How Much is Enough? Pathologic Evaluation of Sentinel Lymph Nodes

It is well accepted that detailed analysis of sentinel lymph nodes (SLNs) may upstage breast cancer, but generally involves the identification of low-volume metastases (including isolated tumor cells and clusters). Although several guidelines recommend therapeutic interventions for micrometastases, there is also evidence supporting therapeutic interventions only for macrometastases. There is also evidence in support of means of regional disease control other than axillary lymph node dissection (ALND). The pathologic evaluation of SLNs should consider the clinical setting. Intraoperative assessment is indicated only if ALND is an immediate interventional option for SLN positivity. Generally, hematoxylin and eosin-stained sections taken at 2-mm step intervals are sufficient to disclose macrometastases, but if micrometastases are also considered in further treatment planning, smaller intervals and immunohistochemistry as well as quantitative molecular methods may also be considered.