INTRADUCTAL EXTENSION OF PRIMARY INVASIVE BREAST-CARCINOMA TREATED BYBREAST-CONSERVATIVE SURGERY - COMPUTER GRAPHIC 3-DIMENSIONAL RECONSTRUCTION OF THE MAMMARY DUCT-LOBULAR SYSTEMS

Background. Intraductal tumor extension is a characteristic feature of primary breast carcinoma, and is an important consideration in patien ts undergoing breast conservative surgery. However, there have been no reports of studies of intraductal extension within the mammary ductal tree. Methods. Quadrantectomy specimens from 20 patients with primary invasive breast carcinoma were examined by subgross and stereomicrosc opic technique to visualize intraductal tumor extension. Serial 2 mm-t hick sections were subjected to two-dimensional (2-D) tumor mapping, m easuring the distances and angles of extension, and to three-dimension al (3-D) reconstruction of the mammary duct-lobular systems by means o f computer graphics. Results. Intraductal tumor extension was found in 16 of 20 specimens (80.0%), extending continuously from the primary i nvasive carcinoma through the mammary ductal tree. The distances and a ngles of extension were larger in tumors with microcalcifications, pap illotubular invasive ductal carcinoma, 30% or more of intraductal comp onent, and comedo-type intraductal tumor extension. The 3-D reconstruc tions demonstrated three types of extension; central(ll cases), periph eral (3 cases), and mixed (2 cases). Further, there were some ductal b ranches anastomosing with different mammary duct-lobular systems at va rious sites. In one specimen, intraductal tumor extended widely from t he primary invasive carcinoma through a branch connecting adjacent mam mary duct-lobular systems. Conclusions. Three-dimensional reconstructi on images of intraductal extension of invasive breast carcinomas are p resented for the first time to the authors' knowledge. Examples of duc tal anastomoses were observed, and should be considered as a risk fact or for possible widespread intraductal extension through multiple mamm ary duct-lobular systems.