Henricks W H, Chu Y C, Goldblum J R, Weiss S W
The University of Michigan Hospital, Ann Arbor 48109-0054, USA.
Am J Surg Pathol. 1997 Mar;21(3):271-81. doi: 10.1097/00000478-199703000-00002.
We studied 155 cases of dedifferentiated liposarcoma to define its clinicopathologic features and behavior, in particular how the extent and grade of dedifferentiation affected outcome. Tumors occurred in late adult life (median, 61.5 years: range, 21-92 years), most commonly in the retroperitoneum (106 cases), extremities and trunk (32 cases), and scrotum/spermatic cord (13 cases). The majority of dedifferentiated liposarcomas presented as de novo lesions, whereas the remainder developed as a late complication of a preexisting well-differentiated liposarcoma after an average interval of 7.7 years. At the time of presentation, most of the dedifferentiated liposarcomas displayed extensive areas of high-grade dedifferentiation resembling malignant fibrous histiocytoma or high-grade fibrosarcoma, whereas a minority contained only areas of low-grade dedifferentiation resembling fibromatosis or well-differentiated fibrosarcoma. Divergent myosarcomatous or osteosarcomatous differentiation was observed focally in six cases. The behavior of dedifferentiated liposarcomas was that of a high-grade sarcoma with a local recurrence rate of 41%, a metastatic rate of 17%, and disease-related mortality of 28%. The most important prognostic factor was location in that retroperitoneal tumors had significantly worse survival than those in other sites. Tumors were divided into those having less than or those with more than 25% dedifferentiation, and dedifferentiated zones were classified into low grade or high grade. Neither low-grade dedifferentiation nor a low percentage of dedifferentiation was associated with an improved outcome for the tumors examined in this study; however, in no cases was the absolute size of the dedifferentiated focus <2 cm. Therefore, this study did not determine a minimum, or threshold, amount of dedifferentiation below which outcome was more favorable. The behavior of liposarcomas in which the dedifferentiated component was entirely low grade was more similar to that of traditional dedifferentiated liposarcoma than to that of well-dedifferentiated liposarcoma. Our study supports the expansion of the definition of dedifferentiated liposarcoma to include tumors with low-grade dedifferentiation and also suggests that low-grade dedifferentiation represents a precursor lesion of high-grade dedifferentiation.
我们研究了155例去分化脂肪肉瘤，以明确其临床病理特征及生物学行为，尤其是去分化的范围和分级如何影响预后。肿瘤发生于成年晚期（中位年龄61.5岁，范围21 - 92岁），最常见于腹膜后（106例）、四肢和躯干（32例）以及阴囊/精索（13例）。大多数去分化脂肪肉瘤表现为原发性病变，其余则是在平均7.7年的间隔后，由先前存在的高分化脂肪肉瘤发展而来的晚期并发症。在初诊时，大多数去分化脂肪肉瘤显示出广泛的高级别去分化区域，类似于恶性纤维组织细胞瘤或高级别纤维肉瘤，而少数仅含有低级别去分化区域，类似于纤维瘤病或高分化纤维肉瘤。6例可见局灶性异源性肌肉瘤或骨肉瘤分化。去分化脂肪肉瘤的生物学行为表现为高级别肉瘤，局部复发率为41%，转移率为17%，疾病相关死亡率为28%。最重要的预后因素是肿瘤位置，腹膜后肿瘤的生存率明显低于其他部位的肿瘤。肿瘤被分为去分化程度小于或大于25%的两类，去分化区域分为低级别或高级别。在本研究中，低级别去分化和低去分化比例均与肿瘤预后改善无关；然而，去分化灶的绝对大小均未<2 cm。因此，本研究未确定一个去分化的最低或阈值量，低于此量预后更有利。去分化成分完全为低级别脂肪肉瘤的生物学行为与传统去分化脂肪肉瘤更为相似，而非与高分化脂肪肉瘤相似。我们的研究支持扩大去分化脂肪肉瘤的定义，将低级别去分化的肿瘤纳入其中，同时也表明低级别去分化是高级别去分化的前驱病变。
