6. Intraoperative identification of the sentinel lymph node

After we localized the sentinel lymph nodes with scintigraphy, we performed an elective selective dissection. After raising the subplatysmal skin flap, we injected the methylene blue dye to the same area where scintigraphy was performed before.

For the methylene blue dye, we used a Patent Blue V dye (Laboratorie Guerbet, Aulanay-Sous-Bois, France). The amount injected depended on the size of the tumor (from 0.5 to 2 ml) since the entire area of the tumor had to be filled. We observed the spreading of the dye and identified the sentinel lymph node as the one which colored blue. With the use of gamma-ray detector, we confirmed the accumulation of the radioisotope in the lymph node.

If the accumulation was 3-times larger than that of its surroundings, we considered it as a warm node, and therefore as our sentinel lymph node. Most of the sentinel lymph nodes turned blue and accumulated the radioisotope. However, there were some lymph nodes which only turned blue or only accumulated the radiocolloid, but not both. We treated these as the sentinel ones as well. We removed all the nodes that were assumed as the sentinel ones from the dissected material and sent them separately to a histopathological examination with the serial slicing. The rest of the lymph nodes were examined with the classic histopathological methods.
