伴有肌样/肌纤维母细胞性分化的隆突性皮纤维肉瘤的临床病理分析

目的 探讨隆突性皮纤维肉瘤（ＤＦＳＰ）中肌样／肌纤维母细胞性分化的本质及其临床病理学意义。方法 采用常规ＨＥ切片对１２４例ＤＦＳＰ进行筛选,对6例伴有肌样／肌纤维母细胞性分化的ＤＦＳＰ病例进行免疫组织化学标记,其中２例加做电镜检测。结果 肌样／肌纤维母细胞性分化多出现在纤维肉瘤型ＤＦＳＰ（ＦＳ－ＤＦＳＰ）中,表现为肿瘤周边部或肿瘤内散在性分布的深嗜伊红色小结节或短要束,由梭形细胞组成,细胞多无异型性,核分裂象也罕见,形态上似平滑肌细胞或肌纤维母细胞。免疫组织化学标记显示肌样区域细胞表达α－平滑肌肌动蛋白和肌物质特异性肌动抗原,不表达ＣＤ３４;电镜观察证实细胞含有质膜下微丝束、局灶性致密体及微胸饮囊泡样结构,与肌纤维母细胞相一致,结论 ＤＦＳＰ中的肌样／肌纤维母细胞性分化可能是间质中肌纤维母细胞增生的结果,并非代表了瘤细胞的真性肌纤维母细胞性分化。

Myoid/myofibroblastic differentiation in dermatofibrosarcoma protuberans: a clinicopathologic study of six cases

OBJECTIVE: The nature of myoid/myofibroblastic differentiation in dermatofibrosarcoma protuberans (DFSP) and its clinical and pathological significance were studied. METHODS: 124 DFSPs were reviewed by light microscopy. 6 cases with areas of myoid/myofibroblastic differentiation were assayed with immunohistochemical technique and electron microscopy was applied in two cases. RESULTS: Myoid/myofibroblastic differentiation occurred most commonly in fibrosarcomatous DFSP (FS-DFSP). It was recognized histologically as peripherally distributed or randomly scattered small eosinophilic nodules or short bundles, which were composed of bland spindle cells, closely resembling smooth muscle cells or myofibroblasts. Immunohistochemically, cells in myoid/myofibroblastic areas showed positive staining for alpha-SMA, MSA and vimentin, but negative for desmin and CD34. Electron microscopic study displayed the presence of microfilament bundles, focal dense bodies and micropinocytic vesicles, consistent with those of myofibroblasts. CONCLUSION: Myoid/myofibroblastic areas in DFSP possibly represents the hyperplasia of stromal myofibroblasts, rather than true myofibroblastic differentiation of the neoplastic cells.