We appreciate the comments and the citations that Drs. Diaz and Gilcrease have provided.1, 2 We believe that although these articles address similar issues, they differ with regard to fundamental methodology. In our study,3 we analyzed the predictive value of dye gradients within the sentinel lymph node (SLN).
The studies by Cserni and Diaz et al identified and marked the location of a blue–stained lymphatic, assuming that this was the afferent channel. Our trial included a single case in which the SLN was identified in this manner and no lymph node staining was present. The study by Diaz et al also noted the correlation between radioactivity and metastasis location. The identification of lymph node metastases in the portion of the SLN with the highest radioactive counts potentially has the greatest concordance with our work, but because blue dye gradients and radioactivity gradients were not directly compared, we cannot be certain of the superiority of either method.
It has been our experience that the gradient staining of the lymph node is quite easy to see and readily visible at the time of lymph node removal, being anecdotally easier to identify than dissection of the afferent lymphatic, which is not always readily visible. In the article by Cserni, Figure 1, noting multiple SLN drainage patterns, highlights potential problems that might be encountered with this latter method. In small lymph nodes with high radioactive counts, distinguishing which half of the lymph node is hottest also has the potential to be problematic. However, admittedly, our trial did not actively attempt to use these methods or compare them with use of the gradient, and thus it would be unfair to state that either method is superior.
We believe that these 3 studies have each contributed important, although somewhat different, data and agree that all of these works confirm the finding that lymph node orientation, based on intraoperative findings, has the potential to assist in metastasis localization.