逆分化软骨肉瘤(dedifferentiated chondrosarcoma)是一种软骨肉瘤的少见变异。占软骨肉瘤的10%以下。对于这种肿瘤的来源有两种意见,一是认为直接从软骨肿瘤转变而来;另一种认为是低度恶性的软骨部分和高度恶性的逆分化部分共存。作者回顾了男25例,女21例。年龄21～83岁,分为二组。第一组21例,7例大于50岁。组织学上为低恶性度的软骨肉瘤(Broders标准为Ⅰ级),第二组25例,17例大于50岁。组织学上为高恶性度软骨肉瘤(Broders标准为Ⅱ级或Ⅲ级)。X线表现可分为三型。Ⅰ型:骨的皮质轮廓无变形、没有皮质增厚,也没有骨膜反应;有钙化型密度增 Dedifferentiated chondrosarcoma (dedifferentiated chondrosarcoma) is a rare variant of chondrosarcoma. It accounts for less than 10% of chondrosarcoma. There are two opinions on the origin of this type of tumor. One is that it is directly converted from a cartilage tumor; the other is considered to be the coexistence of a low-grade cartilage portion and a highly malignant degenerative portion. The author reviewed 25 males and 21 females. Age 21 to 83 years, divided into two groups. The first group of 21 cases, 7 cases are more than 50 years old. Histologically low-grade chondrosarcoma (Broders criteria for grade I), the second group of 25 cases, 17 cases greater than 50 years of age. Histologically high grade chondrosarcoma (Broders standard class II or III). X-ray performance can be divided into three types. Type I: No cortical contour of the bone, no cortical thickening, no periosteal reaction; increased calcification type density