Pattern of distribution of intraductal and infiltrating ductal carcinoma: a three-dimensional study using serial coronal giant sections of the breast.

The purpose of this study was to establish the 3-dimensional (3D) structure of the breast tissue and to study the distribution and relationship between the intraductal and infiltrating components of ductal carcinoma and other proliferative epithelial lesions of the breast. Thirty mastectomy specimens with infiltrating carcinoma less than 3.0 cm in diameter were serially cut in the coronal plane. Each giant section was divided into small sections for routine processing. Using Photoshop (Adobe) and PowerPoint (Microsoft) software programs, the routinely stained sections were scanned and assembled to reestablish complete giant sections of the breast and subsequently the 3D structure. Intraductal and infiltrating ductal carcinomas, epithelial hyperplasia with atypia, and marked epithelial hyperplasia without atypia were mostly confined to a single duct (27 cases), resulting in an increase in size of the involved breast segment. Three remaining cases included a case of Paget's disease with tumor appearing to spread from one duct system to another system through the epidermis and two cases with multiple separate foci of carcinomas located in different quadrants and accompanied by ductal spread in different lactiferous ducts. Both intraductal and infiltrating carcinomas were often located in the superficial segments (near the subcutaneous tissue) (28 cases). The infiltrating components were often located adjacent to area of pure intraductal carcinoma and were often peripheral (nearer the chest wall than the nipple). Intraductal carcinomas showed a "fanned out" pattern of distribution, frequently extended toward the nipple (with involvement of the nipple or subareolar tissue in 7 cases), and occasionally were seen in the breast tissue peripheral to the infiltrating carcinoma. Multiple ducts with intraductal carcinoma could be seen to be connected with each other with serial sections. However, in at least 6 cases, foci of intraductal carcinomas were separated from each other by segments of duct with benign epithelium. Breast carcinoma often arise from the breast segment close to the subcutaneous tissue. Infiltrating carcinoma lesser than 3.0 cm in diameter is usually located adjacent to the area of pure intraductal. The pattern of spread of intraductal carcinoma has a pyramid-like shape, with the summit toward and occasionally extending up to the nipple. These findings should be considered in the surgical strategy for segmental resections of breast carcinomas.