title: Escaping from Flatland: clinical and biological aspects of human mammary duct anatomy in three dimensions.
abstract: Accurate knowledge of breast duct anatomy in three dimensions is needed to understand normal breast development, how intraepithelial neoplasia may spread through a breast, and the potential for diagnostic and therapeutic access to breast parenchyma via the nipple. This paper reports three related exploratory studies. In study 1, the median number of milk-collecting ducts in the nipple was determined in 72 breasts excised for cancer; in study 2, the volumes of all 20 complete duct systems ("lobes") in an autopsy breast were measured from 2 mm serial "subgross" sections; and in study 3, a 3D digital model of all collecting ducts in a mastectomy nipple was made from 68 100 micro m serial sections. The mastectomy nipples contained 11-48 central ducts (median 27, inter-quartile range 21-30). In the autopsy breast, the largest "lobe" drained 23% of breast volume; half of the breast was drained by three ducts and 75% by the largest six. Conversely, eight small duct systems together accounted for only 1.6% of breast volume. The 3D model of the nipple revealed three distinct nipple duct populations. Seven ducts maintained a wide lumen up to the skin surface (population A); 20 ducts tapered to a minute lumen at their origin in the vicinity of skin appendages (population B) on the apex of the nipple; and a minor duct population (C) arose around the base of the papilla. Major variations in duct morphology and extent define highly variable territories in which intraepithelial neoplasia could grow. While population A ducts appear accessible to duct endoscopy or lavage, population B and population C ducts may be less accessible.
authors.affiliation: Department of Pathology, University of Glasgow, Glasgor Royal Infirmary, 84 Castle Street, Glasgow G4 0SF, Scotland, UK. going@udcf.gla.ac.uk
authors.forename: James J
authors.initials: JJ
authors.lastname: Going
authors.forename: David F
authors.initials: DF
authors.lastname: Moffat
mesh_terms: D001344:Autopsy; D001943:Breast Neoplasms / Q000473:pathology; D004724:Endoscopy; D005260:Female; D006801:Humans; D042361:Mammary Glands, Human / Q000033:anatomy & histology* / Q000473:pathology; D008408:Mastectomy; D008954:Models, Biological; D009558:Nipples / Q000033:anatomy & histology / Q000473:pathology; D007507:Therapeutic Irrigation