The histopathologic examination of axillary sentinel lymph nodes in breast carcinoma patients

The axillary sentinel lymph node biopsy (SLNB) has gained increasing popularity as a novel surgical approach for staging patients with breast carcinoma and for guiding the choice of adjuvant therapy with minimal morbidity. Patients with negative SLNB represent a subset of breast carcinoma patients with definitely better prognosis, because their pN0 status is based on a very thorough examination of the sentinel lymph nodes (SLNs), with a very low risk of missing even small micrometastatic deposits, as compared with routine examination of the 20 or 30 lymph nodes obtained by the traditional axillary clearing. The histopathologic examination of the SLNs may be performed after fixation and embedding in paraffin, or intraoperatively on frozen sections. Whatever is the preferred tracing technique and surgical procedure, the histopathologic examination of each SLN must be particularly accurate, to avoid a false-negative diagnosis. Unfortunately, because of the lack of standardised guidelines or protocols for SLN examination, different institutions still adopt their own working protocols, which differ substantially in the number of sections cut and examined, in the cutting intervals (ranging from 50 to more than 250 pm), and in the more or less extensive use of immunohistochemical assays for the detection of micrometastatic disease. Herein, a very stringent protocol for the examination of the axillary SLN is reported, which is applied either to frozen SLN for the intraoperative diagnosis, and to fixed and embedded SLN as well.