Histologic localization of sentinel lymph node metastases in breast cancer.

Data from a recent study support the hypothesis that axillary lymph node metastases frequently localize near the inflow junction of the afferent lymphatic vessel. Our goal was to evaluate the microscopic location of axillary sentinel lymph node metastases in a prospective study of breast cancer patients. A total of 305 axillary sentinel lymph nodes from 213 breast cancer patients undergoing surgery at our institution were evaluated. Preoperative lymphoscintigraphy using technetium-labeled sulfur colloid and intraoperative isosulfan blue dye injection were used for identifying the sentinel lymph node. Intraoperatively, the surgeon placed a suture either at the point of entry of isosulfan blue dye or at the area with the highest radioactive counts, and this area was inked at the grossing bench before processing. Metastases were identified in 55 of the 305 lymph nodes examined. Thirty-four nodes contained metastases in both the inked half and the opposite half. Metastatic tumor was identified in the inked half alone in 18 lymph nodes. Only three nodes contained metastatic tumor in the opposite half with no tumor in the inked half (p <0.001). Similar results were found when nodes tagged at the point of blue dye entry and nodes tagged at the area with the highest radioactive counts were analyzed separately. Our findings suggest that metastatic tumor has a higher probability of being present in the region of the inflow junction of the afferent lymphatic vessel. This information may be useful in determining the optimal method for evaluating axillary sentinel lymph node specimens from breast cancer patients.