McCormick D, Mentzel T, Beham A, Fletcher C D
Department of Histopathology, St. Thomas Hospital, London, England.
Am J Surg Pathol. 1994 Dec;18(12):1213-23. doi: 10.1097/00000478-199412000-00004.
Dedifferentiated liposarcoma is uncommon, and only a small number of cases have been documented. We describe the clinicopathologic features in a series of 32 cases. All patients were adults (age range, 37-83 years; median, 67 years); 20 were men and 12 were women. Commonest site was the retroperitoneum (fifteen cases); six cases arose in the limbs, four in the paratesticular region, three in the peritoneal cavity, two on the trunk, and one each in the buttock and larynx. One primary tumor was subcutaneous. Thirty tumors arose de novo (i.e., combined with well-differentiated tumor in the primary lesion), while two developed in recurrences of a previously well-differentiated liposarcoma. The well-differentiated component was most often lipoma-like and typically there was a histologically abrupt transition to spindle celled nonlipogenic tumor. The dedifferentiated component most often resembled either storiform "malignant fibrous histiocytoma" ("MFH") with limited pleomorphism or myxofibrosarcoma (myxoid "MFH"); the latter pattern is rarely otherwise seen in the retroperitoneum. A small number of cases showed appearances reminiscent of myxoid embryonal rhabdomyosarcoma. An unusual feature in three cases was the occurrence of a discontinuous micronodular pattern of dedifferentiation. Average follow-up of 5.6 years (range, 3 months to 33 years) in 27 cases have revealed local recurrence in 14 patients and systemic metastases in only four patients. The primary sites of the metastasising cases were upper back, thigh, retroperitoneum, and paratesticular region. There have been only seven tumor-related deaths. Good prognosis in de novo dedifferentiated liposarcomas seems unrelated to the extent or morphologic pattern of dedifferentiation. However, high mitotic activity in the dedifferentiated component was associated with a more aggressive clinical course. Our study underlines that dedifferentiation in peripherally located or even subcutaneous liposarcomas does occur, albeit rarely, and that dedifferentiated liposarcomas of the limbs may metastasize. The results suggest that dedifferentiated liposarcomas, as a subgroup among the "MFH-like" sarcomas, have a better prognosis than pleomorphic sarcomas as a whole.
去分化脂肪肉瘤并不常见，仅有少数病例被记录。我们描述了一系列32例病例的临床病理特征。所有患者均为成年人（年龄范围37 - 83岁；中位数67岁）；男性20例，女性12例。最常见的部位是腹膜后（15例）；6例发生于四肢，4例发生于睾丸旁区域，3例发生于腹腔，2例发生于躯干，臀部和喉部各1例。1例原发肿瘤位于皮下。30例肿瘤为新发（即原发灶中合并有高分化肿瘤），2例由先前高分化脂肪肉瘤复发演变而来。高分化成分最常见为脂肪瘤样，通常在组织学上与梭形细胞非脂肪生成性肿瘤有突然转变。去分化成分最常类似伴有有限多形性的席纹状“恶性纤维组织细胞瘤”（“MFH”）或黏液纤维肉瘤（黏液样“MFH”）；后一种模式在腹膜后很少见。少数病例表现类似黏液样胚胎性横纹肌肉瘤。3例的一个不寻常特征是出现不连续的微结节状去分化模式。27例患者平均随访5.6年（范围3个月至33年），发现14例患者局部复发，仅4例患者发生全身转移。发生转移病例的原发部位为上背部、大腿、腹膜后和睾丸旁区域。仅有7例与肿瘤相关的死亡。新发去分化脂肪肉瘤的良好预后似乎与去分化的程度或形态模式无关。然而，去分化成分中高有丝分裂活性与更具侵袭性的临床病程相关。我们的研究强调，外周部位甚至皮下脂肪肉瘤确实会发生去分化，尽管很少见，且肢体去分化脂肪肉瘤可能发生转移。结果表明，去分化脂肪肉瘤作为“MFH样”肉瘤中的一个亚组，总体预后比多形性肉瘤要好。
