Source:http://linkedlifedata.com/resource/umls/id/C1510795
NCI: A usually benign neoplasm arising from the breast. It is characterized by the proliferation of cells with myoepithelial differentiation around spaces which are lined by epithelial cells. Rarely, the epithelial and/or myoepithelial cells may undergo malignant transformation. Cases with malignant transformation may follow an aggressive clinical course, including recurrences and local and distant metastases.