Optimal histopathologic examination of the sentinel lymph node for breast carcinoma staging

Sentinel lymph node dissection is a minimally invasive surgical technique f or staging of breast carcinoma. The optimal pathologic examination of the s entinel node (SN) has not yet been determined. Our standard protocol for ev aluation of the SN in patients with breast cancer included frozen section a t one level, plus paraffin sections at two levels, separated by 40 mu m, an d stained with hematoxylin and eosin and cytokeratin immunohistochemistry ( IHC) at each paraffin section level. In the current study, we evaluated the use of step sections and cytokeratin IHC in 60 SNs (42 consecutive patient s) that were tumor-negative on frozen section and hematoxylin and eosin sta ining at permanent section levels 1 and 2. The SN were reexamined with cyto keratin MC at eight additional levels (levels 3-10) of the paraffin block, each separated by 40 mu m. Previous IHC sections from levels 1 and 2 had sh own micrometastases in nine SNs (eight patients) and no tumor cells in the remaining 51 SNs (34 patients). Of the 51 previously negative SNs, only two (4%) SNs from one (3%) patient had metastatic carcinoma cells in levels 3- 10. Thus, the additional step sections with cytokeratin IHC did not signifi cantly increase the number of patients with tumor-positive SNs, We currentl y recommend that the SN be examined with cytokeratin MC at two levels of th e paraffin block. This should optimize sentinel lymph node dissection as a staging technique and minimize the labor and financial burden associated wi th multiple step sections and IHC stains.