Gamma probe-guided sentinel node biopsy to select patients with melanoma for lymphadenectomy

A novel approach is described by which to identify the sentinel lymph node in patients with stage I melanoma. The technique involves a combination of intradermal patent blue V injection and gamma probe-assisted surgery. Eleven patients with previously resected cutaneous melanoma, clinical stage I (Breslow thickness 1.35-3.20 mm), underwent sentinel node biopsy. Before surgery lymphoscintigraphy was performed to evaluate the pathways of lymphatic drainage from the site of the previously resected melanoma. A handheld gamma probe was used to localize the sentinel node and to define the exact site of incision. At the same time, patent blue V (0.1-0.2 ml) was injected intracutaneously on either side of the scar to visualize the afferent lymphatic ducts and lymph nodes. By combining the use of the gamma probe and vital dye staining, the sentinel node could easily be localized and identified in all 11 patients. After removal of the sentinel node(s) no residual radioactivity could be traced. In four patients with micrometastases in the sentinel node standard lymph node dissection was performed, including excision of the biopsy site; in only one lymphadenectomy specimen were micrometastases found in two other lymph nodes.