Axillary sentinel lymph nodes in breast cancer: a single lymphatic pathway drains the entire mammary gland.

AIM: To report the pattern of lymphatic mapping following intrasubdermal injections of radiocolloid and of blue dye in different sites of the breast. METHODS: Prior to surgery 137 breast cancer patients underwent intrasubdermal injection of 30-50 MBq 99mTc-colloidal albumin over the tumour site (ISI group). Ten minutes before surgery, 2 ml patent blue was injected in the subareolar area (SAI group) in 117/137 patients, while 20 patients received intrasubdermal blue-dye in the quadrant opposite the tumour site (OQI group). The different injection routes were considered concordant when the hottest sLN was also blue. RESULTS: In 134/137 patients radiocolloid drained to one or more axillary nodes, while blue nodes were found in 98/117 SAI patients and in 17/20 OQI patients. Multiple hot nodes were found in 63/134 cases and multiple blue nodes in 35/115. In patients in whom both tracers reached the axilla, the hottest node was also blue in 108/115 cases (93/98 SAI and 15/17 OQI patients). In the seven discordant cases, the hottest node was not blue, but in two cases the blue node was also radioactive. CONCLUSIONS: Superficial lymphatic drainage from the breast most frequently merges to a single axillary lymph node, irrespective of the site of tracer injection. In a few cases different injection sites identify different, often closely interconnected sLNs.