Redefining cutaneous lymphatic flow: the necessity of preoperative lymphoscintigraphy in the management of malignant melanoma.

Objective: The purpose of this study is to emphasize the instrumental role of preoperative lymphoscintigraphy in the surgical treatment of patients with malignant melanoma.

Summary background data: The efficacy of lymphoscintigraphy is reflected in its ability to reveal cutaneous lymphatic drainage to regional nodal basins that are at risk for melanoma metastases but not necessarily discernable to be at risk through standard historical anatomical guidelines or clinical experience. This preoperative lymphatic mapping technique has contributed greatly to the accuracy and efficiency of staging procedures including sentinel node biopsy and elective lymph node dissection.

Patients and methods: After informed consent, a selected series of four patients with primary melanomas located in watershed areas of the body (left neck, right mid-abdomen, right scapula, left back) and two patients with extremity melanomas (right distal forearm and left ankle) underwent pre-operative lymphoscintigraphy to identify all basins for metastases.

Results: In all of the cases, lymphatic drainage occurred in an unusual and unexpected basin that could not have been predicted clinically and in three of the cases the resected basins contained positive sentinel nodes. If not for the preoperative lymphoscintigraphy, these nodal basins would not have been resected and metastatic disease would have been left behind. In addition, the staging of the melanoma patient would have been inaccurate.

Conclusion: If the sentinel node biopsy of elective lymph node dissection (ELND) were based on clinical predictions only, nodes equally at risk for metastatic disease would not have been resected and in some cases, nodal basins not at risk for metastases would have been resected unnecessarily. Without lymphoscintigraphy, the validity and efficacy of the ELND or the sentinel node biopsy for nodal staging is greatly compromised. These six case studies illustrate the difficulty of predicating lymphatic drainage from primary sites located on the head and neck, truck and even the extremities and demonstrate the indispensability of preoperative lymphoscintigraphy in the management of malignant melanoma.