低度恶性肌纤维母细胞肉瘤的临床病理学观察

目的：探讨低度恶性肌纤维母细胞性肉瘤（low—grade myofibroblastic sarcoma，LGMS）的临床病理学特征、免疫学表型及鉴别诊断。方法：对2例发生于直肠系膜和1例发生于上颌窦的LGMS进行光镜观察和免疫组化标记，并对国内外文献进行复习。结果：光镜下，肿瘤细胞呈梭形，排列成束状或席纹状，核分裂像可见（3—4个／10HPF）。免疫组化染色结果示瘤细胞弥漫性广泛表达Vim，Des和SMA表达程度不一，但均不表达h—caldesmon、MSA、CD117、CD34、NSE、Mdanoma—pan、HMB45、ALK和S-100蛋白。结论：LGMS是一种少见的软组织肉瘤，发生于肠系膜和上颌窦的LGMS更是罕见。其组织学形态及免疫表型显示瘤细胞具有肌纤维母细胞性分化。诊断时应与胃肠间质瘤、纤维瘤病、纤维肉瘤和平滑肌肉瘤等相鉴别。

Clinicopathologic observation of low- grade myofibroblastic sarcoma

Objective ：To study the clinicopathologic, immunohistochemical features and diffential diagnosis of low -grade myofibroblastic sarcoma （LGMS）. Methods：Three cases of LGMS, including two cases from mesenterium, and one case from maxillary sinus,were investigated by light microscopy and immunohistochemistry. Moreover,the related literature was reviewed. Results： Microscopically, the tumor cells were spindle - shaped and arranged in fasciculus or whirlpool. The nuclei displayed mild to moderate atypia with mitotic figures counted 3 -4/10HPF. Immunohistochemically, the tumor cells were diffusely strong positive for Vim, and not uniform for Des and SMA, but negative for h - caldesmon, MSA, CD117, CD34, NSE, Melanoma - pan, HMB45, ALK, and S - 100 protein. Conclusion： LGMS is a rare entity of soft tissue tumors,most of which are of low -grade malignancy. It is extremely rare that LGMS occurs in mesenterium and maxillary sinus. The light microscopic and immunohistochemical features all favor a myofibroblastic differentiation. LGMS should be distinguished from gastrointestinal stromal tumor （ GIST）, fibromatosis ,fibmsarcoma, and leiomyosarcoma.