A neoplastic process that arises from the terminal ductal lobular unit of the breast parenchyma. It is usually solitary and confined to a single lobular unit. It is characterized by the presence of a monomorphic epithelial proliferation in a cribriform, micropapillary, or solid growth pattern. Focal architectural features of low grade ductal carcinoma in situ are present. There is an increased risk for development of invasive breast carcinoma. [from
NCI]