中在巨细胞癌名称下将梭形细胞癌、癌肉瘤并列为同义词,此癌恶性程度较大,梭形细胞来源历来有上皮源性及间叶源性两种争论。本文报告一例在良性腺瘤基础上恶变的梭形细胞癌,并结合文献讨论其来源。 Undifferentiated thyroid cancer is rare. According to the classification of the World Health Organization, it can be classified into three types: spindle cell type, giant cell type, and small cell type. In addition to the third type, the prognosis of the other two types is poor. In the book Meissner Thyroid Neoplasms, fusiform cell carcinoma and carcinosarcoma are listed as synonymous under the name of giant cell carcinoma. The degree of malignancy of this cancer is relatively large, and the spindle cells have a long history. Epidermis-derived and mesenchymal-originated arguments. This article reports one case of a fusiform cell carcinoma that is malignant on the basis of benign adenoma, and discusses its source in combination with literature.