Background: The intraductal spread of breast carcinoma can occur along the mammary ductal/lobular systems (MDLS) with no invasion of tissues. Because ductal anastomoses in the MDLS are considered to be a possible risk factor for extensive intraductal spread of breast carcinoma, the architecture of the MDLS has important therapeutic implications for patients treated with breast-conserving surgery.
Methods: An entire breast resected by subcutaneous mastectomy from a 69-year-old woman with ductal carcinoma in situ (DCIS) was examined in submacroscopic sections by stereomicroscopic and histologic techniques. Serial 2-mm sections underwent computer-assisted complete three-dimensional reconstruction of all MDLS.
Results: The entire breast that was studied contained 16 MDLS that were arranged radially, with the nipple at the center. Of these 16 MDLS, 4 (25.0%) had ductal anastomoses whereas the remaining 12 MDLS had no ductal anastomoses and completely independent regional anatomy. Ductal anastomoses were observed at 11 sites in the 4 MDLS. The 2 of 11 ductal anastomoses that connected different MDLS (18.2%) were situated > 4 cm from the nipple. The remaining nine ductal anastomoses connected ducts within the same MDLS; their location varied from near the nipple to the peripheral region. In the specimen examined, DCIS extended only within a single MDLS and did not spread between different MDLS via ductal anastomoses.
Conclusions: To the authors' knowledge, the current study is the first time the complete architecture of all MDLS in an entire breast has been studied three-dimensionally. The risk of promoting the intraductal spread of disease during surgery may be greater when intraductal lesions extend more peripherally than centrally. The features of ductal anastomoses may provide a significant anatomic clue regarding negative surgical margins in breast-conserving surgery.
Copyright 2001 American Cancer Society.