33例恶性纤维组织细胞瘤病理学重新诊断评估

目的:采用新版WHO软组织肿瘤分类对过去诊断的33例恶性纤维组织细胞瘤(malignant fibrous histio-cytoma,MFH)进行再评估,并对重新诊断的MFH/UPS(undifferentiated pleomorphic sarcoma,未分化多形性肉瘤)临床病理特点、组织学来源及分化方向进行了初步探讨.方法:参照新标准对过去诊断的33例MFH重新进行组织学观察,采用组织芯片及免疫组织化学方法,抗体选用神经特异性、肌特异性、脂肪等特异或相对特异性标记组合.由3位病理医生重新阅片,并结合免疫组织化学结果独立诊断.结果:3例MFH中,黏液性纤维肉瘤5例,平滑肌肉瘤5例,恶性外周神经鞘瘤3例,纤维肉瘤、炎性肌纤维母细胞瘤、骨巨细胞瘤及血管瘤样纤维组织细胞瘤各l例;其余16例(48.5%)可诊断为MFH/UPS.MFH/UPS多见于中老年(中位年龄63岁,38～76岁),中位最大径6.0 cm(3.0～14.0 cm),8例(50%)位于下肢者中有5例(31.3%)位于大腿.组织学上呈明显多形性.免疫组织化学结果,16例MFH/UPS(100%)均呈Vimentin强阳性,8例(50%)不同程度表达Muscle-specific actin,1例Desmin灶性阳性;11例(68.8%)肿瘤细胞不同程度表达CD68(KP1),7例(43.8%)表达CD68(PG-M1),与平滑肌肉瘤、恶性外周神经鞘瘤及脂肪肉瘤相比,差异有统计学意义;肿瘤细胞Ki67表达率为10%-100%,其中50%以上有14例,70%以上11例;2例(12.5%)P53阳性.结论:FH/UPS组织学上呈多形性,诊断时需排除其他多形性肉瘤,尤其是肌源性和神经源性肉瘤.免疫标记MFH/UPS表达Vimentin,部分表达肌源性标记和CD68.提示肿瘤可能来源于原始间叶细胞,部分显示纤维母细胞及肌纤维母细胞特征,并仍显示一定组织细胞标记.MFH/UPS仍具备一定临床病理特征.

Reassessment of the pathological diagnosis in 33 cases of malignant fibrous histiocytoma

OBJECTIVE:Since malignant fibrous histiocytoma (MFH) may be taken as an undifferentiajted pleomorphic sarcoma (UPS), this study was conducted to reassess 33 previously diagnosed MFH cases in the past 10 years based on the latest WHO concept. And then to search for the clinicopathological features, probably tumorigenesis, and the line of differentiation of the remaining MFH/UPS cases.METHODS: Thirty-three cases in tissue microarray were studied by immunohistochemistry with panels of neurogenic, myogenic, and lipogenic antibodies. Three expertise pathologists reevaluated the slides separately. RESULTS: Among the 33 cases, 17 cases (51.5%) of MFH had their diagnoses changed, including 5 leiomyosarcomas, 3 malignant peripheral nerve sheath tumors, 1 fibrosarcoma, 1 inflammatory myofibrosarcoma, 1 giant cell tumor and 1 angiomatoid fibrous histiocytoma. The remaining 16 cases (48.5%) were finally diagnosed as MFH/UPS, among which patients were mainly old adults (median age: 63 years; range: 38 to 76 years). The median tumor size was 6.0 cm (range: 3.0 to 14.0 cm), 8 cases (50%) located in lower limb and 5 cases (31.3%) located in thigh. These tumors had marked cytological and nuclear pleomorphism. Immunohistochemistry showed that Vimentin was strongly positive in all 16 MFH/UPS (100%), Muscle-specific actin was variously positive in 8 cases (50%) and 1 case focally expressed Desmin. Eleven cases (68.8%) variously expressed CD68 (KP1) and 7 cases (43.8%) expressed CD68 (PG-M1), which were much higher than leiomyosarcoma, malignant peripheral nerve sheath tumor and liposarcoma with significant difference. Moreover, Ki67 expression rates were from 10% to 100%, including 14 cases more than 50% and 11 cases more than 70%. However, only 2 cases (12.5%) showed P53 positive. CONCLUSION: MFH/UPS often show marked histological pleomorphism, and the diagnosis must be made by exclusion of other definitive sarcomas, especially myogenic and neurogenic sarcoma. Only Vimentin was always expressed in MFH/UPS, while some of the tumors were positive for myogenic antigen and CD68. It was suggested that MFH/UPS might arise from primary mesenchymal cells, and some cases exhibited fibroblastic and/or myofibroblastic features. In addition, histiocytic phenotypic marker did have more expression in MFH/UPS than in other sarcomas. MFH/UPS still had certain clinicopathological characteristics.