Computer-assisted complete three-dimensional reconstruction of the mammary ductal/lobular systems: implications of ductal anastomoses for breast-conserving surgery.

Abstract

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. 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. 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. 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.