Whole-mount pathology of breast lumpectomy specimens improves detection of tumour margins and focality.

Abstract

Technical limitations in conventional pathological evaluation of breast lumpectomy specimens may reduce diagnostic accuracy in the assessment of margin and focality. A novel technique based on whole-mount serial sections enhances sampling while preserving specimen conformation and orientation. The aim of this study was to investigate assessment of focality and margin status by the use of whole-mount serial sections versus simulated conventional sections in lumpectomies. Two pathologists interpreted whole-mount serial sections and simulated conventional sections for 58 lumpectomy specimens by reporting the closest margin and focality. Measurements were compared by the use of McNemar's chi-squared test. Statistically significant differences were observed in the assignment of both margin positivity (P = 0.014) and multifocality (P = 0.021). A positive margin or multifocal disease was identified by the use of whole-mount serial sections but missed in the simulated conventional assessment in 10.3% and 17.2% of all cases, respectively. There was no case in which a positive margin was detected only in the simulated conventional assessment. The whole-mount technique is more sensitive than conventional assessment for identifying a positive margin or multifocal disease in breast lumpectomy specimens. Undersampling in conventional sections was implicated in almost all cases of discordance. The majority of positive margins or secondary foci identified only in whole-mount serial sections concerned in-situ disease.