Lymphatic mapping of the skin and breast: locating the sentinel node

Lymphoscintigraphy has been used for many years to study the physiology of the lymphatic drainage of the skin. Following the intradermal injection of 99mTc antimony sulphide colloid images can be obtained using a gamma camera which display the pattern of lymphatic drainage from the injection site. When we first started performing the lymphatic mapping studies for patients of the Sydney Melanoma Unit we were using the study to clarify flow patterns in patients who had melanomas in skin sites which were considered on clinical grounds to have ambiguous lymphatic drainage. These were sites close to the midline of the trunk where drainage could occur to either axilla or sites close to a line drawn around the waist at the level of the umbilicus when drainage might occur to the axilla or groin. Sites on the head and neck were also included as drainage could occur to several different node fields. These clinical judgements were made based on the teachings of Sappey, a French physicians who had produced an elaborate atlas of the lymphatic drainage of the skin late in the 19th century. The imaging in each patient involved standard protocols which has been determined many years previously. In appropriate patients when lymphoscintigraphy had designed the pattern of lymphatic drainage an elective dissection of the node field was performed as part of the treatment of the patients melanoma. Our practice changed dramatically following the description of the sentinel node concept by Morton and colleagues