Rhabdomyosarcoma of the breast: a clinicopathologic study and review of the literature

　　乳腺的横纹肌肉瘤：临床研究和及文献复习

　　Abstract：Background Rhabdomyosarcoma (RMS) is an uncommon malignancy of the breast.The aim of this study was to summarize its clinico pathologic features and biological behavior.Methods Five primary or secondary breast RMSs were collected.Their clinicopathological characteristics and all published literature about breast RMS were reviewed.Immunohistochemical study of desmin,myogenic differentiation 1 (MyoD1),myogenin,leukocyte common antigen (LCA),vimentin,cytokeratin (AE1/AE3),E-cadherin,neuron specific enolase (NSE),CD99,chorioallantoic membrane 5.2 (CAM5.2) and epithelial membrane antigen (EMA) expression were performed.

　　Results The five patients were all female with ages ranging from 16 to 46 years old (mean,30 years).Three were metastatic breast RMSs,two embryonal and one solid variant alveolar,with the primary tumor sites the right labium majus,left nasal meatus and nasopharynx,respectively.The other two,one embryonal and one alveolar,were primaries.Grossly,the surgical specimens revealed round or oval,well-demarcated but nonencapsulated masses.Their cut surfaces consisted of homogeneous grayish yellow or white tissue.Microscopically,most tumor cells were poorly differentiated small round,oval or small polygons with eosinophilic cytoplasm.All cases were positive for vimentin,desmin,MyoD1 and myogenin.One embryonal RMS also had a few cells with perinuclear staining of AEI/AE3.The other markers were negative.Conclusions Although primary or metastatic RMS in breast was almost confined to young adolescent females,our cases suggested that it can also happen to the middle-aged women.Embryonal RMS has a certain metastatic potential.MyoD1 and myogenin are two useful markers when making differential diagnosis.Axillary lymph node status and age may play a role in the prognosis of primary breast RMS patients.

　　摘要：背景 ：乳腺横纹肌肉瘤是罕见的恶性肿瘤。目的：探讨乳腺横纹肌肉瘤的病理诊断及鉴别诊断。方法：观察5例乳腺横纹肌肉瘤的临床病理和复习相关文献,并采用Desmin、MyoD1、Myogenin、LCA、vimentin、AE1/AE3、E-cadherin、NSE、CD99、CAM5.2、EMA进行EnVision法免疫组化染色。

　　结果：五例女性患者 年龄从16岁到46岁。3例是发生转移的乳腺腺泡型横纹肌肉瘤，（原发部位是为右侧大阴唇、左鼻道和鼻咽部）2例原发部位胚胎型横纹肌肉瘤和1例腺泡型横纹肌肉瘤.其他两例都是原发，一例是胚胎型横纹肌肉瘤，一例是腺泡型横纹肌肉瘤。3例手术切片显示边界清楚无包膜的圆形或椭圆形肿物，组织切片呈均匀的黄色或白色。显微镜下，5例都显示分化不均匀小圆形或椭圆形，死酸性，细胞多边形。所有病例vimentin，desmin，MyoD1 ，myogenin呈阳性。一例腺泡型横纹肌肉瘤有少量核染色AEI/AE3。其他的标记物呈阴性。结论：所有原发的乳腺腺泡型横纹肌肉瘤发生于年轻女性，病例也显示它同样发与中年妇女。对于标记物诊断MyoD1 and myogenin非常有用。腋窝淋巴结和年龄在诊断原发乳腺横纹肌肉瘤 起重要作用。