Structure, Functional Changes, and Proliferative Pathology of the Human Mammary Lobule in Cancerous Breasts2

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Abstract
The mammary glandular tree of 50 human female breasts removed for clinical cancer by radical mastectomy was studied by subgross analysis in whole thin slices, a method that allowed a three-dimensional appraisal of the glandular structures, with removal of interesting or suspicious changes for histology. The glandular tree was more often atrophic (70%) than “adenosic” (rich in mammary lobules, 30%). Many physiopathologic changes were observed, mainly in the lobular area. Abnormal lobules were categorized by type on the basis of size, sensitivity to hormones, stroma, architecture, pattern of epithelial proliferation, cell type, and cell grading. The functional and minor lobular changes (atrophic, sclerotic, hyperplastic, and cystic) were frequent and, as expected, unevenly distributed between adenosic and atrophic breasts. The proliferative lobular changes (including atypical lobules with epithelial proliferation and metaplastic or apocrine lobules with epithelial proliferation) were also frequent but evenly distributed in adenosic (51%) or atrophic (46%) breasts. Intrinsic or extrinsic epithelial proliferation often caused unfolding or lengthening of the lobular structures with deviation of lobular architecture toward ductlike formations. The cells of proliferative changes ranged from typical cells to the anaplastic cells of in situ carcinomas. Independent microscopic foci of infiltrating cancer were found in 20% of either adenosic or atrophic breasts.