Sentinel lymph node biopsy (SLNB) in breast cancer is considered in order to spare node-negative patients from axillary lymph node dissection. To assess the clinical significance of lymphoscintigraphic mapping in SLNB, we analyzed the lymphatic drain to the sentinel lymph nodes (SLNs) in terms of the pattern and direction of the hot spot. Twenty-three breast cancer patients were enrolled for SLNB. Before surgery, lymphoscintigraphic mapping of SLN was performed using Tc-99m human serum albumin (HSA) and tin colloids, and the hot spot was marked. The Tc-99m HSA and tin colloids were subcutaneously injected above the tumor and peritumor sites, respectively, and lymphoscintigraphic scanning was monitored every 5 to 10 min, for up to 2 h after injection. The SLN was identified using a combination of a blue dye, indigocalmine, and a gamma probe during surgery. The hot spot pattern and direction of the lymphatic drains were evaluated in 21 of 23 cases. Two cases did not have a hot spot. Single, double, and multiple hot spots were observed in 12 cases (52.1%), 8 cases (34.7%), and 1 case (4.3%), respectively. The positions of the hot spots were: axillary (n=17, 80.9%), axillary and sternal (n=3, 14.2%), and phrenic (n=1, 4.7%). The sensitivity and specificity rates in SLNB were 66.6% and 100%, respectively, and the overall predictive rate was 85.7%. Lymphoscintigraphy produced false negatives in three cases (33.3%), including one on the phrenic side. Lymphoscintigraphic mapping with Tc-99m HSA and tin colloids is useful for determining the SLN, and avoiding a false negative. The pattern and direction of the lymphatic drain to the SLN in scintigraphy need to be considered for the elimination of axillary lymph node dissection in node-negative patients with breast cancer.

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