What is a Sentinal Lymph Node Biopsy? 
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   It is often straightforward enough to figure out what lymph node group a melanoma might travel to. Melano­mas of the leg colonize the nodes in the crease of the groin (inguinal nodes), and arm melanomas wind up in the arm­pit (axillary nodes). In other areas, the back for example, the melanoma cells' destination isn't so obvious. A melanoma of the skin over the right shoulder blade might wind up in the left armpit or the right groin. To find the general destination of such melanomas, physicians have started using a tech­nique called lymphoscintigraphy.  This diagnostic technique involves injecting a small amount of radioactive material around the site of a primary melanoma and then scanning different areas--the armpits and groin, for example--to see which one or ones "light up.” The technique is called sentinel lymph node biopsy or (SNLB)and has been designed to determine whether the lymph node that would potentially receive colonies of cells from the primary melanoma has actually done so. The sen­tinel node is identified by injecting a radioactive solution and/or a blue-colored dye into the spot where the primary melanoma is (or was). . After the injection of dye, waiting half hour or so for the dye to travel through the lymph vessels to the node, the surgeonthen reexcises the site of the melanoma. If there is a hot or blue node, it is removed for a pathology examination. If after a few days the node is found not to contain melanoma, then the adjacent nodes are very unlikely to be involved and no fur­ther surgery is necessary. If the sentinel node does reveal melanoma, however, the adjacent nodes are usually removed in what is called a complete node dissection, because there are bound to be some other nodes that are involved as well.
What Are the Pros and Cons of Sentinel Node Biopsy?