A new method of complete peripheral margin assessment in breast conservative surgery using an adjustable polygonal prism mould

Conventional margin evaluation for breast conservative surgery is usually based on the sections taken perpendicular to the inked margins and has difficulty in completeness. We have developed a new method using an adjustable mould during fixation so that the three-dimensional specimen is fixed in the shape of polygonal prism. The new method enables us to assess peripheral margins completely by examining the inner surfaces of the marginal slices cut parallel to the flat peripheral margins of the specimen. DESIGN: We have applied the new method to 59 invasive carcinomas and 10 noninvasive carcinomas of the breast, which were judged to be negative for residual tumor by conventional inked margin on the section cut through the center of the tumor. RESULTS: The new method detected 13(22.0%) and 3(30.0%) cases with positive margins in 59 invasive carcinomas and 10 noninvasive carcinomas of the breast, respectively. Nine of 13(69.2%) positive margins in invasive carcinomas were due to the intraductal components of the carcinomas. CONCLUSION: The polygon method is superior to the conventional inked margin method in sensitivity. Furthermore, it covered all the peripheral margins and pinpointed the positive sites.