Pathological evaluation of sentinel lymph nodes for breast cancer

Recently, sentinel lymph node (SLN) biopsy has been employed to avoid unnecessary lymph node dissection, because SLN negativity for carcinoma metastases may imply an extremely low possibility of non-SLN involvement. Pathological evaluation is essential, but standardized procedures have not yet been determined. Intraoperative consultation, either by frozen section (multiple slices are desirable) or touch imprint cytology, are usually very useful. Their accuracy, however, is variable and depends on the procedures used, but specificity is characteristically 100%, and the missed metastatic focus is always quite minute. After fixation, multiple sections, immunohistochemistry, and their combination will be able to detect small metastatic foci more frequently. The clinical significance of small or submicro- or occult metastases have not yet been clarified, and further investigations are needed. If the SLN is positive for carcinoma metastases, both the procedure for detection and the size of the metastatic focus should be clarified on the pathological reports.