Axillary staging of breast cancer and the sentinel node.

Pathological aspects of axillary nodal staging of breast cancer and in particular sentinel lymph node (SLN) biopsy are reviewed. SLN biopsy seems an almost ideal staging procedure because it has both high accuracy and a low false negative rate. It may also allow a cost effective use of more sensitive methods of metastasis detection. However, the biological relevance of metastases detected only by modern tools remains to be elucidated. This review focuses on standard axillary staging and the histopathological investigation of SLNs, with emphasis on the intraoperative setting. Future trends including ancillary studies, quality control issues, prediction of non-SLN involvement, and suggestions concerning the minimum requirements for the histology of axillary SLNs are also discussed.